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False Positives
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False Positives

Someone the other day was talking about failing a drug test for opiates and claimed to be clean...I was doing a homework assignment and ran across this article..........

Medications & Substances Causing False Positives

According to a report by the Los Angeles Times News Service, a study of 161 prescription and over-the-counter medications showed that 65 of them produced false positive results in the most widely administered urine test. Ronald Siegel, a psychopharmacologist at UCLA said "The widespread testing and reliance on tell-tale traces of drugs in the urine is simply a panic reaction invoked because the normal techniques for controlling drug use haven't worked very well. The next epidemic will be testing abuse."

Byrd Labs has in its possession an internal document from the Syva Company, makers of the widely used EMIT test. This document, leaked by a disillusioned company employee, lists more than 250 over-the-counter medications and prescription drugs that can cause false positives (this is only a partial listing.


*Pain relievers such as Advil, Nuprin, Motrin and menstrual cramp medications like Midol and Trendar. All drugs containing the widely used pain reliever Ibuprofen, are known to cause positive samples for Marijuana. Non-steroidal anti-inflamatories such as Naproxyn have cross reacted in blind tests. These are often prescribed for runners, sports injuries to joints, and those suffering from arthritis.

Syva labs has recently reworked its Cannabanoid test and claims to have eliminated this problem. But a Science Magazine article (July 8, 1988) lists Ibuprofen as cross reactive. Under the new government guidelines THC testing levels will be reduced to 50 nanograms. Many more THC false positives can be expected in 1994.

*Dristan Nasal Spray, Neosynephrine, Vicks Nasal Spray, Sudafed, etc. and others containing ephedrine or phenylpropanolamine. Over-the-counter appetite suppressants which contain propanol amine. Most common nasal decongestants can cause a positive reading for amphetamines; amphetamine false positives are the most common. Recent articles in the Journal of Clinical Chemistry, Vol. 38, No. 12, 1992 and Vol 39, No. 3, 1993 warn that medications containing chlorpromazine, fluspirilene, and others may yield a positive when tested for amphetamines.

*Vicks Formula 44M containing Dextromethorphan, and Primatene-M containing pyrilamine as well as the pain reliever Demerol, and prescription anti-depressant Elavil test positive for opiates up to three days. Even Quinine water can also cause a positive reading for opiates.

*Poppy seeds such as on the Burger King roll, on a bagel from your favorite deli, etc. The Journal of Clinical Chemistry, Vol. 33, No. 6, 1987 reports: "The quantities of poppy seed ingested in this study represent this study (25 and 40 g) may be expected to be contained in one or two servings of poppy seed cake.

Therefore, poppy seeds represent a potentially serious source of falsely positive results in testing opiate abuse." Clinical Chemistry goes on to conclude: Not only is it difficult to distinguish heroin or morphine abuse from codeine, but dietary poppy seeds can give a strong positive result for urinary opiates for several days duration that is confirmed by GC/MS analysis."

*Nyquil Nighttime Cold Medicine will test positive for Methadone up to two days.

Antibiotics. Certain newly developed antibiotics have caused positive sample urine tests. Ampicillin is suspect. Amoxicillin has caused positives for cocaine.

*Diazepam tests positive for PCP as well as the ingredient in some cough medicines, Dextromethorophan.

*Your own enzymes. A small fraction of the population excrete large amounts of certain enzymes in their urine which can produce a positive drug test. Dr. John Morgan of the Dept. Of Pharmacology of New York City University writes: "A false positive test could occur in some individuals because they excrete unusually large amounts of endogenous lysozyme or malate dehydrogenase." Dr. Morgan judges that natural enzyme interference may run as high as 10% of positive samples.

*Black Skin. (This is not a joke!) Those of African origin, certain Orientals, or Pacific Islanders might test positive for marijuana. Dr. James Woodford, a toxicologist associated with Emory University labs hypothesized the pigment melanin which protects the skin from the sun approximates the molecular structure of the THC metabolite to cross react on the marijuana urine test. Dark-skinned Caucasians such as those from the sub-continent of India could also read positive on marijuana tests. The body eliminates some melanin in a dark person's urine sample.

*Passive marijuana inhalation. If you attend a rock concert or ride in a car where marijuana is smoked nearby, even if you do not partake, the second hand marijuana that you might inhale can give your test a positive result for several days.

Web sites for more information on urine testing, false positives, etc.

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5 Comments Post a Comment
Very interesting information.  We own a business in which our employees are required by our clients to be drug tested prior to some jobs.  I will forward this to my husband.  Thanks.

I remember a Seinfeld episode where Elaine had tested positive for opiates and they figured out it was the poppy seed bagels she ate every morning on her way to work.  It was a pretty funny episode.

I know we both tested positive for like almost three months after joining the clinics. Since I don't recall popping pills or injecting drugs during that time (think I'd remember!),
I concluded that the clinics here in NY automatically mark you down for positive to opiates in tests in the beginning of "treatment". Why, I don't know. I could guess, but why bother?
I wonder what the sensitivity of the OTC test kits are. (mouth swab), if they're any better.
I was recently drug tested ( urinalysis) it didnt come back for 7 days. Then i was told i was positive for cocaine use. Havent used it and never would. I did some research and found that Kidney Infections can cause a false negative. Is this accurate? I am also on the following other medications, Relpax, Promethazine, Topamax, Norco, Nexium, Celexa, Alprazolam, Synthroid, Fexeril and Norflex. I was tested on a Tuesday and couldnt get in to see the doctor on Thursday, where i was diagnosised with Kidney infection and two other meds Cipro and Pyrdium. I starting urinating blood the day before. Is there any light for me at the end of this tunnell? The company is scheduled to term. my employment tomorrow.

Please help!


The best place for answers like this is to Google it.
This is really interesting and good infor. ro some posters. I know sm 1 was inquiring about a false pos. test the other day, so I came across this and thought I would bring it up again! Hope it helps that person if still posting.
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