Note: I understand that this topic HAS been discussed previously, and some information is available by searching through all of the forums threads. I believe that this thread, however, provides a substantial amount of personal evidence, as well as new resources and citations for those interested in further research, to qualify creating a new thread. I hope I'm correct, but if not, please advise me and/or remove this thread or merge to a more appropriate place
Dextromethorphan (also known as DXM), present in many over-the-counter pharmaceuticals including cough syrups and cough & cold remedies, may cause false-positives for opiates on EMIT-style urine drug screens or other similar, inexpensive dipstick or one-step sample-cup urine drug tests. The following resources/citations show that false-positive opiate results caused by dextromethorphan intake are actually quite common with preliminary, rapid-result drug tests.
■ ASCP (American Society for Clinical Pathology) LabMedicine #41, p. 457-460: "Is Dextromethorphan a Concern..."
■ FAQ: VitroDiagnostic.com
■ LawyersAndSettlements.com: Potential Lawsuit/False Positive Drug Testing
■ Legal Bulletin 6.4: Urinalysis Drug Testing; Lewisburg Prison Project, Inc.
■ OregonHerald.com Workplace Drug Testing: "Drug Testing Does No Good"
■ Yale LabMed: Urine Drugs of Abuse by EMIT
I have quite a bit of personal experience regarding false-positive drug screen results caused by dextromethorphan/DXM, having had six or eight false-positive results myself in the past 6-months. As a methadone maintenance patient at a small, private clinic (operated by a single physician), I am required to submit a supervised urine sample once-per-week. And my personal experiences regarding this problem are in regards to two different styles of rapid urinalysis, a dipstick-style 7-panel test, and a one-step 5-panel sample cup. I will explain/describe these two tests in detail below.
I do understand that my personal experiences are only anecdotal, but I feel that they may be useful to other individuals who are drug-screened on a regular basis using inexpensive, preliminary EMIT tests, and are therefore still relevant information that meets the qualifications for this forum. If not, please advise me otherwise.
The first style of test that I am most frequently subjected to is an EMIT-style 7-panel dipstick test. This test has the following test-panels: THC (marijuana, hashish, etc.), COC (cocaine), AMP (amphetamine, methamphetamine), BZP (benzodiazepine; tests for the metabolite oxazepam), OPI (opiates incl. morphine, codeine, heroin, hydromorphone, high-doses of meperidine/demerol, and potentialy several other synthetic, morphine-related opioids), OXY (oxycodone), and MET (methdone). These tests are quite sensitive, and even if you are below the cutoff level for a certain substance, a (sometimes very) faint line will often appear, which the doctor usually (incorrectly) reads as a positive result.
The second style of test, a one-step sample cup with the 5-panel test built right into the cup, is one that I only see infrequently. It tests for only 5 substances: COC, BZP, OPI, OXY, and MET. I have noticed personally, and have confirmed with my doctor, that these tests are extremely sensitive, much moreso than the first style of test. Even if you are well below the cutoff level, you can have a positive test result (cocaine, for example, can show up on this test for up to a week or more).
And now, regarding dextromethorphan/DXM causing false positives on the OPI-panel of these drug-screens; in my experience, dextromethorphan can ABSOLUTELY cause a false-positive result, and depending on the type test, even therapeutic doses can sometimes cause false-positive results. At the start of my methadone treatment, I was continually receiving positive results for opiates (under the OPI-panel), even though the only opiate/opioid I was consuming was oxycodone, which shows up seperately under the OXY-panel. These tests were all of the first type I described (the 7-panel dipstick test). It took me a number of weeks before I was finally able to figure out that it was dextromethorphan that was causing these opiate-positive results. I was using dextromethorphan daily at the time to help slow the development of my tolerance to methadone, in doses that were several times larger than what is recommended therapeutically: between 60-90 mg per dose, once or twice each day. Once I made sure that I was only using therapeutic doses in the days running up to my test, I stopped getting the false-positive results for opiates.
With the second style of test that I described, I twice tested positive for opiates (again, under the OPI-panel, when I only should have tested positive under the OXY-panel) after using only therapeutic doses (15-30 mg) of dextromethorphan in the several days prior to my drug screen. These 5-panel tests are one-step sample cups, meaning that the results appear right on the side of the sample cup, immediately following the deposit of your sample. I had one of these false-positive results sent to a lab for GC/MS testing, which verified that I was negative for opiates and that my positive result was in error.
Some sources claim that EMIT-style drug screens are incorrect as much as 30% of the time, causing either false-positive or -negative results.
I now ensure that I do not take dextromethorphan AT ALL, in the 2-3 days leading up to my sample dates. Since I began this, I have not once tested positive incorrectly on any of my UA's. I believe that the reason DXM has the potential to cause false-positive test results may have something to do with it's structural similarity to several opioid analgesics. Dextromethorphan is the dextrorotatory enantiomer of levomethorphan, an opioid analgesic that is the methyl ether of levorphanol, which is a more potent, pure-opioid-agonist analgesic, used in the treatment of very severe pain. Also, dextromethorphan itself is known to have some painkilling properties, and it is a cough supressant, similar to several opiates used for this same purpose.
Please keep in mind that this is only my opinion. Your mileage may vary.