Feedback on False Positives from Drug Testing, page 75

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: Failed a urine lab test
Date: 10/19/2009
I’ve failed a urine lab test for Marijuana from my P.O. and am fixing to go to jail. The test results were 73ng/mL over the 50,ng/mL. I haven’t smoked since 4/20/09. What would cause this? I believe it to be a false positive, because I passed the same drug screen the following week.


AskDocWeb: All the possible causes of false positives that we know of are listed here.

Subj: Hair follicle testing
Date: 10/20/2009
I had a false pos for cocain I haven’t used in over a year. To prove I didn’t I paid a lab for a hair follicle test, which came back neg for any use of any substance. Now my probation officer has me in a program. How accurate is the hair folicle test? Is it accurate enough to use in a court of law?


AskDocWeb: Hair follicle tests are accurate enough to be used in court. It is our understanding that in order for a hair follicle test to be used in a court of law, the samples used in drug testing must follow strict accountability or Chain of Custody rules. The chain of custody indicates the time, date, place and the name of the individual from whom the sample comes from and is updated and received by any person the specimen passes through. When received at the laboratory the safety seal is checked and if tampering is evident, it is discarded as an adulterated sample. The chain of custody sheet contains spaces for recording of the name of the individual who collected it, transported it and processed at the different authorized laboratories under the supervision SAMSHA and NIDA. Tampered safety seals are grounds for examination rejection most importantly if they are for application in Federal court cases or investigation.

Hair follicle testing can reveal drug use over the past 6 months, showing all of the toxins you used during that time. Some people try to get around this by shaving their head but that doesn’t work. If you do not have the required 1/2 inch on your head, they will go for the hair on your underarm, pubic, leg or arm.

Subj: Hair follicle drug test
Date: 10/20/2009
Recently, I moved to the country and learned what the world of allergies was all about. Over the past few week up until just last week I had been taken allegra for the allergies. I was also taking nyquil and robitussin cold and flu to fight off the flu that was going around our home. Last Thursday I found out I had to go that day and take a Hair Folicle Drug Test. The results came in on Monday showing I tested positive for methamphetamine at a quant. of 5,744 pg/mg and amphetamine at 553 pg/mg. Considering I do not do drugs, how could this have happened? Is it possible that the over-the-counter medications I have been taking could have affect or caused a false positive in the drug test?


AskDocWeb: Sorry Jennifer, all the data we have on false positives applies only to urine drug testing.

Subj: False positive?
Date: 10/20/2009
I recently took a drug test (urine), and I had a false positive for benzodiazepams. I take prozac and geodon. I had taken Klonopin 4 weeks prior to the test. Could one of my meds caused this or was the Klonopin still in my system?


AskDocWeb: Neither prozac nor geodon have been reported to show up as false positives. According to a Toxicology Lab Technical Brief from Dr. Joseph Graas, Klonopin contains benzodiazepines. The 2008 PDR says that Klonopin typically has a half-life of 30 to 40 hours. That is the amount of time it takes for your body to metabolize and eliminate one half of the drug. After the last dose, it takes about five and a half “half-lives” before the drug is completely out of your system. Depending on metabolism, that could be anywhere between 7 to 10 days.

Subj: Zoloft
Date: 10/21/2009
Please tell me if me taking Zoloft can cause a false positive, I have been taking a drug test(urine)and it keeps coming back as positive, I need an answer please!


AskDocWeb: According to Dr Robert Hsiung at the University of Chicago, Zoloft may show up as a false positive for benzodiazepines.

Subj: Over the counter meds?
Date: 10/20/2009
I am on numerous pain meds and was recently tested positive for heroin. What are all the over the counter meds that would cause this? I take bronkiaid for my asthma and have been fighting a very bad cold. Now my pain clinic is really giving me a hard time. I take ms contin for pain along with diluid for break threw pain.


AskDocWeb: There are several cough syrups listed here that may show up as heroin. Urine drugs tests have been reported to show Bronkaid as a false positive for Amphetamines, Heroin, Opiates, Ecstasy, and Meth (References 1, 3, 16, and 18). If your cold remedies contain dextromethorphan (DXM), that has also been reported to sometimes show up as heroin on urine drug tests. MS Contin Tablets contain morphine, which could also be a problem on some drug tests. With so many possibilities it is important to tell the people conducting the test everything that you are talking.

Subj: Diluted result
Date: 10/22/2009
I have been on probation for 4 years and had to take a UA about 3 weeks ago. It came back diluted which I had not heard of…my PO said I need to take another one on Monday and lay off caffeine etc. I drink about 10 cups of hot tea every day, take Ensure, mulit-vitamins. I do not take any drugs, short of some Advil, complex vitamins and fish oil. I need to go on Monday afternoon and what can I do to not have a diluted result again. Many thanks.


AskDocWeb: Drinking too much liquid, that includes your hot tea and any other liquids, can lead to a diluted result.

Subj: Tested positive for bezodiazepine
Date: 10/23/2009
Hi! I tested positive for bezodiazepine a while back! I’ve been trying to understand why and was wondering if the following would be the reason: metronidazole 500mg, sulfameth/trimethoprim 800mg, or ibprofen 800mg, these were the only meds I could think of over the past several months.


AskDocWeb: None of those have been reported to cause a false positive for benzodiazepines although Ibuprofen sometimes show up on urine drug tests as a false positive for Marijuana (THC).

Subj: Problems with drug testing
Date: 10/23/2009
I am having problems with drug testing results for PCP and amphetamine. The Vyvanse is the reason for the amphetamine, (but could be a factor for PCP if combined with the other combinations of prescribed medicines for bipolar/ADHA/depression, anxiety and asthma. I am on: Pristiq (sister of Effexor), Focalin, Vyvanse, alprazolam for panic attacks, Lamictal, Provental inhaler for asthma, I take ibuprofen often for headaches and Trazedone for sleep. I’ve read that a few of these can cause false positives for PCP, maybe even more if it a combo of these meds. I am in a precarious situation, and I am not using anything I’m not supposed to be or that is necessary for me. The lab said I tested positive for the more extensive test (urine) freeform at their lab. Can you please help me, it is court related, and I’m very concerned. If you can explain it, or give me some type of scientific explanation if a combo causes this, I’d appreciate it very much, please help!


AskDocWeb: Sorry Cheryl, we can’t speculate on the combinations of drugs. You need to ask your lawyer to be sure but it is our understanding that urine tests can’t be used as proof of drug abuse in a court of law because they are not accurate enough. They produce too many false positives. What can be used is the GC/MS confirmation test. That’s a Gas Chromatography/Mass Spectrometry test that will eliminate false positives.

Update 6/30/2011: A hospital in Florida has reported that lamotrigine (Lamictal®) has shown up as a false positive for Phencyclidine (PCP) on rapid urine toxicology screens.

Subj: Urine testing
Date: 10/24/2009
Will drugs like klonipine show up in my urine if I add a pill of klonopine to my urine because they say they are negative results. Thanks,


AskDocWeb: No, that would just make it appear that you are overdosing on the drug, which is another kind of abuse.

Subj: Lobelia Extract Resin (Lobeline)?
Date: 10/24/2009
Hi, I’m great need to know if Lobelia Extract Resin (Lobeline) can cause a false positive and/or cause me to fail a drug test.


AskDocWeb: There are no reports about Lobelia Extract Resin causing any problems with urine drug testing.

Subj: Amoxicillin
Date: 10/26/2009
Can Amoxicillin give a false cocaine dirty for u/a or blood screen?


AskDocWeb: We found several sources that say Amoxicillin may show up as a false positive for cocaine (References 13, 16, 18, 20, 21, 26, and 29).

Subj: Tested positive for cocaine
Date: 10/26/2009
I tested positive for cocaine in a urine test. I have not used cocaine. The sent my urine to a lab for a test, they say it was positive for cocaine. Not sure what kind of test, probation did not know either. I had a complete blood panel done and found my Lympohcytes are high. Can these cause a false positive for cocaine?


AskDocWeb: A lymphocyte is a type of white blood cell that responds to infection. They are part of your immune system but they are NOT known to cause a false positive for cocaine. There are three types of lymphocytes, T cells, B cells, and natural killer (NK) cells. Each type acts in its own way to eliminate specific pathogens (infectious agent) or cells infected by pathogens.

Subj: Tested positive for meth and THC and alcohol
Date: 10/26/2009
My mom is taking court ordered drug tests, she recently tested positive for meth and THC and alcohol. She has had a drug problem but has been clean for 26 days. She has never drank. Could these results be altered by food?


AskDocWeb: Sorry Renee, there is no food that would produce results like that on a drug test.

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