Questions about False Positives in Drug Testing, page 211

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 this forum is not for medical or legal advice.

False positive for pcp?
Date: 6/24/2012
I get u.a.’d multiple times a week, recently my test have been barely showing a negative for pcp….what could cause a false positive for pcp? I take ultram, i.b.u. and a vitamin. Does ultram show in a gcms testing?


AskDocWeb: Ultram shows up only as Ultram on the GC/MS test. On the initial urine test, only a few substances have been documented to sometimes show up as a false positive for PCP: Diazepam, Diphenhydramine (Benadryl, Tylenol Simply Sleeps, and some formulas of Theraflu), Doxylamine, Effexor Tablets (venlafaxine hydrochloride), Ketamine, and Lamotrigine.

Camel Crush?
Date: 6/26/2012
I jst went for job interview and failed my drug test it came postive for cocanie i nver used this it was a saliva test but i smoked a cigg camel crush before i took it would that made me fail


AskDocWeb: Camel Crush cigarettes contain a blend of Virginia and Turkish tobacco. They have not been reported to cause false positives for cocaine.

Question about Adderall and hair test
Date: 6/26/2012
Hello, hoping to get another opinion. Searched the web over and over and seen this question answered both ways, yes and no. Please review and let me know what you think: Will a one time (ever) 10mg use of adderall show up on a hair follicle test? IE: even detected at 100pg/mg? or show up above the cutoff of 500pg/mg hair indicating use? Additional Info: – Taken with alcohol – Taken on a very warm summer day, sweating, walking around entire time after ingestion – Male, 6 ft., 165 lbs, fast metabolism, thicker dark hair grows fast, white ethnicity, exercise and cardio around 4 times/week. – From time of ingestion to time of test may be approximately 1-2 weeks – Zero other drugs taken in past 5-6 years


AskDocWeb: To our knowledge a definitive answer to your question is not possible given the existing published research. A single dose of Adderall “can” show up on a hair test but the level at which it would show up is unknown.

Negative results
Date: 6/26/2012
hello, i was wondering. I take percocet 10s and i also take fentanal 25 mg and my urin test at my pain clinic showed my results were negitive for all drugs. I do not understand. I take all of my meds as directed and i also just found out that I am two weeks pregnent. can this effect my test results if not what else can cause this?


AskDocWeb: Pregnancy has not been reported to have any effect on drug testing for drugs of abuse. However, there are several reasons for testing false negative:

  • The drug was not taken as prescribed.
  • Drinking an unusual amount of water can dilute the test sample. A diluted sample may not have the concentration level that is needed to show that you are taking the drug.
  • Some people metabolize drugs exceptionally fast and if the last dose was taken too long ago it might not show up.
  • A small percentage of drug tests are faulty.
  • If the drug you are taking has a very short half-life and if the last dose was taken too long ago it might not show up.

One solution for this situation is to request a blood test so that they can get a more accurate result.

How long does Xanax stay in my system?
Date: 6/27/2012
I am a patient at a pain clinic and they do not want their patients to take benzos I had a death in my family and took 2 .5mg xanax how long does it stay in my system…


AskDocWeb: That depends on the person. The manufacture states that the half-life of Xanax is a maximum of 26.9 hours. Most drugs clear your system in about 5 half-lives but some drugs take longer. Also it varies from one individual to the next. As long as you’re well hydrated and have a healthy elimination system it should be out of your body within 6 days. (26.9 times 5 = 134.5 hours or 5.6 days). You may still have some in your system at that point but it should not give a positive result.

Date: 6/28/2012


AskDocWeb: Just so you know, when you use all capital letters like that you seem to be shouting hysterically and people will pay less attention to what you are saying.

Three of those, Fluoxetine, Hydrocodone, and Omeprazole, have shown up as false positives on urine tests but not for meth. To find out if his test was thrown off by a false positive or not, he would need to get additional testing, typically with a GC/MS confirmation test.

Indomethacin and ibuprofen
Date: 6/28/2012
I have been taking Indomethacin 75mg and ibuprofen 800 will it show up positive on a drug test?


AskDocWeb: Although false positives are rare, several sources say that Ibuprofen might show up as a false positive for marijuana (THC). Be sure to tell them what you are taking and make sure that they make a note about it.

Tested positive for amphetamines
Date: 6/29/2012
Hello, I am in DUI court and get drug tested 3x a week. I have tested positive for amphetamines 3x. I had to go to jail for 5 days for the first positive and have had 2 more since then. I dont understand what is causing this.I have had a cold for a couple weeks. I have taken mucinex and tylenol cold & flu severe, benadryl, can these cause positive for amphetamines?


AskDocWeb: According to Redwood Toxicology Laboratory (one of the nation’s premier forensic drug testing facilities), Tylenol Cold (combination) may test positive for amphetamines (Reference: 33). Since the results of their drug testing provide legally defensible results you may want to get your sample sent to them for a confirmation test.

Date: 6/29/2012
Can metformin make you fail a pre employment drug screen?


AskDocWeb: No.

Hair follicle test
Date: 6/29/2012
I have a 2 year old son who just had a hair follicle test and it came back that he had methamphetamines in his system but he has never even been around that drug and my botfriend nor I have ever used either. My son had a cold a couple months ago and was taking some cough medicine and also was perscribed with am albuterol inhaler. What would make him test positive?


AskDocWeb: For the safety of your child it is important to get a confirmation test to find out if the original test was a false positive or not. You may not be able to identify the cause but if it was a false positive then a GC/MS test would come back negative. If there really was methamphetamine in your son’s system then you have several serious problems.

Prilosec OTC
Date: 6/29/2012
Have been taking prilosec otc and had walmart urinalysis, will that show up?


AskDocWeb: It is possible, several PPIs have been noted to sometimes show up as marijuana (THC) so be sure to tell them what you are taking before doing the test.

Catnip and rescue remedy
Date: 6/30/2012
I am 20 wks pregnant and use catnip as well as a tincture called rescue remedy to control anxiety. the hospital that I am having my baby at urine drug tests all women. Will these give a false positive?


AskDocWeb: The catnip should cause no problems but Rescue Remedy is questionable. A chemical dependency counselor reported that her director stated that Rescue Remedy has tested positive for benzodiazepine. Although we were unable to find a reference that would indicate Rescue Remedy might cause a false positive for benzos, if you suspect a false positive we suggest that you get a confirmation test. The gas chromatography/mass spectrometry (GC/MS) test is commonly used to determine false positives so be prepared to get one if anything shows up.

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