Feedback on False Positives from Drug Testing, page 63

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: Positive for oxazepam?
Date: 5/1/2009
I recently had a UA come back positive for oxazepam and I don’t know why or what that is. I take ambien, promethazine, omeriprazole nd acai berry supplements would any of these show as oxazepam?


AskDocWeb: None of those show up in our database for giving a false positive for oxazepam but if you get a GC/MS confirmation test, that should clear up any false positives.

Subj: Hydrocodone
Date: 5/2/2009
How much hydrocodone will cause you to fail a hair drug test? I only took two 500mg pills about a month ago for back pain. I got them from my mom they where not prescribed. At work they took a hair sample for a drug test. Like I said I only took two. Will that cause me to fail my drug test? I didn’t like the way it made me feel so I didn’t take anymore.


AskDocWeb: Using drugs that belong to someone else is against the law. This section is here to help those who are innocent of drug abuse.

Subj: Salvilotus Salvia
Date: 5/2/2009
If u smoke Salvilotus Salvia and (Egyptian Blue Lotus) can it come up as a false positive and make you fail the drug test?


AskDocWeb: Sorry Elias, we have no information on Salvilotus Salvia.

Subj: Tramadol
Date: 5/2/2009
Would tramadol cause a drug test to show positive as a barbituate?


AskDocWeb: No, tramadol is not a barbiturate.

Subj: Cross reactive to barbiturate?
Date: 5/5/2009
Want to know the name of the drugs which are cross reactive to barbiturate on urine drug screening.

dr Tejas

AskDocWeb: Sorry, if you want to be a toxicologist you have to do your own homework.

Subj: Keflex?
Date: 5/5/2009
I take keflex 500 MG 40 of them can that make a false positive for cocane I tested positive but never did it and when they send out for the levels will that show any diffrence between the 2 thanks,


AskDocWeb: There are no reports about Keflex causing false positives. If they send your sample out to a certified lab for a GC-MS confirmation test, that should identify any false positives.

Subj: Foods that can create false positives
Date: 5/5/2009
My wife was just released onto parole. We were informed that there are certain foods or ingredients in foods that can create false positives. If this is true would you be so kind as to list them or direct us to where we can find the list in order to avoid any problems? Many thanks and may god bless you and yours.


AskDocWeb: We are compiling a master list of all the substances that have been reported to show up as a false positive on urine drug tests. Here is the list. While most of these are prescription drugs there are some herbs and drinks of which you should be aware.

Subj: Hair sample and tested positive
Date: 5/6/2009
I recently had a hair sample and tested positive for codine. Never done codine in my life. Here are the follwing medicines I have taken tylenol, extra strenth tylenol, tylneol cold and flu pill and liquid form claritn sudafed, robitussin cold and flu night quil, day quil and thats it in the last 6 months. Can that cause a false positive?


AskDocWeb: Sorry, the data we have only applies to urine drug testing.

Subj: Chlorpromazine or depakote?
Date: 5/6/2009
Can chlorpromazine or depakote give fales postive on a swob test, for methodon and ampetamine. Please,


AskDocWeb: There are reports of false positives with chlorpromazine but those were on urine tests, not swab tests. Depakote has not been reported to show any false positives on urine tests.

Subj: Blood test was positive for opiates
Date: 5/7/2009
I have reviewed you web site and it states that Tylenol 3 – can cause positive for opiates (Ref: 20) Tylenol 4 – can cause positive for opiates (Ref: 20) Is Tylenol AM one of the over the counter medications that can cause a false positive for opiates. I have a client that was in a car accident and had a blood test shortly after the accident. The blood test was positive for opiates. He claims that he did not use heroin before the accident. However, he took tylenol AM. If Tylenol AM does give a false positive for opiates is there a scholarly source you can point me to that would report on false positives caused by Tylenol products.


AskDocWeb: Sorry Anthony, the information here only applies to urine drug testing, not blood tests.

Subj: Pregnancy test
Date: 5/6/2009
I am 6 days late for my period. I took 7 home pregnancy test 3 of them showed positive and the others are negative and the health department which I took Monday showed negative. I have been taking oxycodene for pain would this med be related to me missing my peroid of having false negatives or positive on a pregnancy test? The only sign of pregnancy that I’m having is morning sickness even then I’m not really feeling pregnant. Help me please!!


AskDocWeb: There are several things that can contribute to a false positive or false negative pregnancy test. Some medications can affect the test results but oxycodone is not one of them. Even the timing of the test can affect the results. To get the most accurate test results:

  • Take the test in the morning because your hCG pregnancy hormone level is at it’s highest.
  • Take the test no more than 1 or 2 days before expected period. Although some tests say that you can see results up to 5 days before your missed period, the percentage of accuracy is very low.
  • Avoid drinking a lot of fluid before taking the test because it will dilute your urine and can affect the results.
  • Urinate for as long as possible on the strip.
  • Wait for the results. It is important to read the results within the amount of time given in the instructions for the particular pregnancy test that you bought.

A false positive is very rare but is possible if you took the test during menstruation and blood came in contact with the test strip or you experienced a chemical pregnancy.

Subj: Combination of drugs
Date: 5/8/2009
Could the combination of the following drugs cause a false positive for cocaine: Cyclobenzaprine, hydrocodone, oxycodone, Flexeril, Skelaxin and Percocet.


AskDocWeb: That is a bad combination of drug if you have to take a drug test. Hydrocodone Bitartrate contains synthetic opiates and oxycodone is a simisynthetic pure opioid. Percocet is a combination of oxycodone and acetaminophen.

Subj: Effexor and Neurontin?
Date: 5/10/2009
My friend is diabetic and takes Effexor and Neurontin she is not using drugs but keeps coming up positive for opiates on her drug screen. Can either of these drugs cause a false positive for opiates? She is on probation and is about to be sent to jail for something she is not doing.


AskDocWeb: Neurontin is not on the list but Effexor Tablets (venlafaxine hydrochloride) have been reported to cause problems on urine drug tests. Those problems involved false positives for PCP but if she isn’t taking anything else then that may be something to consider. Getting a GC/MS confirmation test may keep her out of jail.

Subj: Ibuprofen and Zicam
Date: 5/11/2009
I jus got out of jail a week ago and used ibuprofen while I was in there and I wanted to know how long it would stay, and also I took some Zicam cold remedy and was wondering if you know anything bout that thanx,


AskDocWeb: The half-life of Ibuprofen is only a couple of hours but it may take up to 24 hours to completely exit your system. Zicam has not shown up in any of the reports for false positives.

Subj: Tested positive for meth
Date: 5/14/2009
I recently blacked out, black out and fell into my shower/tub and I’ve had 3 back surgeries, have mild nerve damage and a lot of scar tissue. I do have a pain management Dr. He has me taking paxil 20mg 1 at bedtime, zanaflex 4mg & 2 mg 3 times a day, sonata 10mg 1 at bedtime, lyrica 50mg 3 times a day, norco10/325mg 1 every 4 to 6 hours, and I take benadryl for allergies. I went to the ER after I blacked out told them everything going on they did blood test and urine test later telling me I tested positive for meth, which I have never used. What do you think caused this? Help.


AskDocWeb: Sorry Jennifer, nothing you list has been reported to cause a false positive for meth.

Subj: Tested positive for cocaine
Date: 5/14/2009
I recently went to pain management where they urine tested me. I am presently taking Endocet 10/650 and Fentanyl 50 patches, along with Hydorcodone 7.5/750. I had ran out of patches a week earlier and a friend of mine gave me some Fentora 800 buccal tablets to help with the Fentanyl withdrawl symptoms until I saw my doctor for my monthly supply. A couple of patches had torn off when drying off after my showers and that is how I ran low on the patches. I wasn’t expecting to get sent to pain management to get my scripts but when they pissed me, they said that a faint line had come up under cocaine. God as my witness, I HAVE NEVER TOUCHED COCAINE A DAY IN MY LIFE! He then said that I had showed up positive for something else but wasn’t going to tell me. Then he said that he would cut my scripts but if my urinalysis came back dirty that he would never treat me again. Then he called my doctor and saw that I was 4 days early for my meds and made me wait for the urinalysis to come back. It has been two weeks now and they let me know that my results are back but that they can’t give me my results until I follow-up with the pain doctor.

I now have to drop another $30 cash co-pay just to be told God knows what. Does this sound right to you? How could something show up in my system that was never put there? Do any of the drugs that I am on cause any false positives for cocaine? I bought a 12-screen drug test in the pharmacy for $40 and only tested positive for “OXY” and “OPIATES.” but NEGATIVE FOR COCAINE and everything else!! Do you think that they would have me come back to drop another $30 if they were going to tell me that they can’t help me? I just don’t understand how I tested positive for cocaine on their test and not on the over the counter one. How does Fentora show up in the urine? The doctor said that I tested negative for Fentanyl. Is there even a test for Fentanyl? Please help me figure out this mystery because I have been totally devastated and feel like an innocent person convicted of a crime that they didn’t commit. I just want my life back!!! Thank you.


AskDocWeb: Like it or not, the urine drug test is not perfect and depending on the manufacturer they can have error rates that range up to 43% when false positives and false negatives are added together (source: National Highway Transportation Safety Administration). Until better tests are devised, any suspect results should be confirmation by a Gas Chromatograph/Mass Spectrometer (GC/MS) test.

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