Tested positive for cocaine, but never touched the stuff

Originally Published: March 7, 1997 - Last Updated / Reviewed On: July 24, 2009
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Dear Alice,

My dad requires me to take weekly drug tests since he found out that I was smoking marijuana. My first test came back positive for marijuana and cocaine. I was not surprised about the marijuana because I had only been clean for five weeks, but I have never done cocaine. Is there anything that could have triggered a positive result? Could opium or mushrooms or any other drug possibly trigger this positive result?

Dear Reader,

If done correctly, drug testing for cocaine is pretty accurate. Most drug tests that check for cocaine look for benzoylecgonine, a product of the body's metabolism of the drug. Other illegal drugs, including opium and psilocybin, do not produce this byproduct and so can't cause a false positive for cocaine. Rarely, marijuana may be laced with other substances; accidentally using cocaine in this way could make someone test positive. However, benzoylecgonine can only be detected in urine for around three days after using cocaine. Your five weeks clean at the time of the test probably means that cocaine-laced marijuana isn't the culprit in your case.

That said, some medications and medical conditions can sometimes trigger a false positive for cocaine. These include:

  • Amoxicillin
  • Topical anesthetics derived from cocaine (does not include lidocaine or novocaine)
  • Liver disease
  • Kidney disease
  • Diabetes

One last possibility for a false positive is ingesting coca, the plant from which cocaine is derived. Coca leaves, particularly when brewed as a tea, are popular in a handful of countries but banned in the United States.

Since it sounds like you took an at-home drug test, there could be an increased likelihood of user error or false positives. A more specific secondary test, preferably by a professional, would need to be performed in order to figure out for sure whether it was cocaine, a different substance, or an error with the first test that caused the positive.

The U.S. Department of Health and Human Services and the Substance Abuse and Mental Health Services Administration (SAMHSA) recommend asking your health care provider whether your prescriptions might interfere with a drug test. Since you aren't using cocaine or other illegal drugs, this information should help you and your father understand the significance of the positive result.
Alice

July 21, 2009

21572
Just an FYI...

Extasy/EX/Molly/MDMA/LSD/etc. can all be "cut" or laced with cocaine, heroin, and numerous other substances. The source of any other substances you may have taken before...

Just an FYI...

Extasy/EX/Molly/MDMA/LSD/etc. can all be "cut" or laced with cocaine, heroin, and numerous other substances. The source of any other substances you may have taken before testing positive for cocaine should considered in your analysis.

June 16, 2006

21034

Alice,

...

Alice,

Another possibility to this question would be the fact that cocaine was in contact with some of the marijuana that the reader smoked; perhaps they were carried or handled together, or perhaps someone who was preparing the blunt had been handling cocaine prior to this. It is also a common occurrence in upper class marijuana use, to sprinkle cocaine on the joint, as a status symbol or to put a slight upper on the tiring effects of marijuana.