Questions about False Positives in Drug Testing, page 253

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 amphetamines and methamphetamines
I just received a false positive to amphetamines and meth amphetamines. I have only taken temazepam. I understand that this can create false reading. I need to know if I have had temazepam and I get a positive to amphhet and meth amphet, should I also get a positive to benzodiazepine, which is the type of drug temazepam is tested under. And also, if the temazepam should have been out of my system, could it still cause a false reading??


AskDocWeb: If the Temazepam is out of your system then it would not cause a false positive for anything. Even if it was in your system, it would not show up as amphetamine or methamphetamine.

Is it possible for temazepam to cause a false reading if it is meant to be out of your system?? how many does does it take to get out of your system??


AskDocWeb: Temazepam (Restoril) has a terminal half-life that ranges from 3.5 to 18.4 hours (mean 8.8 hours). Drugs are typically undetectable after a maximum of 5 times the half-life of the longest lived metabolite. The major metabolite of Temazepam (the O-conjugate) has a normal half-life of only 10 hours. The theoretical limit for detection in urine is between 17.5 hours and 92 hours, with an average time to full elimination of 44 hours. However, since Temazepam is excreted mostly in the urine (80% – 90%), any decrease in urological function could increase the detection time.

Can high doses of Clonidine cause false positive for TCH?


AskDocWeb: Although our database lists about 70 possible causes for a false positive for THC Clonidine in not one of them.

I take Lodine … Have not smoked marijuana in 42 days .. Tested positive for THC TODAY ugh


AskDocWeb: As you found out, Lodine may show up as a false positive for THC. You might ask your doctor about using an alternative. If you are treating inflammation and pain caused by osteoarthritis and rheumatoid arthritis there are many alternatives that do not show up on drug tests for drugs of abuse. It might help to let your doctor know that you are being tested for drugs of abuse so that he or she doesn’t prescribe an alternative that would show up on your next test.

Positive for thc
I need help. I tested positive for thc…i had a test three days prior and passed. I did take a couple zanaflex and a couple nerottens for nerve pain. What else could possible causes this?


AskDocWeb: Neither of those drugs would show up as a false positive for THC. However, there are over 70 other possible causes listed here.

Sweet chestnut or Wellbutrin?
I recently had to take a UA for a new job and it cam back positive for thc. is there any chance that sweet chestnut or wellbutrin might trigger a false positive?


AskDocWeb: Wellbutrin has been reported to sometimes show up as a false positive for amphetamines but not for THC. Sweet chestnut has not shown up anywhere in the research on false positives. If you have the option of getting a confirmation test, that is the only way to eliminate false positives.

Failed drug screen
My husband had a drug screen that he failed but they did not know what for, he has presciption for methadone, and takes has recently taken Nyquil, Benadryl, and various types of sinus medications that were over the counter. It was a five panel drug screen. We want to know if they check for methadone at time of screening and is it possible that the other meds made the test look contaminated?


AskDocWeb: The 5-panel urine test (in North America) tests for the SAMSHA-5, which is THC (marijuana), Cocaine, PCP, amphetamines, and opiates. If they just used the one test then it is likely that they didn’t check for methadone. Methadone is a synthetic opioid, which has a chemical structure that is significantly different from an opiate so that wouldn’t show up. However, Nyquil, Benadryl, and various types of sinus medications have been known to show up as false positives on urine drug screens.

Positive for barbiturates
I’m on methadone and i came out positive for barbiturates and i didnt took any med. Wat can cause that positive?


AskDocWeb: False positives for barbiturates are usually caused by anti-asthmatic medications that contain phenobarbital. However, there are a few other possible causes:

  • Fioricet
  • Fiorinal w/codeine
  • Luminal
  • Nembutal
  • Phenobarbitone
  • Phenytoin (Dilantin┬«)
  • Primidone (Mysoline┬«)
  • Secobarbital
  • Seconal
  • Soneryl
  • Tuinal

A GC/MS confirmation test will eliminate false positives caused by the above substances. Please note: If you get a confirmation test that comes back positive, that will usually make your situation worse because it would prove you are guilty.

Tested positive for cocaine!
I’m on house arrest and tested positive for cocaine! I have not used cocaine in almost 2 years… the only thing I’ve been taking is Visalus Science Vi-Shape 1 sweet cream flavor part of Body by Vi Challenge and ibuprofin 600mg. Could this be the reason behind my false positive I have to test 3 times a week, any info on this will be great help.


AskDocWeb: In checking the ingredients of Vi-Shape we didn’t see anything that would show up on a drug test. Ibuprofen has shown up as false positive for marijuana but not for cocaine.

Lab results came back negative?
I have taken 2 drug test for pre employment in a week time and have failed the on site test both times but the lab results came back negative both times. Why?


AskDocWeb: The initial screening for pre-employment drug testing often involves using the lowest cost tests available. It should come as no surprise that the cheap tests are not as accurate as the more expensive tests that the lab uses. A certain percentage of the cheap tests will produce a false positive test result because the cheap tests are not 100% accurate. When the more expensive tests are used on the same samples the lab results come back negative.

False positive for Ecstasy?
I am wondering why I would test positive for Ecstasy in a drug test when I have never taken it? I take trazodone, simvastatin, omeprazole, B/C reclipsin, and Ibprufren for pain when needed.

Ms. P

AskDocWeb: There are about 70 possible causes for a false positive for ecstasy on a urine drug test. Unfortunately none of what you list is known to do that. You might check the big list to see if you missed anything.

I take Soma and have a prescription. Since it is now a controlled substance, what would it show on a 8 panel drug test if it is a false positive?


AskDocWeb: According to The University of Maryland Counseling Center, Soma (carisoprodol) may show up as a false positive for morphine (Reference 43).

Urine tests tampered with?
My sister took a urine sample mc/gs test 4 weeks ago. She tested positive for 15 ng thc. She then took a hair folical test one week later and another urine test. The hair folical test came back negative and it went back for 6 months. The 2nd urine test came back positive with a higher dosage of thc. She took a third urine sample test the following week and it came back negative. How can this happen? Is it possible that the urine tests have been tampered with?


AskDocWeb: While the chance of that occurring is very small it is theoretically possible. It is also possible due to human error, which is more likely to occur at an uncertified lab.

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