Drug Infonet provides drug and disease information for your healthcare needs. Visit our FAQ page to find answers to common health questions. Look on the Manufacturer Info page to link to pharmaceutical company pages. Click to Health Info and Health News for the latest in healthcare developments.
Drug Infonet brings this free resource to you so that you become a more informed consumer of healthcare.
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
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
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
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
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
Question: Would morphine be classified as a narcotic shown up in a blood or urine
Answer: It is a narcotic and would generally be seen in drug testing.
Detecting Steroid Use [posted
Question: Can steroid use by injection into the muscle be detected in a urine drug
Answer: Usually, depending on the test and what they are looking for.
Alcohol Breath Test While on
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
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.
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.
Back to Drug InfoNet Home Page.
Back to Doctor FAQ main page.
Send your impressions, comments, thoughts, etc. to firstname.lastname@example.org