Feedback on False Positives from Drug Testing, page 136

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: Proair inhaler
Date: 5/26/2011
I went for a pre drug screening for employment and my test came back positive for cocaine. I have never used cocaine. Can proair make a false test?


AskDocWeb: Proair inhaler has not been reported to cause any false positives on urine drug tests. However, that doesn’t mean that your test result was a true positive. In order to find that out you would have to get a confirmation test.

Subj: Methyldopa false positive
Date: 5/27/2011
I have tested false positive for amphetamines while taking methyldopa this happened the other day. My situation is almost like the post from 1/11/2007. This is 5/27/2011. my children have not been taken away, however, I am under investigation. Each test was taken after I had my daily dose of methyldopa for my hypertension. It was d/ced and i took a swab test for the state, it was negative. I hope if this has happened to many other people, that they will report it so that the word can get out about this. Thank you.


AskDocWeb: Thanks C, we appreciate you sharing this. Now if we can just find a good source reference to document this it could be added to the list.

Subj: Ramipril bisoprolol and asprin
Date: 5/27/2011
I have just tested positive for THC and I am taking ramipril bisoprolol asprin for a heart condition. Can these tablets affect the test?


AskDocWeb: Sorry Pete, none of those are on
the list. As we have said before, if you suspect that your test resulted in a false positive or non-negative result, get a GC/MS confirmation test.

Subj: Stackers/ Dietary Supplements
Date: 5/28/2011
Can Stackers/ Dietary Supplements give you a postive on a urine test for cocaine, weed, or benzos?


AskDocWeb: As long as the Stackers supplement doesn’t have ephedra in it then it shouldn’t cause a problem.

Subj: Positive for amphetamines and benzos
Date: 5/29/2011
I am on bond and I have to take random drug screens. I am also on a suboxone program and take random drug screens. I recently took a test for bond and it came back clean, I went to my doctor and took another test approximately 4 1/2 hours later and it came back positive for amphetamines and benzos. I asked for another test to confirm this because I know that I hadn’t used either. I took 2 advil in between tests and I am diabetic and have liver damage. Will the confirmation test show that I am clean or do I have to worry?

I would also like to know how accurate the Icup tests are because I have tested positive for benzos one other time and I was clean then also. They use the same cups for both bond and at my doctor’s office. The only problem is on bond a false positive will place you in jail until the lab results come back. That seems unfair to me because I am not doing anything to mess up my bond. Please help so that I can show my PO that this does happen and they should at least wait until the lab confirms. Thank you very much.


AskDocWeb: The confirmation test is designed to rule out false positives so if you have been honest then you should be okay. According to the iCup ACCURACY DATA sheet published by Blue Grass Drug Screen, Inc. the test scores fairly high. Here are the numbers for the iCup test device:

  • 97% accurate for amphetamines
  • over 99% accurate for methamphetamines
  • 98% accurate for marijuana THC
  • 96% accurate for cocaine
  • 95% accurate for opiates
  • 98% accurate for PCP
  • 95% accurate for barbiturates
  • 96% accurate for benzodiazepines
  • over 99% accurate for methadone
  • over 99% accurate for tricyclic antidepressants (TCA)

Since the accuracy for amphetamines is 97% that may mean that 3 people out of every hundred have a problem.

In researching your answer we did run into one nasty little surprise. The Cross-Reaction data for the iCup says that Novocain may show up as a positive for opiates. Be careful about scheduling your dental appointments.

Subj: Testing negative for the methadone
Date: 5/31/2011
I take Metformin 1000mg tablets twice daily and lisinopril 20mg once daily as well as 60mg of methadaone hcl and 30 mg oxycodone as needed for pain my problem is that I constantly test negative for the methadone on my Doctors required UA’s and wanted to know if there is an interaction of medication causing this? Thank you for your help.


AskDocWeb: Testing negative for a drug that should be there seems to be a growing problem, especially at pain treatment centers. One possible explanation for this is that methadone can be reabsorbed in the urine as a result of alkaline urine. A patient who is on a relatively low (30 or 40 mg daily) may test negative for methadone simply because of a pH elevation into the alkaline range of 7.6 to 7.8, because of tubular re-absorption. [Source: Urine Drug Testing in family practice. UMDNJ-Center for Continuing and Outreach Education]
Another possibility exists because of the way methadone is metabolized by the liver. Individual patients may have genetic variants of liver enzymes (CYP450), or may be taking inducer or inhibitor drugs, that strongly influence opioid metabolism and, hence, their detectable presence or absence in urine (or blood, or oral fluid if used). For example, the unexpected absence of methadone upon testing can be due to rapid metabolism in a patient rather than therapeutic noncompliance or drug diversion. [Source: Carlozzi et al. 2008; Smith 2009]
Subj: Doxycycline Hyclate
Date: 5/31/2011
Can Doxycycline Hyclate cause a false positive on a drug test?


AskDocWeb: Depending on the method of testing, Doxycycline Hyclate may cause false urine glucose results but it is not known for causing false positives on urine drug tests.

Subj: PCP came back positive!
Date: 6/1/2011
I am on probation and I’m on a lot of controlled substances…one of the pills I took showed up positive in witch they should have (they are prescribed) but PCP came back positive! I don’t even know what PCP is. I have never done a drug in my life!!! I’m on Pristiq, could that throw off my UA results? I take: PRISTIQ TRAMADOL VICOPROFIN NAPROXEN ZANTAC KLONOPIN TYLENOL PHENHERIMINE BENADRYL


AskDocWeb: The only possibility of a false positive that we see is the Benadryl (Diphenhydramine). That has shown up as false positives for Benzodiazepines, PCP, and Tricyclic Antidepressants (References 24 and 45).

Subj: False reading for THC?
Date: 6/2/2011
can any of these drugs cause a false reading for thc if so which ones and what about diabetes opana er 15mg glyburide 5mg omeprazole 40mg pravostatin 10mg actos 30mg citalopram 40mg hydrochlorothiazide 25mg metformin 1000mg HCL Alprozolam .5 dozepin 25mg baclofen 10mg


AskDocWeb: The closest we could find to something on your list is Esomeprazole, which is the S-isomer of omeprazole. PPIs may test positive for THC (Reference 37).

Subj: Question?
Date: 6/3/2011
Great info!! I have a question but not sure where to post it??


AskDocWeb: Hi Tara, just go ahead and ask your question. If it is about false positives, this is a good place to post it.

Subj: False positive for amphetimines?
Date: 6/3/2011
Was given an urine test by po and I take Prozac 80 mg a day and wellbutrin 100mg 2 X day will these cause a false positive for amphetimines as I was told because I sure don’t use drugs.


AskDocWeb: There does seem to be a small chance of that happening however, a GC/MS confirmation test would eliminate them as false positives.

Subj: Failed a screening
Date: 6/3/2011
I recently failed a screening for methadone and benzos. I havent took neither of them. The only thing i have been taking is Atarax. I wouldnt care the charge just as long as doctors knew that this is REAL and happening.


AskDocWeb: The only way to find out if it is real or not is to get a confirmation test.

Subj: Hydromorphone
Date: 6/4/2011
I had to take a urine test with my doctor which was fine, because I have taken them before and they always came out with no problems. This time it did not and he will not see me anymore. I have a prescription for Oxycontin 20mg X 2 day, Oxycodone for breakthough 4 X a day, Vicoden 10/500 when needed. I was very sick with a terrible sinus infection and could not make it to the doctor to get my rx’s refilled. I had reduced the amount I was taking since I knew that I was going to run short.

I had taken dolcyline, antibiotic – and then Septra DS since the other antibiotic did not work. I also took some Advil sinus, and nyquil, a inhaler Pro-Air Albuterol that I had gotten from urgent care. I told them that I had been taking this and my test results came back as having Hydromorphone in it which was not listed on the approved drugs. Could the cold medicines, inhaler given a false reading?

I pulled up Hydromorphone to see what it was and was shocked to see dilaudid, as this stuff put in the hospital over 6 years ago because of adverse reactions. I have never abused my drugs and have no idea how this showed up in my test. I am beside myself…the number beside it was 641 which I have no idea what that means. Can you please help me out so I can try and get this straightened out. I keep all my drugs locked up in a safe due to teenagers in the house, I trust my son, but you never know about the others friends of his that are in the house. I also was taking vitamin B12, Vitamin D with C in it, and reservatrol, and I always take a low dose 81mg of aspirin a night. Sincerely,


AskDocWeb: The number 641 likely refers to the amount of drug found in the sample. The drug screen cut-off level for hydromorphone is typically 300 ng/ml, which is nanograms per milliliter. That means that your sample contained over twice the minimum detectable amount of Hydromorphone.

Vicodin contains hydrocodone which is metabolized by the liver and some of it breaks down into hydromorphone. Individuals with liver dysfunction may show higher concentrations of hydrocodone and its metabolites (hydromorphone).

Hydrocodone is usually combined with other medications for the treatment of pain or for cough suppression (Anexia, Allay, Bancap-HC, CoGesic, Dolacet, Hycodan, Hycotuss, Hycomine, Hydrocet, Hydromet, Lorcet, Lortab, Tussend, Tussionex, Hy-Phen, Maxidone, Norco, Panacet, Vicoprofen, Vi-Q-Tuss, and Zydone).

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