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Testing Positive for Marijuana in Urine

Ask the Expert from November/December 2011

Question: What do you do with the patient who tests positive for marijuana on a urine test?

Answer: To answer this question, I first need to have some more information. Did the patient inform you in advance that he was using marijuana, or was this result unexpected? Was the marijuana obtained legally (eg, as part of a medical marijuana regimen, authorized by a physician, or in a state that permits the use of medical marijuana)? Does the patient state that he is using this recreationally, or does he believe it is for a legitimate medical purpose?

Let’s say the patient is using the marijuana recreationally and this test result is unexpected. Your patient has most likely signed a written agreement stating, among other things, that he will not use illegal substances. He has broken this agreement by using the substance, and also by lying to you. If the Drug Enforcement Agency (DEA) or state medical board were to review your records and find ongoing use of marijuana, you might lose your DEA permit. Explain to the patient that you cannot afford to risk losing your ability to prescribe opioids for legitimate pain patients and that your condoning the use of marijuana would be a risk to you. I would tell him that he has a choice—either to continue smoking pot, in which case you will be unable to continue prescribing opioids for his chronic pain, or to stop using it. 

On the day you get back the positive tetrahydrocannabinol (THC) test, call the lab and ask for a quantitative cannabinoid test. You want to learn the baseline level of cannabinoids before the urine sample is thrown away. If marijuana has been used chronically, the urine may remain positive for several weeks even if the patient is no longer using it. If the patient agrees to stop smoking pot, ask him to return in a couple of weeks, and obtain another urine sample. Send it for quantitative THC analysis. The urine may still be positive for THC, but there should be a significant decrease in the quantity. Repeat again on the following visit and then intermittently to be sure he has not resumed its use. 

If the patient states he is using the marijuana to alleviate pain, to relieve nausea or anxiety, or to improve his appetite, offer him alternative treatments (yes, including an increased dose of analgesic—THC does relieve pain), but insist that he stop smoking pot.

If you are practicing medicine in a medical marijuana state and you believe that the patient’s use of marijuana is a medical one, you have the option of providing the patient with an authorization to purchase the marijuana legally. If so, be sure to document this in the chart. However, the policies of the DEA regarding medical marijuana are evolving, and at this point you may still face some risk of regulatory scrutiny.

Jennifer Schneider, MD, PhD
Internal Medicine, Addiction Medicine, and Pain Management
Tucson, AZ

Last updated on: December 16, 2011
First published on: November 1, 2011