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Dr. Andrew Rynne
Dr. Andrew Rynne

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What causes false positive result for metamphetamine while on Promethazine?

Answered by
Dr. Michelle Gibson James

General & Family Physician

Practicing since :2001

Answered : 16766 Questions

Posted on Mon, 22 Aug 2016 in Brain and Spine
Question: I got strep and have the promethazine and zithromax meds plus my welbutrin and I tested positive for amphetamines and methamphetamine and I haven't used any meth truly a long while and now I'm looking at a bad situation and I need to figure this out by Monday or I go to jail for something I worked hard to stop

The Amphetamines and methamphetamines coming up positive was disputed by me of course and requested to send to a lab I tested yesterday around 445pm-530pm and was notified at 3pm today not even 24hrs later that I came up positive for methamphetamine and terminated from the outpatient treatment program and now because I was late and missed my first few classes due to work purposes, I was placed on contract and the counselor said I never notified about prescription medicines and I made sure to go through my intake packet and she brushed through saying see it says prescribed medicine taken as needed orally and no list of what or the mg or anything but her arm was covering the list because I had mentioned it and than 20/25 min later preparing my test when the cups are in bathroom the male counselor was back there and all day i could of tested in and out immediately til i said that I wont test til i see the initial paperwork and show you and that was advice from my P.O and caught the counselor lies now I'm dirty and terminated so now I go to jail like I need help on this I got two kids and a wife
Answered by Dr. Michelle Gibson James 3 hours later
Brief Answer:
promethazine can cause false positive for amphetamine and metamphetamine

Detailed Answer:
HI, thanks for using healthcare magic

Some medications can cause false positive results. Promethazine is one of the medications that can cause false positive results for amphetamines and metamphetamines so this could have contributed to your result

There are more specific tests that can pick up if you are truly or falsely positive. The specific test- GC-MS is used to confirm or deny blood tests.

Your doctor/counselor or yourself can consider doing this more accurate test.

I hope this helps,feel free to ask any other questions
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
Follow up: Dr. Michelle Gibson James 2 days later
so i got off the phone with the program chief director and she stated that they're program was voted one of the most strict and best outpatient program there is. I wanted to say that because she followed stating they use top of the line Lab Test coming from UCI XXXXXXX Now she went into chemical compounds and breakdowns and so on , But , I myself would have to say science was my favorite subject and still is , SO , No matter how good the lab they use to test the specimen or how popular if i am not mistaken the lab test must chemically perform #3 different specific Tests in order to correctly test and break the Amphetamines and Methamphetamine down to identify what it actually came from and the percentage as well as if the test was simply just dirty? For example , Was it a Prescription medicine or a illicit street drug causing the positive test and had i been using Methamphetamine , Please correct me if im wrong but i believe the test wouldn't come back with Amphetamines as well.
One more question is that i was also informed and researched that Syraquil , Norco , Zithromax , and Promethazine in combination will ason easily result in a positive test for Amphetamines as well as Meth
Answered by Dr. Michelle Gibson James 7 hours later
Brief Answer:
bupropion can also contribute to result

Detailed Answer:

Sorry about the late reply

The initial drug tests is normally a screening test to look specifically for certain chemicals, in this case amphetamphines and metamphetamines.

Metamphetamine is a member of the phenethylamine family of medication, amphetamine is also in this family of medication. Amphetamine is a breakdown product of meth.

Since metamphetamine breaks down to amphetamine, it is sometimes possible to pick up both because they are in the same family and the meth breaks down to form the amphetamine.

As mentioned earlier, the promethazine can cause a false reaction/result.
The welbutrin can also contribute as well

Norco is a combination of acetaminophen and hydrocodone. It would be more likely to cause a false positive for opiates (since hydrocodone in this family of medication)
zitromycin and seroquel are not known to cause this false positive reaction

Please feel free to ask anything else
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
Follow up: Dr. Michelle Gibson James 3 days later
So i want to thank you very much for the answers that you have provided me in this manner as everyone seems to avoid the percentage amounts of the ( MAMP) that shows if it is being used as a illegal street drug or if it is part of the same chemical family and , In my opinion these medications have certainly caused a false-positive test not to mention i am still being accused of the use of Meth when , Please correct me if i am wrong but to determine what the actual breakdown is on a false -positive test is a very difficult and expensive process and contains the specialties of #3 Specific Laboratory testing procedures that would probably be heavy on the pocket and also would certainly take more than 24-72 hrs to obtain results. I also believe they need to have a facility that will offer that specific procedure and according to what I have personally learned these accusations should not be said in the unprofessional manner of " Yeah so i am regarding your results and its dirty for Meth " well whats the percentage of what chemical was found to determine the test was Positive for illegal Methamphetamine use ? I also wonder why Nobody has mentioned anything about the Amphetamines and that percentage that was found and is a result from what? since they can break it down and tell exactly what it is?
ONE more crucial question i have for you doctor is the the simple fact that the Amphetamines showed up as well as the Methamphetamine, Typically if one were to utilize the street drug Methamphetamine, I dont ever recall the test coming back with the Amphetamines coming up as well from using the illegal Methamphetamine street drug

i believe i have stated the Medicine incorrect if not please correct me, I did find that Quetiapine (Seroquel) does have the possibilities to have a false positive for Amphetamines , I did find that 1% of 10,549 people which equals 105.49 people do have Urine Amphetamine positive drug screens. The age bracket 100% in the 20-29 years of age that have these false positive test results. The Top Co-Used Drugs for these people are *Trimox *Ibuprofuen *Amoxicillion and i just wanted your Medical opinion on this Dr XXXXXXX Gibson XXXXXXX Thank You for your time and efforet in answering my questions and concers.
Answered by Dr. Michelle Gibson James 19 hours later
Brief Answer:
due to structural similarity

Detailed Answer:

Again sorry about the delay

Because of the similarity between these two agents, the metamphetamines and the amphetamine, where ever the origin, a cross reaction can occur. It may not occur in each case but it is always a possibility.

There are a number of meds that can potentially cause a false positive reaction. These 2 are not typically listed.

There is a comprehensive list available in a medical article on page 4 of the following article by KE MOELLER- called urine drug screening, a practical guide for clinicians
It lists over 20 possible meds.

As mentioned before, 2 of your meds- promethazine and welbutrin, can cause false positives

If anything else unclear, can let me know
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar

The User accepted the expert's answer

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