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    drug screening
    djblynn posted:
    I am new to pain management and they did a urine drug test. The test showed that I had taken cocaine and meth which I have never taken in my entire life! What could cause a false positive? I've been sick with an upper respiratory infection for several weeks and have been prescribed zpack, doxycycline, levaquin, cryoheptad, antipyrine and benzocaine eardrops, oral steroids, steroid injection, Flonase, asthma inhalers, advair discus, and am on trileptal, flexeril, and other meds for fibromyalgia & trigeminal neuralgia. Can any of these meds cause a false positive?
    djblynn responded:
    They sent the urine for further testing to the local hospital who sent it to a lab.
    lorigibs40734 responded:
    I'm very sorry about your predicament. There can be a false positive for those drugs if you take certain medications. Some antibiotics and over the counter meds can give a false positive.

    Since they sent it to the hospital, who sent it to a lab, they'll probably figure out which meds gave the false positive. And they should be able to treat you at a pain management clinic.

    djblynn replied to lorigibs40734's response:
    Thanks for replying. I have been very upset about this because I have done nothing wrong. The lab will surely figure it out.
    ctbeth responded:
    Holy Cow!

    The strengths and limitations of Urine Drug Screens need to be fully understood in order to perform the correct screen and also to correctly interpret the results.

    All positive results on immunoassay are presumptive until confirmed using GC-MS (gas chromatography-mass spectrometry )

    It would seem as if you had the quick and easy immunoassay test, which indicated some problems, presumably.

    One major problem with immunoassays is a false-positive result.

    Therefore, a more specific confirmatory test, such as GC-MS, is needed to confirm a positive finding with an immunoassay.

    GC-MS is more accurate than an immunoassay, but it is more expensive and time consuming.

    GC-MS breaks down drug molecules into ionized fragments and identifies substances based on mass-to-charge ratio using a mass spectrometer.

    Medication histories are important in order to anticipate false-positives as well as differentiate between drugs used for legitimate medical purposes and drugs of abuse.

    For example, Amoxicillin can cause a false positive for cocaine.

    Pseudophed, Phenylephrine, both de-congestants, can show a false positive for methamphetamine.

    You can do a search of any university's School of Pharmacy to find further info. I'm certain that there are many more meds that can cause false positives for various substances.

    You can look each agent up separately, so write a list of every med that you took within the month before the urine immunoassay test.

    Once the results of the GC-MS are known, it will show the meds that you've actually taken.

    The waiting is the tough part, I know, right?

    Have you made arrangements for your MD to phone you when the result is known, or must you wait for your next appointment?

    I hope you'll let us know.
    Try not to worry, although it can be tough.


    77grace replied to ctbeth's response:
    Hi CTB,
    Where in the world do you get all this information???
    This is really a problem tha they should address,not fair to the person thay are messing with!
    Hi djblynn,
    I just wanted you to know that I really feel for you and I am praying that this can be resolved!
    Take care 77grace
    An_251029 responded:
    I have worked for a lab that did drug screenings they are about 75% correct. Sometimes less. The doctor should know that there are false positives. But, sometimes Benzocaine eardrops may cause you to have a false positive for cocaine and asthma inhalers sometimes have been known sometimes to give a positive methamphetamine positive. Just ask the doctor to retest you or to split your urines in two.
    ctbeth replied to An_251029's response:
    ...and this is why it's vital for us to inform our MD, or his/ her staff, of all Rx and OTC meds that we've taken within the past few weeks-to-a month of the urine test.

    The time to inform of these changes is BEFORE the urine drug screen, NOT after a dirty (positive) urine.

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