Questions about False Positives in Drug Testing, page 220

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.

Newborn infant positive for amp/meth
I just had my newborn infant taken from me for meth exposure. I have never used meth or any other drug. Baby urine positive for amp/meth, me negative. Merconuim sample sent for testing gc/Ms. It came back positive. 867 mnemonic/nl ? I was given iv drip during labor, magnesism solfate, oxcytocyn (to help labor restart). Could this have caused positive result? How do hospitals collect stool samples? What if stool mixed with urine? Help, I really don’t do drugs!!!


AskDocWeb: They do drug testing on the meconium because it shows everything that has crossed the placenta in the last 4-5 months of pregnancy. The first stool of the baby is collected in a sterile environment and the baby’s urine has no effect on the GC/MS test result. This test is usually only done if you meet the criteria such as limited prenatal care or something sketchy in your file. It is not a standard newborn test.

The word “mnemonic” refers to a learning technique that aids the memory in retaining information. It has nothing to do with drug testing.

Mouth swab
i tested positive for methadone and marijuana this is not possible because i havent used these drugs. but i DO take 36mg Concerta, night time sleep aid, aleve, and Ibuprofen and also use vicks nose spray. i got online and researched, i learned that most of these drugs will cause a false positive for meth/ marijuana. they took a mouth swab to dble check, will this swab test be able to show the truth?


AskDocWeb: The mouth swab is not a substitute for a GC/MS confirmation test. It is subject to many of the same causes of false positives that show up on urine tests.

Prochlorperazine (Compazine)
Took Prochlorperazine very early Sunday morning due to severe vomiting. Was mom’s Rx, now I’m kicking myself in the butt for not looking it up first. I just took a 10 panel drug screen for pre-employment today. Will this show up??? I am completely stressed. Thanks for your time.


AskDocWeb: Prochlorperazine is a prescription medication and taking anyone else’s prescription is illegal in most places. We do NOT support the illegal use of any substance.

Note for Debbie:Sending a private email from your current address prevents us from answering due to your Confidentiality Notice. Specifically: “If you are the intended recipient, any disclosure, copying, printing, or use of this information is strictly prohibited and possibly a violation of federal or state law and regulations.” In order to post to this forum use the form at the bottom of this page. You can make up a name if you want but the email address must valid.

Tested positive for cocaine
AskDocWeb: Methadone could have tested positive (for cocaine), it’s in the same class. Is this actually true? Does that mean that possibly suboxone could cause a false positive? My husband just tested postive for cocaine (and never used it) and lost his job at Exxon and is barred for three (3) years! He paid for his own hair folicle test at an independent lab and it came back negative for everything but they wouldn’t accept it. He’s never worked anywhere else (he’s always worked at the plants) but is barred from working at ANY PLANT for three (3) years! We need to know what could have caused it and what we can do to get his job back.


AskDocWeb: Sorry Terry, that statement was an error – and thanks for pointing it out so that we could correct it. It is our understanding that in order to invalidate the original test, the original sample must be subjected to a confirmation test with either GC/MS or LC/MS/MS. This is problematic because the original sample is typically kept for a limited amount of time and legal action may be required to force a confirmation test. Hair tests are not a substitute for confirmation testing because they produce too many false positive results. To date the only causes of false positives for cocaine that we have found are:

Antibiotics: Ampicillin and Amoxicillin

Buprivacaine (Marcain, Marcaine, Sensorcaine and Vivacaine)

Cola tea, cola leaf, cola flour, cola oil


Kidney disease

Tonic water

Tested positive for THC
I’m a US Marine and got told that I tested positive for thc today. I am very confused why, because I have not smoked marijuana in over 6 years. Through a little research, I discovered that Motrin, Aleve and Ibuprofen are among the large list of otc drugs that can cause a false positive test result. I believe that the gc/ms test was done, because the paper stated that it had 112 reading. I hear that the gc/ms test finds EXACTLY what is in your system but still do not see how I would test positive for something that I HAVE NOT INGESTED. Thank you.


AskDocWeb: First a couple of questions: Was the paper that stated the “112 reading” the actual GC/MS test result or just a notification of the results? Has your MRO confirmed the positive report from the lab?

Positive for cocaine
I recently had an injury at work and have to do a urine drug screen. The results came back positive for cocaine. I have been using a diet patch from off the internet that I recently quit using because it gave me the jitters. Plus I currently am prescribed estradial, zopidem, viibryd, flector patches, and take otc allergy medicine. Could any of these cause this result?


AskDocWeb: The medications you name are not known to cause a false positive on urine drug screens but the diet patch is an unknown. If you know the ingredients in it you can check them against this list of substances that are documented to have shown up as false positives.

Fentanyl patch
I am a pain patient. Went to the doctor yesterday & they did a urine test. I use the fentanyl patch & tested positive for a stimulant. The doctor asked me if I used meth. He said the patch could throw a false positive. They are sending it out for a more in depth test. I would never use that crap. I told them they I would give blood or what ever they need. I was so shocked. My 17 yr old son was with me. I do exactly what the doctor prescribes & that is all I use


AskDocWeb: We have only one reference for Fentanyl and that is from the book Principles of Addiction Medicine, which says that it may show up as LSD. Please let us know how your in depth test comes out.

Fentanyl patches and other prescription drugs
I am on disability due to 3 back surgeries. I am with a pain doctor & they did a urine drug screen. I tested positive for a stimulant & the doctor ask me if I used meth amphetimenes. Which no I have never used any illegal drugs in my life. This really bothered me. I am on the fentanyl patches along with other prescription drugs. They are sending it out for a more in depth screen. The doctor was aware that the patch could show a false positive. Have other people had this happen?


AskDocWeb: Yes, there are more than a dozen reports here about Fentanyl showing up on urine drug tests. Fortunately the additional testing of a confirmation test eliminates these false positives.

Positive for oxycodone
My boyfriend recently took a drug test for his work and it showed up positive for oxycodone. We knew he had been taking hydrodone and then lortab following an outpatient surgical procedure, so we knew that the test would show up positive for those, but the oxycodone was a surprise. He has NOT taken any and WOULD not due to the nature of his job and the random drug screens. Could either of these 2 drugs, or amoxicillin that he was prescribed, advil, tylenol, and aleve are also OTC drugs he took leading up to and following the procedure, have caused a false positive?


AskDocWeb: To date there are only a few medications that have been documented to sometimes test false positive for oxycodone. They are:

  • Hydrocodone (Reference: 41 and 57)
  • Hydromorphone (Dilaudid┬«) (References: 57
  • Oxymorphone (Numorphan) (References: 57
  • Suboxone (Buprenorphine) (Reference: 54)

In any case a confirmation test would show if he had a false positive test result or not.

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