Feedback on False Positives from Drug Testing, page 35

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 we do not give medical or legal advice.

Subj: Prescription medications
Date: 3/8/2008
My son, who is on probation, tested positive for marijuana. He is on multiple prescription medications for asthma, sinus, allergies. A list of some of the medications are: fexofenadine hcl, ibuprofen, benzonatate, singular, tussionex, albuterol, singulair, clonepin, brovex, recent breathing treatment for asthma, advair. Can this cause a false positive?

AskDocWeb: False positives do happen in a small percentage of cases but yes, it is possible. Here is our current list of reported causes for a false positive for marijuana.

  • Advil (Ref: 1, 14, 16, 18, 20, 26, 29) (Ref. 22 says NO)
  • Aleve (Ref: 1, 3, 16, 18, 21)
  • Anaprox (Ref: 1, 3, 18
  • Ansaid (Ref: 3)
  • Apo-Naproxen (Ref: 1)
  • B2 vitamin (Ref: 21)
  • Bayer Select Pain Relief Formula (Ref: 3, 18)
  • Clinoril (Ref: 3, 18)
  • Cramp End Tablets (Ref: 3, 18)
  • Diabetes (Ref: 3, 15, 16, 20, 21)
  • Dolobid (Ref: 3, 18)
  • Dronabinol (Ref: 16, 18)
  • Edecrin (Ref: 3, 18)
  • Efavirenz (Ref: 32)
  • Excedrin IB (Ref: 3, 16, 18)
  • Feldene (Ref: 3, 18)
  • Fenoprofin (Ref: 1, 7)
  • Flurbiprofen (Ref: 3)
  • Genpril (Ref: 3, 18)
  • Haltran (Ref: 3, 18)
  • Hempseed Oil (Ref: 3, 16, 21, 29)
  • Ibuprin (Ref: 3)
  • Ibuprofen (THC) (Ref: 1, 3, 16, 18, 29) (Ref. 22 says NO)
  • Ifenoprofen (Ref: 3, 13, 18, 21, 26)
  • Indocin (Ref: 3, 18)
  • Ketoprofen (Ref: 3, 16, 18)
  • Kidney infection (Ref: 3, 15, 16, 21)
  • Liver Disease (Ref: 3, 15, 16, 20, 21)
  • Lodine (Ref: 3, 18, 20)
  • Marinol(Ref: 3, 16, 18)
  • Meclomen (Ref: 3, 18)
  • Medipren (Ref: 3, 18)
  • Mediprim (Ref: 3)
  • Midol (Ref: 3, 18, 26, 29)
  • Motrin (Ref: 1, 3, 16, 18, 20, 26, 29)
  • Nalfon (Ref: 1, 3, 7, 18)
  • Naprosyn (Ref: 1, 3, 18)
  • Naproxen (Ref: 1, 3, 16, 21)
  • Navonaprox (Ref: 1)
  • NSAIDS (Ref: 3, 18, 20, 32) (Ref. 22 says NO)
  • Nuprin (Ref: 3, 16, 18, 20, 26, 29)
  • Orudis KT (Ref: 3, 16, 18)
  • Oxaprozin (Ref: 3, 18, 34)
  • Pamprin® (Ref: 3, 18, 20)
  • Phenergan® (Ref: 3, 16, 18)
  • Promethazine (Ref: 3, 16, 18)
  • Promethegan (Ref: 3, 16, 18)
  • Relafen (Ref: 3)
  • Riboflavin (Ref: 3, 16, 18, 21)
  • Rufin (Ref: 1, 3)
  • Shampoo containing hemp (Ref: 29)
  • Tanning lotion containing hemp (Ref: 2)
  • Tolectin® (Ref: 3, 18, 20)
  • Trendar Cramp Relief Formula (Ref: 3, 18, 26, 29)
  • Vitamin B2 (Ref: 3, 16, 18)
  • Voltaren (Ref: 3, 18)

“Ref:” stands for references and can be checked on this page.

Subj: Diazepam?
Date: 3/8/2008
False positives on immunoassay tests are rare, but can happen. To make the claim that Diazepam tests positive for PCP implies that it definitively does, every time; far from the truth. Site some reputable scientific case studies. Your claim on this matter is erroneous, verging towards irresponsibility. How much have you researched the Diazepam PCP correlation? I would be interested in garnering a reply from you, but doughty I will get one. RGDS Diazepam,


AskDocWeb: Of the hundreds of drugs on our list readers may wonder why you complain about only one. Do you by chance work for the drug company that makes it? In any case the report that diazepam can test positive for PCP comes from an internal document from the Syva Company, makers of the widely used EMIT test. That document, leaked by a disillusioned company employee lists many medications that can cause false positives. Of course that is not proof but it is an indication of a possible solution for innocent people who are accused of using PCP. A GC/MS confirmation test will show the truth.

Subj: Cymbalta
Date: 3/12/2008
Can Cymbalta cause a false positive for Meth?; I already know the Nyquil will.


AskDocWeb: There have been no reports of false positive problems with Cymbalta.

Subj: Urine test came back positive
Date: 3/12/2008
My son was tested at his University for marijuana use. This was a urine test and it came back positive at what they say was a high level for amphetemines. In researching I read that a urine test cannot determine levels just the existence of the drug. Can you provide some insight? He faces suspension from school as of 3/12/08. Also is a test valid that is not done in a controlled environment? I believe the testing is being done in the pharmacy school and not a lab.


AskDocWeb: There are many different urine tests and without knowing the name of the test they used it is not possible comment on that. If you have any doubt about their testing, ask to see the results of the GC/MS confirmation test. You can also request a copy their certification to perform drug testing.

Subj: Herbal substances
Date: 3/12/2008
I would like to know what kind of herbal substances could cause a false positive for marijuana. I make my own herbal extract out of echinacea, chaparral, yellow dock, garlic, sarsparilla, sassafras, ginseng, ginger, licorice, and poke root. Would any of these cause a false positive, or could you direct me to someone who would know? Any info is greatly appreciated.


AskDocWeb: None of the herbs you list are known to cause a false positive. However, there are health concerns with echinacea, licorice, garlic, and ginseng.

Subj: Tested positive for cocaine
Date: 3/12/2008
Tested positive for cocaine on a drug test at my job. Have never done cocaine in my life. I am on Aviza for chronic pain and I was taking Amoxicillin and another pain medication at the time of the test(I don’t have the name of it on hand). Could any of these cause a false positive reading? Please respond. Thanks.


AskDocWeb: In a small percentages of cases Amoxicillin has been reported to cause a false positive for cocaine (Reference numbers 13, 16, 18, 20, 21, 26, and 29).

Subj: Excuse for failing the test
Date: 3/13/2008
I have been smoking pot for the last month, I have stopped for the last four days. I have to take a hair follicle drug test and would like to know how I will be able to pass it or if there is something that will cause a test show positive. I need an excuse for failing the test.


AskDocWeb: Sorry, this forum is for innocent people accused of drug abuse.

Subj: Trocaine and decorel forte
Date: 3/15/2008
My son is currently in drug rehab. They have given him the following over the counter medications (trocaine and decorel forte). He failed a methadone test. Could any of these drugs cause a positive test for methadone?


AskDocWeb: Neither have been reported to cause false positives.

Subj: False positive for benzos?
Date: 3/18/2008
I work in treatment center and I have had three clients test positive for benzodiazepines on a 5 panel test card. We sent all 3 to the lab and they came back negative. The one thing they have in common is they all take prozac. Can prozac give you a false positive for benzos?


AskDocWeb: It would be helpful to know the name of the manufacturer of your 5 panel test card. You might check the website of the manufacturer and the distributor but prozac has not been reported to cause false positives.

Subj: Promethazine/codeine cough syrup
Date: 3/19/2008
My wife has had to take repeated ua tests for the past few months for a DUI charge that we are in the process of arguing. She takes many medications for depression, anxiety, and ADHD. Her behavior and nothing else was the reason for her arrest. We have given the courts all records of her medications while undergoing the UA testing and just recently one has come back positive for cocaine metabolite. The only medication change in the two months of this was a prescribed two bottles of promethazine/codeine cough syrup, which they had a record of. I saw here on this site it was mentioned this can cause a false positive. Since this is the only site I have seen this information, where can I get the definitive answer I need to go before the judge. Also if we request the GC/MS test I’ve heard described as so accurate, will this test differentiate between this cough syrup and cocaine? The probation dept. already has told us that there is no way it could be anything other than cocaine. Where do I start?


AskDocWeb: A good place to start is with the GC/MS test which will differentiate between cough syrup and cocaine. Please note that the only false positive that has been reported to occur with promethazine in drug screening was for THC. See references 3, 16, and 18.

Subj: Lyrica
Date: 3/21/2008
Lyrica made me test positive for THC…the drug company sent me post marketing studies with numerous false positves reported. Has this happened to anyone else?


Subj: Nexium?
Date: 3/22/2008
I am a criminal defense attorney and I have a client who was a chronic marijuana user for an extended period of time. He has been on probation for approximately one year, and has tested negative for any drug use each and every month. Recently, he tested positive for THC, despite his claim that he has not smoked or ingested marijuana since being placed on probation over one year ago. He was prescribed Nexium immediately prior to the positive drug screen, and feels that it may have been responsible for same. In an earlier post, I read that an individual asked if Nexium could cause a false positive for THC, to which the answer was something along the lines of “it could, but it is not likely.” Can you provide any further information regarding a possible false positive caused by Nexium? I know that Nexium is in the same class of drugs as Protonix, which has been shown to cause false positives for THC. This young man is looking at serving a lengthy jail sentence, and I have been unable to find any further information to support his claim that Nexium may have caused this false positive for THC. Any information you may provide would be most appreciated. Thank you.


AskDocWeb: We say there may be a possibility but only because it is in the same class as Protonix. There are no references listed about Nexium although you might try contacting the manufacturer that makes the drug screening test.

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