Feedback on False Positives from Drug Testing, page 51

False Positives Forum

This forum is intended to help those who Do NOT Abuse Drugs. We do NOT support the illegal use of any substance. If you have experience with false positives, share your experience. What would you tell someone about drug testing and false positives? Please remember that we do not give medical or legal advice.

Subj: Zantac
Date: 11/25/2008
I just failed a drug test I was tested postive for amphetamines I dont take them. I’ve taken zantac for over a year for heartburn could that of caused it? Does zantac cause a false postive? I’ve also taken advil pm


AskDocWeb: Zantac has been reported to sometimes show up as a false positive for Amphetamines (Ref: 30)

Subj: Hydrochlorothixzide and Zantac
Date: 11/27/2008
Hello, Recently was at a wrong place at the wrong time, needless to say I have probation with supervized urinalisis now…well I have been clean for approx.20 years, EXCEPT, two weeks ago, my doctor heard a heart mur-mur; also high blood pressure and also have gastriel ulcers…so what meds I was on while the pee test failed for METH was; HYDROCHLOROTHIXZIDE…and ZANTAC…PLEASE, PLEASE I BEG OF YOU, GET BACK TO ME ASAP..WILL THESE MEDS ACTUALLY FAIL A METH U-A TEST? Thank you for your knowledge input..(once its sent back)


AskDocWeb: Neither has been reported to cause a false positive for meth although Zantac sometimes shows up as a false positive for Amphetamines.

Subj: The difference between Methamphetamine and Amphetamine
Date: 11/27/2008
In September I was taken in and arrested on suspicion of DUI (for getting lost and ending up at the Back Gate of Camp Pendleton Marine Core Base and they totally overreacted) Anyways, they did a blood test and at my first hearing I was told that amphetamines showed up in my blood. Well DUH, I take Adderall for ADD/Narcolepsy with a legal prescription which I told the Officer. At my second hearing I was informed that Methamphetamine showed up in my blood as well. I don’t use illegal drugs. I did drink a total of 4 different energy drinks that day (it was a long day for me) One being a tall AMP made by mountain dew, a NO FEAR, a smaller AMP 88, and the other one was a more healthy type I know because it was covered on my food stamp card, unlike all the others. I also helped pull weeds all day which caused my allergies to be so bad that I took a Clariton and had to use my Albuterol inhaler quite a few times. The Energy drinks are what concern me the most, as well as Adderall, but what is the difference between Methamphetamine and just Amphetamine? IN A BLOOD TEST. Or is it possible that The Police Department ran my Urine Sample (even though the Officer said I didn’t fill it enough to use- that’s why they drew blood).


AskDocWeb: Methamphetamine is the parent drug. Once in the body methamphetamine metabolizes (or changes) into amphetamine so a positive result for amphetamine can also be interpreted as a positive test for methamphetamine. Both methamphetamine and amphetamine are excreted in the urine.

Subj: Question about Ibuprofen?
Date: 12/2/2008
How does one prove one was taking Ibuprophen – an excess amount – friend tested positive on a random drug test – he is in recovery for 11 years and I myself for 27 years. It there any “literature” that states that Ibuprophen does cause false positives for THC? Something from an actual medical journal or book. When he spoke to the “drug” MRO secretary – “she said I never heard of a false positive” there is no such thing – now this is a medical professional (young at that but still a medical professional. Meanwhile – job loss. WOW – he got recovery and get tested positive for something he did not do and we have no way to prove otherwise. Yes he is aware that the “common thing one says is “oh yes he relapsed” – Well NO HE DID NOT – All he took was ibuprophen. Again is there any medical journals recent that we can reference when we speak to unemployment and/or the labor board. Thank you very much.


AskDocWeb: That is what is listed in the references. For Ibuprofen see numbers 1, 3, 16, 18, and 29.

Subj: Amoxicillin and tomatoes
Date: 12/3/2008
I just watched an episode of the show Eli Stone in which a doctor, looking to explain her positive test, claimed any first year med student knows that amoxycillin creates a false positive for cocaine, which she was taking for an ear infection. I thought that sounded like a bunch of hooey. Is it? Or did the writers get it right?


AskDocWeb: It appears that the writers got this one right. Sometimes what seems like hooey actually turns out to be true. We were at a friend’s house recently with a group of people where a woman complained that the tomato plant she was growing in her south window never developed any tomatoes. It produced lots of flowers but no tomatoes. One of the guests pointed to the lady’s cat and announced, “There is your solution. Just pick up your cat and rub the cat’s tail on the flowers. Do that and you’ll get tomatoes.” The woman became very indignant and demanded to know why the guest was treating her like an idiot. Her first impression was that the solution sounded like hooey. After all, what in the world does a cat’s tail have to do with growing tomatoes? Of course after it was explained to her that indoor flowers need to be hand pollinated in order to produce tomatoes, then it was obvious that it would indeed work, even if it were a bit unorthodox.

Subj: This isn’t right
Date: 12/4/2008
Hi there. Recently I’ve test positive for cocaine on a UA I had this past November 24th. I have never done cocaine in my life and was arrested for a DUI I had back in January. Needless to say, I’ve been nothing but good/honest with my PO/the system, have done everything by the book and than my PO calls me “2 weeks” after the test is done to tell me that I need to come in and fill out a report as to when and why I did it. I told him “NO” since it wasn’t true. Anyway, long story short, since January, I’ve given up drinking entirely and started taking a multi-vitamin(like centrum), niacin, and vitamin c once every morning and fish oil (3x a day/morning, noon, and night as the bottle suggests/with meals)…can anything with these supplements create a false positive for cocaine? I want to prove my innocense/am completely outraged by this false accusation/plus this caused me to stay on probation longer when the court said I could receive early release for good behavior which I’ve been! Please, any help would be greatly appreciated to prove my innocense. This test also wasn’t sent to a state lab per the county supervisor/it was done on the spot and my PO found out about my “positive” reading the day after he took it/yet waited 12 days to let me know that I tested positive. This isn’t right/PLEASE HELP ME!


AskDocWeb: Sorry Jim, none of the supplements that you list have been reported to cause a false positive for cocaine.

Subj: False positive for ketamine?
Date: 12/4/2008
What substances can cause a false positive for ketamine?


AskDocWeb: There are no substances (that we know of) that would cause a false positive for ketamine.

Subj: False positive in a urine drug test
Date: 12/5/2008
I’m looking for a list of products that would cause a false positive in a standard urine drug test. I am on parole and do not wish to have a false positive.


AskDocWeb: That is exactly what we list on this page.

Subj: Fluoxetine and Zyprexa
Date: 12/5/2008
My son tested positive for barbiturates, but swears the only thing has done was marijuana. He is on Fluoxetine and had taken Zyprexa within the last 3 weeks before the test. Can this cause the false positive?


AskDocWeb: According to Robert Hsiung, MD, University of Chicago (, Fluoxetine (Prozac) sometimes shows up as a false positive for amphetamines. Zyprexa has not been reported to show as a false positive on urine drug tests.

Subj: Trileptal
Date: 12/5/2008
I am a substance abuse counselor in Maryland and have recently had a string of clients who were here for various substances-from alcohol to heroin but no previous use of benzos. Some of them have shown positive for benzo’s but deny their use, but they all take varying amounts of Trileptal. Could this be causing false positives for benzo’s?


AskDocWeb: Sorry Chris, there are no reports on Trileptal.

Subj: Positive for THC
Date: 12/7/2008
I had a urine test come back positive for THC, I take Nexium, Promethazine, and have Vitamin B2 in my daily multi-vitamin, is this the reason?


AskDocWeb: Both Promethazine and vitamin B2 have been reported to sometimes show up as a false positive for THC.

Subj: Opana
Date: 12/8/2008
Can Opana cause a drug test to come back positive for Morphine??


AskDocWeb: Opana is not on our list. The only substances that we have been able to document as causes of false positives are listed here.

Subj: GC/MS confirmation
Date: 12/9/2008
GC/MS confirmed the presence of Methadose, Xanax and Darvocet (by virtue of norpropoxyphene metabolite, not propoxyphene) in UDT sample. Subject has two current prescriptions and an old one for all these drugs but swears not having knowingly taken propoxyphene in several years. Patient consumed almost 120 ml of store brand Robitussen (expired last month) in 2 days prior to drug screening. Subject was also using Sudafed, Afrin and chloro-tabs in 10 days prior to sample. RMO says none of the other medications listed as taken in the last 5 days: Topomax, Remeron, Restoril, Ciprofloxin, Valtrex, Cyclosporin could explain the GC/MS confirmation of Darvocet. Is there any way to explain how this confirmation for Darvocet could have occured without having ingested the medication? Can norpropoxyphene metabolite be cross-synthesized in the body through any of the Px/non-Px meds listed present? Is there any possibility that the old Robitussin was patially decomposed and could have influenced the subject’s metabolism and/or test to produce a false GC/MS confirmation for Darvocet?


AskDocWeb: Sorry David, although we have not heard of that happening, the analysis of cross-synthesized material is beyond our expertise.

Subj: Risperidal?
Date: 12/11/2008
I go to a pain clinic for chronic back pain. Currently I take MSContin, Cymbalta, Valium, Topamax, and occasional Zanaflex. I was told that besides my valium, another benzo came up in my system (Risperdal) and also a larger amount of hydrocodone. I was in shock. I asked if the Zanaflex could be the culprit, but the PA, of course, said no. As for the MSContin, I don’t know what to say about that. I take it as prescribed. I read on this site that the Zanaflex CAN show up as a false-positive as a benzo, but why would the PA say Risperidal? Help.


AskDocWeb: Sorry Kelly, we make no attempt to explain the actions of your local PA. However, we have no record of Zanaflex causing a false positive for benzo.

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