Taking Nyquil And Sudaphed For Cold And Meklazine. Test Showed Positive For Methamphetamine. Cause?

Posted on Sat, 20 Apr 2013

Medically reviewed by Ask A Doctor - 24x7 Medical Review Team

Sat, 20 Apr 2013 Answered on

Mon, 13 May 2013 Last reviewed on

Question : I take Meklazine daily. I had a procedure done on Wednesday they used Versed. Also have been sick taking Nyquil and Sudaphed for my cold. Today I had to take a ua. The tech said it was positive for methamphetamine. I do not use any drugs, is it possible something I have been taking could have made a false positive?

Answered by Dr. Jonas Sundarakumar (1 hour later)

Hello and welcome to Healthcare Magic. Thanks for your query.

Though urine drug screens are usually accurate and specific to the substance that is being screened for, sometimes, there can be false positives.

Among the medication which you have mentioned, Sudafed contains "pseudoephedrine" and it has been reported that this can sometimes give a false positive test for amphetamines.

Urine drug screens actually detect the metabolitites or break down products of the drug in the urine. Rarely, the metabolites of some other substances can have similar molecular structures and hence reslt in false positives.

So, if you are sure that you have not taken any drugs, you can inform the lab that you have been taking Sudafed recently and maybe, request for a re-test or a blood / hair test.

Wish you all the best.

Regards,
Dr. Jonas Sundarakumar
Consultant Psychiatrist

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar