Feedback on False Positives from Drug Testing, page 62

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: Tested positive for Oxymorphone
Date: 4/14/2009
I am a chronic pain patient (failed back syndrome) currently taking 10mg of methadone daily and 10mg percocet “as needed”. I took 2 percocets the day before my last urine drug screen (1 month ago) and today was told I tested positive for Oxymorphone (ms) 226 ng/ml. I was told this can only be positive for the drug Opana, which I do not take, but took for 5 days over 6 months ago which was prescribed by my pain clinic. Can percocet test positive for Oxymorphone? Any feedback is appreciated, thank you.


AskDocWeb: Although we haven’t heard of it showing up as Oxymorphone, Percocet will test positive (not false) for opiates.

Subj: Paroxetine?
Date: 4/15/2009
I recently tested positive for THC but don’t smoke. Is it possible that paroxetine could have caused a false positive?


AskDocWeb: Paroxetine has not been reported to show up as a false positive.

Subj: False/positive U.A.’s
Date: 4/15/2009
I was wondering if the perscription drugs, Fynthroid or Tamoxifen for thyroid and cancer can cause false/positive u.a.’s.


AskDocWeb: None have been reported.

Subj: Gilbert’s syndrome
Date: 4/16/2009
I do not use cocaine, but I know I come into contact with it at times due to my job as a public servant. I recently came up positive for cocaine and am floored. They say that the GC/MS came back confirmed as well, an initial test was the KIMS. I have read about kidney and liver problems causing false positives and after the pop, went and found out that I have Gilbert’s. My questions are, can this ‘benign’ syndrome throw off my body that much, or cause any exposure outside of the ‘normal’ timeframes to last longer. MY Gastro Dr says he has not heard of it, but did not discount the possibility. Any information would be greatly appreciated. The tests were not conducted by a HHS certified lab, but by DoD.


AskDocWeb: We have no information that would suggest Gilbert’s syndrome might cause an increase in the length of time someone would test positive after exposure to cocaine. If future readers have any information on this maybe they can help out here.

Subj: Methadone
Date: 4/16/2009
What does methadone show up as on a 12 scale UA? Does it show up as an opiate?


AskDocWeb: Yes, methadone contains synthetic opiates.

Subj: Chance of losing his job
Date: 4/16/2009
I need help. My step father took a UA for his job. Well it came back positive for weed. Everybody who knows him knows that is an impossibility. He has a good chance of losing his job and everything he and my mother could lose everything. I just need to know what kind of meds could he have taken to get this false positive.


AskDocWeb: Everything that has been reported to cause false positives is listed here.

Subj: Hydrocodone
Date: 4/16/2009
Can my prescribed hydrocodone be causing a false positive on my home THC tests?


AskDocWeb: It is possible because hydrocodone bitartrate contains synthetic opiates.

Subj: Tizanidine and Magnacet?
Date: 4/17/2009
Will either of these two medicines cause a false positive urinalysis? Tizanidine and or Magnacet. Thank you,


AskDocWeb: Neither has been reported to show up a false positive on urine drug tests.

Subj: Non-negative for PCP
Date: 4/17/2009
Today a friend of mine at work tested “non-negative” for PCP in a random urine drug test. What OTC or prescription meds could cause a false positive result? She’s taking Ambien and Effexor (not sure of spelling…it’s an antidepressant) and a hormonal compound for a thyroid condition. Not sure what’s in that. Any thoughts?


AskDocWeb: A false positive for PCP is rare but it does sometimes happen. Effexor Tablets (venlafaxine hydrochloride), Ketamine, Diphenhydramine, and Diazepam (generic name for Valium) have all been reported to sometimes show up as a false positive for PCP.

Subj: Tested positive for methamphetamine
Date: 4/19/2009
I have tested positive for methamphetamine on a urine test. I have never used any illicit drugs. I take micardis plus, atenolol, and amlodipine (as besylate) for hypertension. I have not used any other medication for at least 2 weeks. What could cause this result? Thanks,


AskDocWeb: Sorry J, none of those are on the list.

Subj: Positive for heroin
Date: 4/20/2009
My mom was on the methadone program for some pill abuse, when they gave her a urine test they said it was positive for heroin. She has NEVER taken the drug in her life. She was taking laxatives would this cause her to test positive for something like this?


AskDocWeb: There are several things that may show up as heroin on a urine drug test. Here is the short list.

  • Acet-AM
  • Amesec
  • Bronkaid
  • Bronkotabs
  • cold and cough remedies with dextromethorphan
  • Estasule Minus
  • Morax
  • poppy seeds
  • Quadrinal
  • Quelidrine
  • Quelichine
  • Quibron Plus
  • Romilar
  • Silexin
  • Tedral
  • Trucal
  • Tussaminic
  • Tussinic
  • and some antibiotics

Any of the above may be correctly identified as a false positive by a GC/MS confirmation test.

Subj: Tested positive for cocaine
Date: 4/22/2009
I am in a substance abuse program, four days from graduating. I gave a urine drug screen and was told tested positive for cocaine. I was floored as I have not been using any kind of drugs for 1 1/2 years. I recently had a bought w/spider bite and hives which I took massive amounts of Benadryl. Would that affect my urine? Please help, as I don’t know what to do. Now they tell me I am not graduating.


AskDocWeb: Benadryl (Diphenhydramine) has been reported to show up as false positives for Benzodiazepines, PCP, and Tricyclic Antidepressants 2-4 days after a single use. (Reference 45).

Subj: Trazodone?
Date: 4/22/2009
Will trazodone show as a benzodiazepine on a urine test for probation? I also did some research on the Internet and found this: Triazolo pyridine (1 word) – Trazodone Triazolo benzodiazepine (1 word) – Xanax. Could the fact that both drugs are chemically or structurally alike? Would this cause a false positive?


AskDocWeb: There are no reports about trazodone causing any false positives. Maybe a reader can help you out with this one.

Subj: False positive for percocet
Date: 4/23/2009
I recieved a false positive for percocet, I am prescribed vicodan, hydroxyzine pamoate and naproxen can this cause it? Thank you much.


AskDocWeb: Vicodin ESĀ® contains synthetic opiates which might be misidentified by a urine test but a GC/MS test should clear that up.

Subj: Refusing to drug screen
Date: 4/23/2009
My ex is refusing to drug screen because she is sure she will have a false positive from the Ritalin and Vyvanse she is prescribed. Would a GC/MS be able differentiate between those and Meth?


AskDocWeb: Yes, false positives only occur in a small percentage of tests and the GC/MS test correctly identifies those false positives.

Subj: Tonic water
Date: 4/24/2009
I recently failed a drug test for cocaine at work. When I was notified I about lost it since I don’t do, and haven’t done cocaine. I started researching what could be reasons and I came across a lot of sites saying tonic water can cause a false negative. I’ve been on a gin and tonic kick for a few weeks so I assume this is the reason I failed. I’m having trouble finding out why it gives a false indication though and it makes me question if it really could be the reason I failed. So I guess Id like to know if first it really can cause a false screen, and second if so why?


AskDocWeb: We found three sources (26, 29, and 32) that say the quinine in tonic water has shown up as a false positive for opiates but no references that say it might show up as cocaine.

Please note that there are some health concerns with using quinine.

Subj: Cephalexin?
Date: 4/24/2009
I have tested positive for thc in my urine. I have been exposed to thc. I have recently been taking cephalexin could this produce a false positive?


AskDocWeb: Sorry Anita, cephalexin is not on the list.

Subj: Goji berries
Date: 4/25/2009
Will taking goji berries with it’s natural methyl content throw up a false positive?


AskDocWeb: While your concern is understandable, there are no reports of false positives involving goji berries.

Subj: MDMA?
Date: 4/27/2009
I have a deceased client whose autopsy urine tox screens show positives for benzos, methadone and MDMA. He was taking both the benzo and the methadone by prescription. Could either of these have resulted in a false positive for the MDMA?


AskDocWeb: We don’t know but if an answer is required, you can consult a toxicologist.

Subj: Failed a drug screen for benzo
Date: 4/27/2009
Hey I recently failed a drug screen for a benzo and I haven’t used xanax or anything of the sort for at least 2 years. I’ve been taking a generic for of paxil for depression. Is there any way this would cause a false positive?


AskDocWeb: There have not been any reports of false positives involving Paxil.

Subj: GC/MS
Date: 4/28/2009
GC/MS just how reliable/accurate is it. Why would you test positive for cocaine with GC/MS and your split sample tests negative for cocaine?


AskDocWeb: That is because the GC/MS test is much more accurate. It can identify many things that other tests miss.

Subj: Concerta?
Date: 4/30/2009
My son is on concerta 54mg and got drug tested swab in mouth and came back positive for cocaine. He has been on concerta for 8 years, can this happen?


AskDocWeb: There are antidotal reports of Concerta showing up as meth but not cocaine.

Subj: Legal herbs?
Date: 5/1/2009
Kratom, Damiana, Kava kava, Salvia, Blue lotus, hawaiian baby woodrose seeds. Is it possible for any of these legal herbs to test false positive for any illegal drugs?


AskDocWeb: None of those are on the list but we did find references for Black Pearls (Tung Sheuh pills), Chinese herb pills, Cows head pills (Chinese herb), Hempseed Oil, Ma Huang (Ephedra sinica), Potentsex pills (Chinese herb, Poppy Seeds, Valerian Root, Valerian extract, and ordinary tonic water.

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