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Doctors' Answers to "Frequently Asked Questions" - Drug Testing

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.

LSD and Urine Test [posted 1/14/99]
Question: Will LSD show up for a urine sample? I didn't know if there were any stipulations or not. I used it this past weekend and have to take a drug test on the 24th of this month. Will I be okay?

Answer: Depends a lot on the drug test, but is generally picked up by most drug screens and may last several weeks depending on the sensitivity.

Drug testing [posted 1/8/99]
Question: Could the presence of the following drugs influence the outcome of a drug test towards being THC positive? : Percocet, Vicodin, Tylenol 3, sudaphedrin, and methocarbamol.

Answer: Depends on the test. You'll need to get the cross reactivity index from the producing company. Usually not, but very test dependent.

Narcotic testing and cross reactions for positive results [posted 1/8/99]
Question: I was recently given a complete urine drug screen. I was on Lortab and Soma at the time, and the results were positive for benzodiazepines. I was told by a Judge that Soma can cross react, but another Judge thinks I am taking Valium. Could you inform me if this is possible, and possibly send me proof if this is true? I am on Community Control and had gone to court to get it reduced after 20 months drug-free.

Answer: You'll need to get a list of cross-reacting substances from the company who makes the test. They have this information and will tell you the cross reactivity rate with soma.

Drug Testing - Marijuana in the urine [posted 1/6/99]
Question:My son will be taking a physical for the coast guard soon. He has not smoked any pot in over two months and has been working out (weight lifting) and drinking lots of water. The Coast guard official said that he will take a urine test for drugs. Is two months enough time for his system to clear?

Answer: Depends on the test, but usually not.

Hydrocodone & Drug Testing   [posted 12/01/98]
Question:  I have taken hydrocodone (3 tablets in 24 hrs. and the next few days 1 every 8 hrs.),  for pain from a bulging lumbar disk. I will be taking a drug test for a job some time in the next week or two for a possible new job. Will this show in the testing? Thank you for whatever information you can give me.

Answer: Usually will.

Can Zantac Cause a False Positive Test Result  [posted 11/19/98]
Question:  I have been taking Zantac (for GERD) for the past four years. It works great... no problem. Two weeks ago I had to give a urine sample at work. Last week I gave another one. The results came back today for both tests showing amphetamine in my urine. I don't drink, smoke or take ANY drugs except the Zantac and a face cream for roseacea. They made me give another urine sample today. I'm a dead man if it comes back indicating illegal drugs. Can you help me? Is it possible that my Zantac dosage is showing up as amphetamine on the test? I don't know anything abut drug tests but I am sure this particular test is a general kind of test for a company just checking to see if their employees are using illegal drugs. I take 300 mg daily (150 in the morning and 150 at night). The Rx cream I put on my face is Cutivate (I just smear about 1 inch worth on my cheeks and chin twice a day for a rosacea skin problem). I hope you can suggest a test I can take or steer me to some info about the Zantac. I appreciate any help and any news you can send me. Thanks. Oh yeah, I also use Selsun Rx and T-Gel as my shampoo on alternating days in the shower (for seborrhea).

Answer:  You should check with the company doing the test for interactions. These will be listed. Neither should test positive in most drug testing.

Detecting Steroid Use [posted 11/17/98]
Question: Would morphine be classified as a narcotic shown up in a blood or urine test?

It is a narcotic and would generally be seen in drug testing.

Detecting Steroid Use [posted 11/13/98]
Question: Can steroid use by injection into the muscle be detected in a urine drug test ?

Answer: Usually, depending on the test and what they are looking for.

Alcohol Breath Test While on Medication
Question: I have been taking Lorcet 10/650 for a year now to control pain associated with scar tissue buildup after having a Laminectomy of L4-5, L5-6 etc. I am currently undergoing PT to relieve some of the pain in order to decrease my dependency on medications in the future. The question is in reference to the respiratory effects of long term use in a very odd context. A few months ago I was stopped by the Highway patrol for driving with my high beams on. When the officer smelled beer on my breath he proceeded to give me a series of tests to determine my sobriety. Although I past all mental and most of the physical tests he opted to take a breath test. I had told him exactly how many beers I had consumed (4) and the last being drank 40 min prior to the test. He did not believe I was to impaired to drive but when we took the breath test to both of our surprises it registered as if I should have been stumbling drunk. Can Lorcet because it effects the respiratory system alter the way in which the lungs process alcohol form the blood giving a false impression of blood alcohol content either direction higher or lower but none the less altering the result and therefore making this type of test unreliable as evidence. My lawyer says that his expert would not have an opinion on this because the question has never been raised in a court case. Can anyone out there offer a opinion in this matter?

Answer: Wouldn't usually affect metabolism.

Drug Interactions Throwing Test Off
Question:I work with a methadone clinic, recently we have had trouble with the drug PCP showing on clients testing that have to be a mistake due to the amount of results alone. We are trying to find out what could cause this result. So far we have discovered Promethazine and Elavil. I would appreciate any other drugs, OTC, or prescription that could cause these results. It is not a "legal" matter only an opinion, based on materials available to yourselves.

Answer: Best to check with the manufacturer of your drug screen. They will have a listing of potential interacting drugs and false positives as well.

Did My Dental Visit Cause My Positive Drug Test [posted 10/28/98]
Question: I have recently had a drug screen test. The results came back sustained so the doctor sent them back to the lab for re-testing and the results came back with portions of fedamine 93% accurate and 7% inaccurate. I told the doctor before taking the test that I was using medication due to sinus problems. I have been fired from my job due to this I offered to take another drug screen test but they said that I need to pay them 150.00 dollars to send the test back to the lab and if it comes back negative then I can have my job back. Did the medication that I took do something to the urine to make it come out positive. please I need some answers the doctor will not return my phone calls. Thank you for your help, God bless.

Answer: Possibly, it depends on the test and the amount of medication you were taking. Screening tests are cheap but, have error. More specific tests cost more money. This is why they are asking for the $150.

Did My Dental Visit Cause My Positive Drug Test [posted 10/28/98]
Question: I have recently failed a drug test for employment, testing positive for "large amounts of cocaine". This is astonishing because I have never even seen the drug. When I scrutinized my schedule for the days prior to the test, I remembered that I went to a dental appointment (cavity). Is there anything used in a Dental office that could test positive for this on an "EMIT" and/or "GC/MS" urinalysis?

Answer: Some dentists could use cocaine to stop bleeding also the xylocaine could be picked up depending on the sensitivity of the test. In general, this would be my guess since most offices have stopped carrying cocaine due to monitoring requirements(ENT about the only exception).

False - Positive Drug Test [posted 8/11/98]
Question: Recently I started a new job with a large company. On my first day they sent me for a physical and a drug test. Four days later, I was being walked out of the building for testing positive for cocaine. I don't use illegal drugs. Are there any over the counter, or prescribed products that would give a false/positive result for cocaine? My career is on the line. I have heard Codeine, Benzoyl Peroxide, Tylenol 3, poppy seeds, Lanocane Cream, Nasal Sprays, and acne fighting products could have this result. Is any of this true and what other products and medications would show up as a positive result?

Answer: You will need to find the company that performs the testing and find out their cross-reactivity. Each one is different depending on the type of test used. This is published by the company that makes the test.

PCP (phencyclidine) - False Positive Tox Screen [posted 7/30/98]
Question: My wife recently had a baby. She was under a doctor's care for the treatment of bronchitis. She was prescribed hydrocodone which is a cough reflex suppressant. She was also prescribed erythromycin. Four days before the birth, she had a tox screen and tested positive for PCP (phencyclidine), which alarmed the doctor. When the baby was born she tested positive for opiates from the hydrocodone. So, CPS (child protective services) was called. They took my three year old from her baby sitters that day and the new born from the hospital when she was released. Anyway we had heard from an ex-lab technician with a pharmaceutical company that there is a preservative used with hydrocodone (propametholyne glyclo) that produces a false positive showing of PCP. I have yet been able to confirm that. I've contacted the manufacturer of the medication and they can't identify that. Do you have an answer for me as to what happened. She has never taken PCP in her life, nor has ever seen it. My wife listed the medications she was taking as, Loritab 7.5/500, Phenegan 25, EryTab 333 mg and Tylenol #3 with codeine. Is there something in the combination that might be the culprit?

Answer: I would contact the manufacturer of the drug test and find the cross reactants to the PCP. They have a list of these medications and they vary markedly by company. As to the narcotics, child protective would not be interested if it was truly prescribed. The PCP is the issue.

False Positive on Drug Screen
Question: Regarding blood test screening for THC, what prescription medications are known to cause false positive results? Particularly, have Prilosec or Propulsid ever been know to do so?

Answer: It really depends on the specificity of the test. There are expensive and less expensive screens, but the specificity drops with the cost dropping. In general, drug urine screens do not cross react with prescription drugs unless they belong to the same class of drugs. I would not expect any cross reaction between these drugs and THC.

Drug testing
Question: I recently did a drug test for a new job and the results came back positive for amphetamine. At the time, I was on three prescribed medicines: vicodin, cephlix and robaxin. Can one of these three prescriptions given this result? I need to know because I asked that they redo this test. If one of these medications is the reason for the result than I can give this information to them.

Answer: Of these medications, the most reasonable is robaxin. This is a muscle relaxant and although it is not an amphetamine, some of its ring structures could be picked up if the test is not specific. Ask that a more specific test be performed. This will definitely identify amphetamines. Usually drug screens in companies are inexpensive to keep costs down. These pick up several false positives at the price of being less specific. However, I doubt that the company will spend the cash to do the test. You may have to pay for the test.

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