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Blood test showed positive for phenobarbital. Worrisome

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Practicing since : 2003
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I am an md straight as an arrow does not drink or take drugs. I was randomly checked for a drug screen and was positive for phenobarbital. I did not take any phenobarbital as Donnatal or the like. I did have an herbal tea during that week for sleep call nighty night from Stop and Shop. Now I may be in trouble. Any help?
This is incredible that I have to succumb to this. Any help? Had Zofran in the Er for Noro virus gastroenteritis. O/w neg for drugs.
Posted Sun, 17 Mar 2013 in Drug Abuse
Answered by Dr. Jonas Sundarakumar 2 hours later
Hello and welcome to Healthcare Magic. Thanks for your query.

I'm sorry to hear about your situation. If you are certain that you have not taken phenobarbital, then the result is probably a false positive.

Now, a false positive can occur with any test and among the various drug screens, barbiturates and benzodiazepines have relatively higher rates of false positivity. You should also remember that a drug screen detects a specific drug by actually identifying a particular chemical structure, supposedly unique to that drug. So, it is possible that certain other substances / medication or their metabolites may coincidentally have a similar chemical structure, which in turn may lead to a false positive for the drug. So, it could be possible that the herbal tea / sleeping aid which you took could have contained such a chemical moiety. False positives can also occur due to contamination of the sample.

So, in your current situation, you can ask for a repeat drug test. You can also report all your prescription and OTC medication to the authorities and maybe, ask the lab to test the OTC sleeping aid to check for the possibility of a false positive result due to it.

Wish you all the best.

Dr. Jonas Sundarakumar
Consultant Psychiatrist
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