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Does promethazine give false positive result during drug screening?

Dec 2012
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Answered by

General & Family Physician
Practicing since : 2012
Answered : 1704 Questions
yes. does promethazine cause a false positive when drug screening is done?
Posted Tue, 26 Nov 2013 in General Health
Answered by Dr. Nsah Bernard 1 hour later
Brief Answer: I do not think it is possible Detailed Answer: Hello, Thanks for posting on XXXXXXX Scientifically, I do not see how that is possible given that the chemical composition of both substances differ. Promethazine is a derivative of phenothiazines where as meth is a derivative of methamphitamines. Personally, I have not come across such results due to the fact that the patient was taking promethazine. If you are not on any other medications, then it is possible that false positivity can still result but not necessarily due to you taking promethazine but rather an error from laboratory. It will be best to repeat test after a couple of days while in the meantime, you increase your fluid consumption. You will have to continue taking the promethazine (even if the test has to be repeated) so if test comes out negative, we can be sure that promethazine is not the culprit but rather the problem from the laboratory but if this comes positive again, then you will have to discuss this with your doctor who can take you off promethazine and reschedule another test. Please note that, there is a very small amount of amphitamine in your system which occurs naturally and increased spikes of it can also influence test results. Hope this helps and wish you the best. Dr. Nsah
Above answer was peer-reviewed by
Follow-up: Does promethazine give false positive result during drug screening? 2 hours later
I neglected to tell you that I am also prescibed oxycodone. Does this change your conclusion. Tere are many postings to emedtv saying that many people have been given false positives with this cobination of meds. Tests show a positive for methaphamnes?
Answered by Dr. Nsah Bernard 5 hours later
Brief Answer: There is no reason it should show + Detailed Answer: Hello, Thanks for updating, I have come across several people levying the same complaints regarding false positive while on oxycodone but I have not read any scientific articles that show evidence of this. Oxycodone is a narcotic analgesic of the opioid class and most people will test easily for taking opiate but methamphetamine positive test should not normally exist if you are not a direct consumer of methamphetamine. I do believe how ever that, it is possible to test positive for amphetamine if you are not a user given that various panels exist for testing urine for common substance of abuse e.g. triage 8 that detects amphetamines, benzodiazepines, cocaine, methadone, opiate etc. The presence of any one of those drugs could read others false positive. So yes, it is possible to have a false positive test while on an opiate derivative. I suggest you get tested specifically for the presence of amphetamines in your system before any conclusions are drawn. Hope this helps further and wish you the best. Dr. Nsah
Above answer was peer-reviewed by
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