Questions about False Positives in Drug Testing, page 205

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.

Positive for cocaine
Date: 5/29/2012


AskDocWeb: Please adjust your “Caps Lock” key so that you don’t appear to be shouting. Neither of your prescribed medications have been reported to cause false positives for drugs of abuse.

Date: 5/29/2012
I just had taken 3 ibuprophen 200 mg a pill can i fail a saliva test


AskDocWeb: It looks like there is a possibility. Ibuprofen (sometimes spelled Ibuprophen) has been reported to sometimes show up as a false positive for THC or Marijuana.

Can Sudafed show up as meth?
Date: 5/30/2012
I am concerned with my sister doing crystal meth. I purchased a home drug test kit and haven’t used it yet. She says she took sudafed and it will show up as meth on the drug test. Is that true? If so, can you determin if it was really meth or sudafed w/any certin test? Please let me know. I need your help.


AskDocWeb: While Sudafed has been reported to sometimes show up as a false positive for amphetamines or ecstasy, it does NOT show up as meth.

Cephalexin or Tylenol 3
Date: 5/30/2012
I have a defendant testing positive for benzodiazepines. she is taking cephalexin and tylenol 3. would anything she is taking cause a false positive.


AskDocWeb: According to Dr. Martin S. Spiller, Tylenol 3 may cause positive for opiates. Cephalexin has not been reported to cause problems with drug testing for drugs of abuse.

Traces of cocaine
Date: 5/30/2012
I have never used any illegal drugs in my life; today I took a urine test for a job and was told it was positive for traces of cocaine. I take blood pressure medications and natural supplements. Sometimes I take ibuprofen for joint pain – can any of these cause a false positive reading?


AskDocWeb: Here is the current list of the causes for a false positive (non-negative) urine drug test result:

  • Amoxicillin
  • Ampicillin
  • Antibiotics
  • buprivacaine (Marcain, Marcaine, Sensorcaine and Vivacaine)
  • Cola tea, cola leaf, cola flour, cola oil
  • Tonic water

Please note that those with diabetes or kidney disease have also tested false positive for cocaine so if there is any doubt, get a GC/MS confirmation test to rule out non-negative results.

Tested positive for THC and PCP
Date: 5/30/2012
I take 300 mg of Effexor daily along with 3600mg of gabapentin (Neurontin). i have falsely tested positive for THC and PCP several times. I have not used either of those drugs. Also for the past week ive been prescribed Benzonotate (Tessalon) for a persistant cough. Could this show as a false positive for a benzodiazapam? Thank You for your time!


AskDocWeb: According to Blue Grass Drug Screen, which is the drug testing company used by US military, Effexor may show up as PCP. Since it appears that you suspect you tests results of being false positive, we suggest you get a GC/MS confirmation test.

Energy drinks
Date: 5/30/2012
I took an oral swab test for my probation officer and it came back positive for cocaine. I havn’t done cocaine or any other drug and now am facing real trouble. The closest thing ive done to getting high was drinking energy drinks. I told them i didnt use cocaine or any other substance and they sent the swab to be confirmed. could the energy drinks cause a positive cocaine result?


AskDocWeb: Several people have reported getting false positives after consuming energy drinks but so far there is no documentation to confirm that an energy drink might cause a false positive test result.

Failed for benzos
Date: 5/30/2012
I have failed 2 drug tests for benzos in the last 2 weeks at probation. The last time I took any kind of anti-anxiety medicine was about 8 weeks ago. In the past 2 weeks I have taken ibuprofen, Benadryl & tylenol PM. Also I’ve been taking Augmenten anti-biotics & some prescription eye drops for pink eye. I just don’t understand why I keep failing for this!


AskDocWeb: Hi Niki, welcome to the forum. Of the products you list, the most likely candidate is Benadryl. It contains Diphenhydramine, which has been reported to sometimes show up as a false positive for benzodiazepine. A GC/MS confirmation test should eliminate that type of false positive.

Starkers 2
Date: 5/31/2012
I’m taking starkers 2 I’m wondering if I’ll tested positive in a drug test I’m so scared I don’t wanna loose my opportunity at work or school over a supplement pill can someone give some answers pls


AskDocWeb: We don’t have any data on a supplement called “starkers 2” did you mean Stackers 2? If so, check the ingredients in it for ephedra or ephedrine. If that’s not listed then your weight loss supplement is unlikely to cause a problem.

Additional testing
Date: 5/31/2012
I recently failed a ua at my doc for meth and ive never used it. I am taking ranitidine for – heart burn. She sent my urine out to be retested. Will this other test prove I only used ranitdine?


AskDocWeb: That is typically not the purpose of additional testing. Sending the sample out for additional testing is usually done to confirm or deny the results of the original test.

Bendiner & Schlesinger
Date: 5/31/2012
Bendiner & Schlesinger claim to verify positive results with GC/MS but they do not actually perform these confirmation tests.


AskDocWeb: Do you mean that they subcontract that service to other laboratories?

Switch to another medication because of false positive
Date: 6/1/2012
Back in the mid 2000s, I was taking MS Contin for severe pain. I was also taking Effexor for bi-polar… the pain management one month told me I had tested positive for Darvocet! I had no use for the stuff, and no way could I have gotten any-plus taking that when I had morphine was ridiculous. I talked to my doc who recommended talking to my psychiatrist. She told me that indeed studies had shown Effexor to show false positives. I actually had to have her write this out for the pain management who insisted that I switch to another medication in order to get the right urine tests! That sucked because the Effexor was working, but oh well…


Date: 6/1/2012
What Does Phentermine show up as? I take a drug test tomorrow and heard it can show up as positive for cocaine.


AskDocWeb: Phentermine has been reported to sometimes show up as a false positive for amphetamine, methamphetamine or ecstasy but not for cocaine.

False positive for spice?
Date: 6/3/2012
I am in the military and they are currently testing for spice. my test came back positive for spice but i don’t smoke it anymore it has been almost a year. i have read that it can stay in your system for up to 72 hrs, so what could cause this false positive? i have read this is a new test so there has to be some room for error because i don’t smoke spice! please help my career is at stake.

Average Joe

AskDocWeb: You are correct, the test is relatively new, which also means that there is very little data available about possible false positives. The GC/MS test is considered to be the gold standard for determining whether a test result is truly positive or not. Assuming that your test result was a false positive, If you can get a GC/MS confirmation test on the original sample, that should clear you.

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