Doctors' Answers to "Frequently Asked Questions" - Synthroid

These comments are made for the purpose of discussion and should NOT be used as recommendations for or against therapies or other treatments. An individual patient is always advised to consult their own physician.

Synthroid and weight gain [posted 1/12/99]
Question: My girlfriend has been taking synthroid ever since her thyroid was (95%) removed. She is constantly tired and has been putting on weight despite working out and dieting. This seemed to be a similar concern of many users of synthroid on the FAQ web page, but not one doctor's answers gave any suggestion as to what a person who is putting on weight should do. We were very disappointed that even though many people had her same concern, the issue of weight gain was basically skipped over on the FAQ page. We think it would be better if the doctor specifically answered what concerns the patients had -- why do they gain weight and can't take it off? A few of the comments suggested that once the levels were stabilized, the weight gain would stop after the patient had reached their "normal" weight level. Why is the doctor assuming that the patients were underweight to begin with? My girlfriend desperately wants to lose weight -- she is not at her "normal" weight level and continues to add 2 pounds per month! If you know of any suggestions for someone on synthroid, who has stable thyroid level, can do to lose weight, I would greatly appreciate it.

Answer: Taking thyroid replacement has little to do with weight gain or loss. I know this is counterintuitive, but it is medically the way it is. If taking excessive thyroid would allow weight loss, we wouldn't need drugs like phen-fen, etc. Mohammed Ali tried this in training camp in the 70s and only got tired for his effort. It is true that if your thyroid is over/under active it will affect your weight, but it's not true that replacement medications will have this effect. Weight gain/loss while taking synthroid is no different from someone who is not taking the medication.

Synthroid [posted 1/12/99]
Question: My Grandmother has been on Synthroid for several years and she has just informed me that her physician recently increased her dosage. She does not like to talk about her medical conditions much, but I know she is taking this as a result of cancer treatment in her past. And, even though she won't talk much about her conditions, I do know that she is in very good health for someone that is 72. My concern is this: my grandma is lucky if she can sleep six hours each night (she usually wakes up on the hour if she can fall asleep) and she has problems with her nerves (sometimes she will be shaking her head back-and forth even when she is just watching TV). Her nerve problems may be from something else, but I am wondering how safe it is for her to be receiving additional amounts of Synthroid?

Answer: Well, you'd need to know her TSH level. When this is in the normal range, she is on the correct dosage. When low too much, when high too little (opposite of common sense). Check with her doctor.

Synthroid [posted 1/8/99]
Question: It is my impression that the synthroid may be affecting my hip joint, which is very stiff whenever I change positions. These symptoms of my joint stiffness and aching started and have progressed since Jan 1998. Is it true that I can't stop taking the synthroid now, to see if the joint stiffness goes away? I don't feel many changes since taking the synthroid, perhaps looser bowels and this joint aching, especially in my right hip area. Can synthroid affect bones as a side affect? I know people are different and I would like to see if stopping the synthroid would help. How can I safely do this?

Answer: Excessive thyroid replacement will cause osteoporosis over time. However, I suspect that you are experiencing an increase in osteoarthritis, a common complaint as thyroid is replaced for some reason.

Synthroid [posted 1/7/99]
Question: Can you ever stop taking drugs for hypoactive thyroid disease? I don't like taking drugs if I don't have to. I am 54 years old and also take the drug Estrace. Also will vitamins affect the drugs I am taking?

Answer: Well, it depends on the amount and type of thyroid disease. You can check it by stopping for a week or two and checking a TSH. If it is high you'll probably need it forever. If it is low, maybe not.

Synthroid Questions [posted 12/02/98]
Question: I have been taking synthroid for four years now. Originally, I had hyperthyroid-ism. After radioactive iodine treatment, I now have hypothyroidism. I was eating constantly and lost fifteen pounds within two weeks. I had, before this diagnosis, maintained a weight around 105 lbs. It seemed having an overactive thyroid caused weight loss (bringing me to 90 lbs.). But soon after treatment,I astound- ingly gained thirty pounds! I don't understand when people ask about whether synthroid can help in losing weight, that they are told it can not. I do know that when I am on an increased level, I do have significant weight loss. No matter how much I exercise, or how well I eat, the only thing that helps is an increased level. But I read otherwise in the Q & A site. Am I different? Of course I can't keep an increased level for obvious reasons, but what else can I do to lose weight? What other drugs can be safely taken with synthroid (my level is .175) to help in weight loss? I weigh 125 lbs. and am 5'0". I just want to have some sort of normalcy with this drug. 

Answer:  Well, you are obviously different than most. We don't have very good alternatives for weight loss. Unfortunately, the Phen-Fen regimen is not available, since it did work. Meridia is available;but, I get little success(30%) and it takes a while to work(at 70-80$ month). The only major risk of overreplacement is bone loss(osteoporosis). Get a bone density to see where you are and check it occasionally and increase your dosage slightly watching your TSH closely.

Synthroid Dosage [posted 12/02/98]
Question: I lift weights about 5 times a week and do a lot of cardio exercise also to stay in top health. With this increase in my metabolism, will I need a higher dosage of Synthroid.

Answer: Not usually.

Can Synthroid  Cause Menstrual Irregularities [posted 12/02/98]
Question: I just want to know that I have been on synthyroid for almost 2 months and I am late on getting my period. Is this a side affect of the drug?

Answer: Not if your replacement is complete. At first, it takes a while to get the correct dosage. Ensure that you are not over/under replaced both can cause menstrual irregularities.

Synthroid vs. Generic Synthroid [posted 12/02/98]
Question:  My Dr. just put me on Synthroid because my thyroid is enlarged. My blood work was in normal ranges and my sonogram showed no significant changes. He told me I have a goiter and he wants to start me on  meds. due to fact that it will shut off my thyroid and perhaps cause it to shrink. Is he correct in doing this? What changes can I expect to see? He also told me to go ONLY with the Brand Name not the generic. What about that? 

Answer: This is a common treatment to avoid the gradual enlargement of the thyroid to produce a goiter. This is cosmetically a problem for most people to see a large orange in their lower neck. You can just watch it and start it later, but at some risk that it will not shrink from an enlarged size. It will avoid further enlargement and may cause shrinkage. As to the brand name, I don't think that is a big deal. I would not switch companies frequently, because it can vary from batch to batch. But, one companies product usually doesn't vary much. However, this is one area that brand name is pretty cheap compared to generic.

Synthroid & Weight Gain [posted 11/24/98]
Question:  Please help me answer a question that has been bothering me so much that it keeps me awake at night. I am a 29 year old (obese) female who was diagnosed as having hypothyriodism in April. I am currently taking .075 of synthroid daily. My doctor says that this drug should not cause weight gain, but despite my efforts, such as a healthy diet and working out 5-6 days per week for 2-3 hours each day (including cardio and weight training) I have not seen the numbers on the scale decrease. I was told by another Dr. that the weight should come off due to the drug - I am SO confused and depressed about this. Also, I am being evaluated for a possible bi-polar disorder.

Answer:  Well, it violates common sense, but, hypo or hyperthyroid conditions usually cause weight loss, not gain. So, I wouldn't expect to see much change in your weight with thyroid replacement. If anything, you'll probably gain some. I understand it is counter intuitive;but, check any medical text. 

Questions About Synthroid [posted 11/13/98]
Question: I am a 24 year old female who has been taking Synthroid for approx. 2 years now since they have found that I have hypothyroidism. It just recently (6 months ago) leveled out at .112mg to the point where I am not having to have it checked every 3 months. I have also been taking Alesse-28(birth control pills) for approx. 1 year. I have taken others for the past 4 years. I occasionally take Acidophillus since I have problems with yeast infections. My first question is: Can any of these drugs counteract the other? My second question is: Can any one of these drugs deplete your sex drive? My doctor recently told me that birth control pills can lower certain levels of hormones, therefore I should try taking vitamin E and B6. Is this true? My third question is: Are there any "natural" substances such as vitamins or minerals that can aid in the process of eliminating thyroid problems? I have heard some herb specialists saying that sometimes these can help. My fourth question is: During the 2 years of trying to get my thyroid leveled out, I have gained about 25 lbs. Is there any special diet or anything that can help take this weight off? I know that any type of weight loss regimen states on the back that if you have thyroid problems that you shouldn't take the pills. Is there any type of suggestions that you can give as far as weight loss?


  1. No problem.
  2. Birth control pills can and vitamins will have zero effect. Changing the percentage and type of estrogen may, but not the vitamins. I'm assuming your thyroid is normal and your prolactin levels are ok, this should be checked if it hasn't been.
  3. Herbalists think they can cure anything. I haven't seen anything that works.
  4. No the usual problem. Most patients gain weight as the thyroid is replaced;but, it could be the birth control pills. I wouldn't worry about the diet, you should be able to take most with the thyroid replacement without problem.

Reactions to Synthroid [posted 11/13/98]
Question: I've begun taking synthroid and I'm on 1 mg. I'm getting heart palpitations and racing pulse. However, when I eat my heart rate goes all the way up and I feel like my body is shaking. This occurs especially when I eat sweets. I've taken every test. I have no problem with sugar, in fact, my sugar levels are extremely low, and much better than average. Whenever I seem to take the synthroid, or any thyroid medication, I get rapid heart rate, what can I do to prevent this. I'm hypothyroid and I must take the medication. What can be done?

Answer: Ensure your TSH is in the right range and you are not receiving too much.

Concerns About Stopping Synthroid [posted 11/13/98]
Question: I've been taking synthroid for about nine months and I have been very tired and generally feeling bad since I started. I would like to stop and see if this is the problem. I feel it has to be I felt ok until I started and I have been messed up ever since. Is it harmful to stop? I feel that bad and I just want to feel normal again. My symptoms are very tired, low fever, heck I quit smoking I feel so bad of course that's good. But I know it's the medicine. I'm going to stop taking I would like to know if I will have any problems?

Answer: Probably.

Synthroid Questions [posted 11/11/98]
Question: I have a question, but, first some small medications history. My wife has just been diagnosed with hypothyroid. The Dr. put her on .1mg of synthroid per day. She currently takes other medications (for two years now, unrelated problems):

Previously she had been taking Centrum to help give her more energy. As you might have guessed, the Centrum did not help. My question is two fold. 1) Are there any problems in conjunction with these other medications? 2) Should she stop taking the Centrum vitamins, due to the Iron issues with synthroid?

Answer; Don't take the vitamins with the synthroid is all. I suspect a lot of her constipation is the iron. Unless she is documented with iron deficiency a waste of time and causing problems.

Synthroid [posted 11/10/98]
Question: I have been taking synthroid for about six months now. My endo has been trying to find the right level for me during this time. Most recently, the last two weeks, he up my dosage from .075 to .1MG. because my blood test indicated I was low. While I was taking .075mg I took the medication religiously and felt awful. I was tired, crabby, depressed and anxious. Often I had headaches and had difficulty concentrating and remembering things. I still fell the same since he up the dosage. I tried not taking the Synthroid twice. On each of those day I didn't take it, I felt great! Since I just had my levels checked and they indicated I was low I understand why the doctor increased my dosage. Is their any reason the synthroid itself would make me feel so awful? By the way, my hair is also falling out by the handfuls.

Answer: Your hair is falling out because you are hypothyroid. Sometimes replacement can cause temporary fatigue and reaction as the dose is corrected. This will clear as you stay on the medication. If you don't want to be permanently bald stay on the medication.

Synthroid & Perming Your Hair [posted 10/22/98]
Question: I have been taking .1MG of Synthroid for about a year now. I go to the hairdresser for a permanent wave every three months. My hair will not retain the perm anymore. My hairdresser said that it was the thyroid medicine that was causing the problem. Is this possible? If it is, is there anything that I can do to help the perm take? Could I stop taking the Synthroid for a week or two before getting the perm? Then resume taking it after having the perm. I have very thin, straight, limp hair and for my self esteem I do not want to give up having a permanent wave done.

Answer: What is your TSH? If normal, shouldn't be the thyroid medication. If too low, decrease your medication(a low TSH means too much medication, a high TSH means too little).

Migraines and Eye Pain: Any Relation to Synthroid? [posted 10/21/98]
Question: I just came upon your information in regards to the suit in regards to people using synthroid medication. I have been on this for quite some time and that includes the time mentioned in your article but since I had never heard about this lawsuit, do you have any new updated information about this? Thank you

Answer: I'll relay this to the web master, not my part of the system.

Webmaster Comment: Legal issues are not covered by this site, as such this information should be considered as general information and not legal advice. I suggest you visit, or Miningco's Thyroid Disorders as potential sources of information of this type.

Migraines and Eye Pain: Any Relation to Synthroid? [posted 10/16/98]
Question: I am taking the generic for synthroid (levoxyl)0.05. Since I started this medication I have been having severe headaches, but only on the left side of my head (that makes sense, right?). Anyway, can this be caused by the medication or should I look for another reason? PS I do not think it's not my eyes cause I just had my prescription changed.

Answer: Probably not the medication. Depending on the reason for your thyroid disease, some patients will develop infiltration of the ocular muscles(Graves Disease) which can result in head/eye pain in some patients. This should be evaluated.

Synthroid & Chest Pain: Are They Related? [posted 10/9/98]
Question:I have been on Synthroid for a number of years with no problems, but the other night I woke up with something happening in my chest which is hard to describe. Anyway, it was really a pain just a scary "not right" feeling. I kept having this "wave of where is my heart or is is going to beat again" feeling. I couldn't sleep. I have been having this off and on for several days. It's mostly at night I notice it. I have my levels checked regularly but I have been taking Calcium substitute and wonder if that can be causing it. Because I read that somewhere. Also, I have been unable to lose weight where I've never had that problem before. And I have been exercising for several months. When I went last to doctor, he had me retested because my level seemed high, but then, he said the second test was normal. Please give me your thoughts. Also, I read you FAQ on Synthroid and it seems to me lots of people complain on not being able to lose weight, but you say, that has nothing to do with Synthroid. Thanks for your help.

Answer: Nocturnal chest symptoms are usually due to acid, acid reflux or GI symptoms. I'd try some bedtime Zantac, Pepcid etc. Possibly a hiatal hernia aggravated by your weight.

Synthroid & Iron Supplements [posted 10/1/98]
Question: I was diagnosed with Hashimoto's thyroditis a few years ago, but my thyroid levels have remained within normal range with periodic testing. After a thryoid enlargement a few months ago my doctor started me on Synthroid about a month a half ago. But, I have also had a longterm anemia that is not responding to iron supplements taken for the past year. I am now taking Yellow Dock for the anemia (a herbal iron supplement), but will I be able to take type of iron supplement now that I'm taking the Synthroid?

Answer:Don't take the Synthroid and the iron concurrently and you'll probably be ok. I tell my patients who need both to take the Synthroid in the AM and the iron much later in the day.

Synthroid [posted 10/1/98]
Question: What types of food should I avoid after taking Synthroid?

Answer: There are several potential "foods" or drugs which decrease absorption of Synthroid. These are ferrous sulfate(iron tablets or vitamins containing iron),sulrafate(Carafate),aluminun hydroxide (aluminun containing antacids) cholestramine resin(cholesterol lowering agent generally),colestipol (ditto), sodium polystyrene sulfonate, and baby formula containing soybean flour(also some vegatarian diets).

Synthroid Doses [posted 8/13/98]
Question: Why does it take so long to achieve euthyroid status? I was hypothyroid in October, and have been gradually treated with Synthroid (I am also taking 900 Lithium and 1 Rivotril per day), first with 0.175 dose which proved to be intolerable (heart attack like symptoms), then reduced to 0.163, then 0.100, and now I am on 0.112. Why so long? I would appreciate an insight into how the hormone works.

Answer: The hormone works immediately. However, predicting an individual's need is the trick. Most physicians would not start replacement at 0.175 mg due to the exact problem you describe. Most start at smaller doses and work up, but it does take a while to find your exact need. This is the reason for the time delay. Every individual is different although there is a range generally from .05 to .25 in which most individuals fall.

Synthroid [posted 8/5/98]
Question: I have several questions regarding Synthroid. I have been euthyroid since 1987 after I131 treatment for hyperthyroidism. I have been on Synthroid since that time. My levels have always fluctuated. I have to take labs every three months because of constant value changes. I have been on as high as .288 mg. I have read some of the FAQ on your site and am quite interested in asking specific questions. I love sushi and kelp, seaweed is in the sushi. I read there is an absorption problem because of the iron in kelp and the Synthroid. I eat sushi two or three times daily. So, how does this affect me? I am sleeping constantly. I read that overdosing of Synthroid can cause lethargy and fatigue. I don't understand why. Is this true and why? I have been 100 pounds overweight for 9 years. I can't lose weight. With the above fluctuations in labs and my high dose, is it possible that I was taking too much synthroid and therefore I am tired all the time and obese? I have had enormous blood work done, gamma globulin treatments, TAH/BSO, am on estrogen replacement and zoloft. Do any of these factors make a difference in my thyroid picture? I am under the care of an endocrinologist in Hollywood, Florida and he doesn't seem to have any answers. Because of my various symptoms: obesity, fatigue, fluctuations, should I seek another endocrinologist, maybe such as Cleveland Clinic, Florida for further advice?

Answer: The iron won't be a problem, however, the high iodine content in kelp can decrease thyroid functioning. This is not a problem on thyroid replacement, but can be in individuals not taking thyroid replacement. Secondly, these variations are extremely unusual. I suspect the testing is being done incorrectly. Most individuals don't vary more than 0.05 mg per year after achieving a stable base. I would really focus on getting the proper testing and thyroid dosing before getting too focused on any other issues. See another doctor.

Levoxyl and Vitamins [posted 7/23/98]
Question: I am a 49 year old female and I just started taking levoxyl 50mcg (generic for synthroid) due to my recent physical with an elevated blood test results. I also take a lot of vitamins(chelated iron, calcium, mag and zinc, B-100, selenium, vitamin E, chromium Picolinate, b-12, lysine, vitamin C, (I have had a hysterectomy and take Premarin also). I exercise regularly and am trying to lose 10-15 pounds. Is there any problem taking all these vitamins with my other medications, and will my weight get regulated after I have been on levoxyl? I have suffered from Insomnia most of my life. I am 5'3, 127 lbs. My doctor gives me amitriptyline 10 mg, one tab at night to help promote sleep. Am I taking way to much stuff and should I eliminate some of these vitamins? I used to get a lot of cold sores inside my mouth and some of these vitamins have eliminated that problem.

Answer: There are several things to avoid taking concurrently with synthroid. Iron supplements (about the only "vitamin"), infant soy formula, antacids, sulcrafate (Carafate). Absorption is a little faster on an empty stomach, but clinically doesn't seem to have much of an effect with or without food. No obvious interaction with any antidepressant. So, cut out the iron supplements (you probably don't need them after a hysterectomy anyway).

Synthroid Side Effects [posted 7/16/98]
Question: I have been taking synthyroid since 1990 for a hypothyroid condition. Recently I had my prescription refilled and opted for a different generic brand of synthyroid. I began to experience tinnitus. It seems that I saw something that stated that tinnitus can be a side effect of synthyroid. Is this true?

Answer: I have never seen tinnitus as a side effect of levo-thyroxine and the generics are pretty close in side effects.

Synthroid & Estrogen
Question: I am a 47 year old female who had a hysterectomy at 28 due to cervical cancer (retained ovaries). 3 years ago I was treated for Graves Disease including radioactive iodine treatment and replacement hormone treatment. Currently taking .125 Synthroid daily. A recent FSH test indicated very minimal Estrogen levels. My doctor is recommending low dosage estrogen replacement and a decreased dosage of Synthroid to .112 to combat current menopausal symptoms of hot flashes, headaches, fatigue, dizziness, etc. I am a heavy smoker, obese (although active), have blood pressure of 110/72, fibrocystic disease and a maternal history of breast cancer. What are the contraindications, if any, of beginning hormone replacement therapy given my background?,

Answer: The overwhelming risk for women of premature death is cardiovascular. The exception to this are women with distinct histories of familial cancer-- especially breast. If you have a first degree relative(mother, sister ) with breast cancer the risk of estrogen related breast cancer seems to outweigh the risk of cardiac disease. If you have numerous second degree relatives(aunts, cousins) who have early cancer(before 50 or so) the risk of estrogen may outweigh its benefits. Otherwise, betting the odds take estrogen. Estrogen is about the only drug which reduces cardiovascular risk. After women stop estrogen, their cardiovascular risk is equal to men. Also, estrogen will decrease the risk of osteoporosis. In general, your longevity and quality of life will be lots better with estrogen. The only proven risk is uterine cancer. Breast cancer is still not absolutely proven, although most physicians believe that there is a link-- particularly in familial breast cancers.

Synthroid and Menopause
Question: My mom's doctor said that since she is taking Synthroid because of the removal of part of her thyroid due to lymphoma, she must use hormone therapy replacement upon menopause. I was wondering if there is some supportive literature we could find on this.

Answer: There is no obvious connection between taking estrogen and thyroid replacement. Many women take thyroid replacement without estrogen replacement. I am generally in favor of estrogen depending on the patients individual risk profile. However, there is no connection here that I am aware of.

Synthroid and weight gain
Question: I would like to know is it possible that a certain type of thyroid replacement may not work on certain individuals. I have been on Synthroid for 17 years and have constantly gained weight. Since my thyroid went I have gained 60 lbs. in 17 years. I have said since day one that even though my blood levels are all in normal range something is out of whack. I diet constantly and exercise 5 days of the week, and I still gain. My husband has even talked to these doctors about my dieting and exercising. I think that maybe switching brands to see if anything would change is a good idea, but I can't get a Dr. to try since my levels are in normal range. I have also started taking some Kelp.

Answer: Strangely enough thyroid replacement pills rarely effect one’s weight. That is increasing the dose won't cause weight loss as one would logically expect. If your TSH is not too low, you might try increasing the pill slightly, but I doubt you'll see any change. Changing the manufacturer won't help. Check the TSH and keep it between 1-2. Kelp will cause some thyroid problems due to the high level of iodine in it. Let your doctor know that you’re taking this.

Temper vs. medication
Question: I am a 37 year old male that has been a shift worker for thirteen years. Can my 0.075mg synthroid or 20mg Levastol cause any mood swings or short temper? I was diagnosed with hyperthyroidism in 1986 and treated by radioactive iodine treatment. I have a five year old son, and my wife is concerned as well as myself about my swings in temperament. I can be fine one minute and just fly off the handle the next. Most of the time is when I am correcting my son. I feel at times I shout too much. I should be able to control my frustration, but I can't.

Answer: 1. Is your thyroid appropriately dosed? .075 is a small dose for most men. 2. Did you have complete ablation or just enough radiation to "turn down" the thyroid? If not complete ablation, hyperthyroid or hypothyroid will usually occur over the ensuing 4-5 years. 3. Do you have another glandular problem? 10-20% of patients with hyperthyroid will develop diabetes, adrenal insufficiency, B12 deficiency, etc. 4. Why are you taking Levastol? This is a selective beta blocker type drug used only in hyperthyroid states. If you no longer are hyperthyroid, it is usually used in treatment of hypertension. If you don't have hyperthyroidism, this drug makes little sense.

Synthroid and Pregnancy
Question: I take 0.88mgs of Synthroid a day for Hypothyroidism. I was wondering if it is safe to continue this if I were to become pregnant.

Answer: Absolutely.

Question: Two months ago I had a radioactive iodine treatment for my Graves disease. Since that time, I have gained 15 pounds. I will start taking synthroid probably within the next week, based upon the results of my latest blood work. Will taking this medication help me lose the weight I've gained since I've started treatment (nothing else seems to be working including diet and exercise). As a side note, I lost very little weight with the Graves, but since my diagnosis a year ago I've gained 25 pounds total.

Answer: First, you must make sure that you are on adequate replacement(keep the TSH in normal range). However, thyroid replacement will not add or subtract weight. I suspect it was treating your hyperthyroidism and getting your system to normal that is responsible for the weight.

Question: My wife began taking Synthroid two weeks ago after the removal of her thyroid gland. This was done because of nodules on the thyroid and the fact that she had radiation treatment in the early 1960's. We are concerned with the side effects of the synthroid. She was told not to take calcium at the same time as the calcium stops the absorption of the Synthroid. Is this fact correct? Additionally, how long should it take to regulate the Synthroid to the proper levels?

Answer: Side effects of synthroid are usually none unless the drug is not replaced properly. Too high or too low a dose will cause problems. The drug should not be taken with aluminum hydroxide antacids, cholestramine (or equivalent) iron tablets, sucrafate(Carafate), and soy based infant formula. There are several drugs that can change metabolism through changing protein binding changes or direct effects on the thyroid. Refer this one to your MD. Usual doses for women are about 0.1 mg to 0.15mg. Occasional patients post ablative surgery will require to 0.3 mg.

Synthroid and Hair Loss
Question: Can an increase in synthroid dosage (due to hypothyroidism) cause severe hair loss?

Answer: Not usually if it is an appropriate dose. However, hypothyroidism will produce hair loss and it usually occurs after the hair has grown out about 1/4 inch. So, if the thyroid produced better and healthier hair there will be a weak spot from when the thyroid was low. This produces hair loss about a month after the thyroid is replaced. This will continue for about six months and then correct itself.

Question: My doctor is increasing my Synthroid dosage. I am now at level 0.088, and my thyroid level is still low. In the last few days since I've started the new dosage, I have noticed moderate amounts of hair falling out. Is this normal, and how long will it continue? Is it a side effect of synthroid or hypothyroid condition? My thyroid condition started with Graves' disease, and after the radiation cocktail, very quickly I became hypothyroid.

Answer: Hair tends to fall out about 3-4 weeks after the time of medication imbalance. This is because a weak spot in the hair firms with hypo or hyperthyroidism. As the hair grows the weak spot grows out also. When it reaches about 1/4 inch, the hair tends to break causing hair to "fall out". I suspect that the current hair loss is due to a problem about a month ago when your thyroid was really out of balance. Decreasing the length of your hair will help this problem by decreasing the weight so that the weak spot will not fracture. Synthroid will not cause hair problems per se. An inaccurate dose can.

Question: Can Synthroid make weight loss difficult or cause a person to gain weight? My father has no thyroid left and takes 0.2 and .025 mg of Synthroid per day. He's been on a high protein, regular to high fat diet with no carbohydrates, no sugar, no caffeine, and no alcohol. He also works out almost every day (aerobically). He's been eating this way for a month and still can't lose any weight.

Answer: While insufficient thyroid can produce either weight gain or loss depending on the individual replacement does not have an appreciable effect. If it did we would use it in weight loss or gain, but it clinically does not have this effect. Logically it should.

Question: I have been experiencing slight mood swings, loss of hair, and breakouts on my skin and specifically my face. Could this be a possible side effect of Synthroid?

Answer: I doubt that this is the thyroid replacement. Probably, you have an incorrect replacement dosage or are experiencing the residual effects of the time when you had insufficient thyroid since it takes about 3 months to completely reverse the effects of hypothyroidism. I really rarely see patients with any reaction to thyroid replacement since it is replacing a hormone that your body uses every day.

Synthroid absorption
Question: I've heard that soybean flour interferes with Synthroid absorption. Do other soybean derivatives like tofu, products that contain soybean oil, or soybeans themselves interfere with Synthroid absorption? Should I avoid these foods, or can I go ahead and eat them as long as my dosage is monitored and adjusted properly?

Answer: Synthroid(levothyroxine) is a commonly used medication for replacement or suppression of thyroid hormone. Decreased absorption has been documented with ferrous sulfate(iron), aluminum hydroxide(found in antacids), Carafate(sucralfate), infant soybean formula, and bile acid sequestrants. There is no evidence that soybean derivatives in an adult diet make an appreciable effect.

Synthroid dosage change
Question: My doctor just raised my synthroid level from 0.1 to 0.125 mg because my TSH was a 23 with the high limit on the lab test to be no higher than 9. I recently had my gallbladder taken out. Could this have caused my levels to change? Also, I should tell you that I have only been on synthroid one year because I had thyroid cancer, had to have my thyroid removed, and then had to take I123 radiation therapy. What can I expect as "adjustment" effects from a change in dosage?

Answer: Synthroid is given after surgical or radiologic ablation of the thyroid to replace the hormone the thyroid produced. TSH is a pituitary hormone which "turns on" the thyroid. Physicians use this to measure what your body needs. That is, a normal TSH implies that the dose of synthroid is sufficient. A high TSH implies that the dose is too low. This should be checked every 3-4 months until the levels are stable. Doses vary quite a bit from 0.05 to 0.3 mg depending on your size, age, and the degree of damage to your thyroid by the I131.

Question: I just found out that my thyroid has stopped working. My endocronologist immediately put me on synthroid (green) and my symptoms have improved. He said he is very pleased with the numbers of my TSH, etc. My question is: I seem to be having good days and bad days. I get tired very easily (especially with stress at work) and sometimes some of the symptoms reappear. Is this the way it is going to be with this condition, or over time will the symptoms disappear?

Answer: Sometimes it takes a while to regulate the thyroid levels. This is best accomplished by following TSH levels. When they are normal the thyroid that you are taking is right for you. Occasionally, patients with hypothyroidism also develop adrenal insufficiency or B12 deficiency. I would at least raise these as possibilities with your physician.

Question: My sister is pregnant and her Doctor has told her it is OK to continue taking Synthroid. (She was taking it before she got pregnant.) Is this true? She's 29 and otherwise in good health.

Answer: Synthroid(levothyroxine) is a commonly used medication for replacement or suppression of thyroid hormone. Decreased absorption has been documented with ferrous sulfate(iron), aluminum hydroxide(found in antacids) Carafate(sucralfate), infant soybean formula, and bile acid sequestrants. There does not appear to be any contra-indication to taking this drug during pregnancy. Indeed, if there is a deficiency and the drug is not taken harm can come to the fetus.

Question: I have been taking 0.1 mg of synthroid for my thyroid disorder for one year. Prior to that, I was taking 0.15 mg. Blood tests indicated that I needed the lower dosage, but I was consistently tired and seemed to get sick more often. My doctor put me back on 0.15 mg because of my weight gain and fatigue. Will a higher dosage cause problems?

Answer: The negative long term effects of excess thyroid supplementation center on increased osteoporosis. There is no other clear long term problem although research is ongoing. There are several doses available between 0.1 and 0.15 mg. Possibly 0.125 or 0.112 might be the answer.

Question: My wife has been taking synthroid for over a year. I changed jobs and because of that, health care providers. When it came to refill the prescription, they didn't tell my wife that they were switching from synthroid to levothyroxine. She didn't notice the prescription change either. For about a week she was the most irritable, temperamental person I've ever met. One moment she would be fine and then something stupid would happen and she would fly off the handle. One morning she just happened to read the label. Well, she was upset that the health care providers would change her prescription without telling her. She called and said she wanted to be put back on Synthroid. They obliged and within a few days she was back to normal. We concluded that the mood swings and sudden personality changes were due to the changed in medication. Is there supposed to be such a significant difference between Synthroid and Levothyroxine. I am also concluding that levothyroxine is generic.

Answer: Levothyroxine is the generic for Synthroid. Usually there isn't a major difference, but switching manufacturers does usually require that her TSH be checked. Usually, there is no major differences depending on the TSH. However, if she is better on the brand name the cost difference for this drug is fairly small and is about $5 or $6 a month.

Synthroid/Weight Gain
Question: I am 19 years old and have been taking synthroid since I was born because my thyroid is cracked. I used to have moderate body weight and have gained weight suddenly without eating more or changes in exercise. Why is this happening? Should my dosage be changed? I am currently taking 0.125 mg per day.

Answer: Your thyroid should be checked about once a year or with any major metabolic change. I doubt that the thyroid is the cause, but it is easy to check with a blood test.

TSH vs. T4 in Hypothyroidism Diagnosis
Question: I am a healthy 52 year old male. I have taken levothyroxine, primarily in the form of Synthroid since I was 26 years old. Until recently, with the emergence of the new more accurate blood test for TSH, I likely took too much levothyroxine between 1971 and 1995. In 1995 my General Practice Doctor began to lower my dosage, based solely on the test result for TSH. Over a 2 year period he lowered my dosage from 200 mg per day to 112 mg. I did not feel that dosage was the correct dosage. I did not feel that my body was working like it should, but he would not raise my dosage. I am now attending an Endocrinologist specialist. In doing so I have learned that it is not appropriate to use just the TSH value alone to decide proper levothyroxine dosage, but that a doctor should carefully review the biochemistry of the body as the TSH and the other enzymes and chemicals in the body work together. My specialist is using TSH values and T4 values synergistically to determine my correct dosage. Currently it looks like I will stabilize at 137 mg per day. The moral is that using TSH alone may not be sufficient in itself to set a proper dosage of levothyroxine. Any comments on this issue are most welcome.

Answer: One should never treat just a biochemical test. While the TSH is a great part of the equation, the exact dosage necessary to keep you vital will vary greatly.

Question: Is it true that taking synthroid will cause weight gain? If you are taking it to help you loose the weight you gained from being under active wouldn’t you be defeating the purpose if you gain more weight? If this is true, will you eventually lose the weight once your body gets used to being on the medication? I've been on it 5 months, put on 8 pounds after 3 weeks of being on it, and can't seem to lose weight no matter how strict I am with my diet and exercise program.

Answer: Synthroid (levothyroxine) is a commonly used medication for replacement or suppression of thyroid hormone. Decreased absorption has been documented with ferrous sulfate(iron), aluminum hydroxide(found in antacids), Carafate(sucralfate), infant soybean formula, and bile acid sequestrants. Weight gain will occur in some patients as their body is restored to its usual weight. It will not continue as a result of the drug once the usual weight is achieved.

Question: I have been told to take Synthroid either 30 minutes before or one hour after the morning meal. Is this critical?

Answer: Synthroid (levothyroxine) is a commonly used medication for replacement or suppression of thyroid hormone. Decreased absorption has been documented with ferrous sulfate (iron), aluminum hydroxide (found in antacids) Carafate(sucralfate), infant soybean formula, and bile acid sequestrants. Food doesn't seem to make a crucial difference.

Question: I have been taking Synthroid for several years. During both of my pregnancies, my doctor took me off Synthroid. I had preeclampsia with both babies and am curious as to whether or not this action could have attributed to my toxemia. If I remained on the medication during another pregnancy would my chances of preeclampsia be as great?

Answer: You fail to mention why you are taking Synthroid in the first place. If it is to replace thyroid hormone due to hypothyroidism, many side effects would result. If it is to manage a goiter size, few side effects would result.

Question: Could you please include information in relationship to over-exposure to Synthroid and the complications that it can cause.

Answer: Taking excessive synthroid produces many of the symptoms of hyperthyroidism. These symptoms are fatigue, racing pulse, nervousness, irritability, diarrhea, etc. Curiously, taking excess thyroid does not cause weight loss, but weight gain.

Question: I have recently begun taking Synthroid. I take a multi-vitamin with iron and 1000 units of Vitamin E. My doctor's office told me that I can take the vitamins as long as I don't take them at the same time. I take the Synthroid in the morning and the vitamins at night, since they upset my stomach. Also, I take Lithium. When I began having symptoms, my doctor took me off the Lithium. After I went back on the Lithium, my TSH went from 0.03 to 37.7. Can Lithium cause that much of a change? Would it be wiser to go off the Lithium than to take one medication to counteract another?

Answer: Lithium can cause an underactive thyroid. The question is whether the under active thyroid will be eliminated without the lithium and how important is the lithium. Synthroid replacement is pretty simple and benign, merely replacing your own body’s hormone not unlike taking estrogen in women. If the lithium is necessary for a mood disorder there is no other good substitute. You'll probably wind up on the thyroid regardless and you'll have to decide the benefits of the lithium.

Question: I'm a 41 female with a history of weight gain, irregular heartbeat and hysterectomy. I am taking hormone replacement therapy along with 0.1 mg of synthroid. My weight has continued to increase, no matter what diet I choose. I am a vegetarian, eat healthy and stay away from sugar. Can an increase in this drug help to curb my weight?

Answer: Increasing the synthroid will not cause weight loss. If it did we would prescribe it by the bushel. Increasing the synthroid will only cause cardiac irregularity, fatigue and thin bones. I suspect your hormone replacement (estrogen?) is the culprit.

Question: I am a 32-year-old woman taking 200 mg of Synthroid daily. I am obese and thinking about going on the diet drug, Redux. Are there any side effects or drug interaction problems by taking these two drugs together? I am also taking 5 mg of Norvasc daily as well.

Answer: Redux(dexfenfluramine hydrochloride) and phenteramine/fenfluramine are appetite suppressants. They have been used for the past several years to aid in weight reduction after publication in JAMA of an article and subsequent follow-up articles detailing the weight loss potential of this drug with very few side effects. These drugs are indicated for weight loss necessary to correct or improve the treatment of hypertension, diabetes mellitus, and elevated cholesterol, with a body mass index of 27, or no risk factors and a body mass index of 30. Body mass index is arrived at by dividing your weight in pounds by your height in inches. These drugs should not be taken with MAO inhibitors, Imitrex(used for migraines), while pregnant, with anti-depressant drugs of any variety-especially SRI inhibitors, if glaucoma is present, or if under 18. Usual dosage of Redux is 15 mg twice a day. Ionomin's dosage is 15 mg once a day-30 mg if the individual is unresponsive. Pondomin's dosage is 15 mg three times a day. This can be increased to 30 mg three times a day(t.i.d.). These drug regimens do not appear to be addictive currently. The biggest risk appears to be pulmonary hypertension. This is increased with taking these drugs and can lead to death, so it is not taken lightly. This appears to be an unusual but serious side effect. Common side effects for most patients are dry mouth, constipation, diarrhea, and drowsiness.

I have had a lot of success with these drugs. Redux is easier to take, but may not be as effective. Ionomin and Pondimin are a little more effective, but less convenient and slightly more costly. The weight loss tends to return after the medicines are discontinued, but they are usually effective in about 80% of my patients. I have major concerns about pulmonary hypertension and I do not prescribe these drugs until all the risks are laid out and only for high-risk patients. There should be no interaction with Synthroid or Norvasc that I am aware of.

Side effects of Synthroid
Question: I have been diagnosed with thyroiditis. The doctor has started me on a very low dose of synthroid and will adjust it in 30 days. I am currently on day 7 now. The first day caused a profound headache, thereafter, tendency to headache, especially after eating. The medication seems to be making me more hypothyroid rather than less, fatigue, feeling of hypoglycemia, bloating from eating, not digesting my food well, among other things. I have been told by the pharmacist that persons who are allergic to pork, beef, etc., may have an intolerance for synthroid. I am allergic to these substances.

Answer: Quite honestly, your pharmacist is full of baloney(not pork). Synthroid is made synthetically and not derived from either pigs or cows. It is identical to human thyroid hormone-desiccated thyroid is derived from cow thyroids and I guess there could be an allergic problem here and there. I suspect your problems have to do with insufficient thyroid replacement. Often the symptoms of hypo and hyperthyroidism are very similar. Stick with the medications possibly speed up the dose if you are young after checking your levels. Also, occasionally patients have co-existing adrenal insufficiency. The only time I've had trouble with patients starting thyroid is when they have insufficient adrenal hormones and the addition of thyroid hormone magnifies this problem - suggest this to your physician - its medical name is Schmidt's Syndrome.

Question: My wife takes 175 mg of synthroid daily. She is concerned that synthroid may have a negative affect on her heart. Is there any concern with taking synthroid and heart problems? She is 34 and has no other medical concerns.

Answer: Thyroid replacement when done correctly has no effect on the heart. Excess levels can cause irregular heats, rapid pulse, and blood pressure swings. The best way to test a thyroid level is to check the TSH(thyroid stimulating hormone). This is a hormone produced by the body to stimulate the thyroid gland. When the body feels that there is insufficient thyroid hormone, it produces more TSH in the pituitary. So by checking the TSH, one can tell if the pituitary thinks the body has too much, too little, or just right levels. A low level of TSH indicates that too much thyroid is available(the body is trying to turn the thyroid down) a high level of thyroid indicates that there is insufficient level of thyroid(trying to turn the thyroid on). Either too much or too little thyroid will affect the heart. The goal is to give just the correct amount for each individual so that it mimics ones own thyroid gland.

Synthroid vs. Levoxyl (generic)
Question: I am currently taking Synthroid 175mg, and the pharmacist offered to give me Levoxyl 175mg. The pharmacy assured me that they are equivalent and levoxyl costs half as much. Is it truly equivalent?

Answer: Generics are generally equivalent to brand name drugs; however, there are exceptions. One's thyroid dose is optimally achieved by testing the blood levels of a hormone called Thyroid Stimulating Hormone. If this hormone level is normal the level of thyroid replacement is deemed sufficient. Consequently, if one uses generic or brand name thyroid the blood test is the best way to determine efficacy. I have had patients who have required slightly different doses of thyroid replacement on generic versus brand name. However, it is usually clinically equivalent. I would recommend at least yearly testing of thyroid stimulating hormone(TSH) to ensure your levels are optimized. Also, I would be reluctant to switch the companies which manufacture your thyroid excessively.

Synthroid & Fiber
Question: I take synthroid daily. My question concerns a problem with fiber and synthroid combined. I have read health articles stating that individuals who take synthroid daily and eat a high fiber diet had problems with the effectiveness of the synthroid. The article stated that the synthroid was not absorbed by the body of those individuals who ate a lot of fiber foods. I do eat high fiber foods and recently my test results show a extremely high levels (7.4 out of a scale .4 - 2.5), so my doctor is raising my synthroid dosage from .175mg to .188mg. I would like to know if you have any information concerning the fiber-synthroid information I've discussed. Does high fiber have any connection with the low absorption of synthroid? I would like to know.

Answer: Synthroid(levothroxine sodium) is a synthetic thyroid that is identical to that produced by your body. Synthroid is absorbed throughout ones small intestine and the amount that is absorbed varies from 50-80% of the oral dose. Any disease or disorder of the small intestine will potentially alter absorption as will the contents of the small intestine. Known factors which affect absorption are ferrous sulfate, aluminum hydroxide antacids,infant soybean formula, sucrafate(Caratate), and bile acid sequestrants. While fiber may effect the absorption, if the fiber is relatively constant in the diet adjustment by ones physician-as yours is doing-will compensate for this effect. Watching ones fiber intake from day to day is not necessary since the thyroid taken today will have approximately four to five days of biologic effect.

Side Effects
Question:Several years ago I had a total thyroidectomy. The cancer reappeared. My physician then prescribed I-131. He then set my synthroid level at .225mg. This he said was to combat the cancer. At lower doses the cancer reappears. This diagnosis is based on thyroglobulin test. My question is how can I alleviate the side effects (tremors, angina, dizziness, tachycardia, insomnia, violent dreams, depression and anxiety) of the synthroid at the high dose I am taking?

Answer: You have been made medically hyperthyroid to treat your cancer. Consequently, drugs used in treating hyperthyroidism may be effective. Beta blockers are very effective in blocking the tachycardia, tremor and probably the angina. If you are truly having angina with the dose of thyroid I would consult your physician or another specialist? It would be unusual to need to give this much thyroid to block thyroid cancer.

Question:How long can a 31 year old female patient go without Synthroid (1.5 mg dose required) before they have serious side effects?

Answer: Synthroid(levothyroid) is the synthetic version of human thyroid hormone called T4.(There is also a T3.) Synthroid is given for various reasons. Consequently, the reason you take synthroid as well as the time that it is missed both are involved in deciding the length of time for consequences to occur. For example some people take synthroid to suppress a goiter. This is primarily a cosmetic problem to keep the gland from enlarging to unsightly dimensions-also putting pressure on the esophagus occasionally. Stopping synthroid in this situation will result in no appreciable change or side effect. Since the gland is still functioning it begins producing thyroid hormone and no consequences ensue. However, if one is taking synthroid for hormone replacement-as most are- side effects will begin in about five days. After twenty to thirty days one is usually hypothroid again with all the ensuing side effects. These can be many and are very individual. Fatigue, weight loss, anemia, loss of periods, galactorrhea(breast discharge), constipation, cold intolerance, may be seen very early. Later, decreased mental ability, menorrhagia(very heavy periods), dry skin, thin hair,swelling around the eyes and a dull expressionless look to the face will occur.

Synthroid and DHEA
Question:My wife is taking synthroid at the present time. Is there any reason she should not take DHEA also? Thanks.

Answer:DHEA(dihyroepiandosterone) is a drug belonging to a class of drugs called steroids. Taking these should have no appreciable effect on the dose of thyroid medication. However, I would occasionally check her TSH levels to see. DHEA is such a new phenomenon that there is not lots of medical information or research available. However, it is very simple to check the thyroid level to ensure that the level of hormone is not effected by DHEA.

Absorption of Synthroid
Question:I am currently taking Levoxyl .15 mg per day. About six weeks ago I began experiencing hot flashes and constipation. I am 50 years old and my recent FSH level indicated that I am post menopausal although my last menstrual period was 10/26/96. There has also been a recent increase in my TSH and my Levoxyl dose is being reduced by half. Is there any connection between menopause and changes in T4 levels?

Answer: Estrogen affects the binding sites of synthroid(levothyroxine). However, this does not affect the total dosage of thyroid necessary-only that amount bound to receptor proteins. I would ensure that your physician is using TSH for dosing-a much more accurate Estrogen affects the binding sites of synthroid(levothyroxine). However, this does not affect the total dosage of thyroid necessary-only that amount hound to receptor proteins. I would ensure that your physician is using TSH for dosing-a much more accurate indicator that Free T4 or Free T3 in women on estrogen.

Back to Drug InfoNet Home Page.

Back to Medications/Pharmaceuticals main page.

Send your impressions, comments, thoughts, etc. to
1996-99 DRUG INFONET, Inc. All rights reserved.
Last modified January 12, 1999