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My Policy on Marijuana

A clinician's policy on screening and prescribing controlled substances in the presence of illicit drugs, including recreational cannabis.
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Eight years ago, I adopted a policy in my clinical practice that I consider to be both prudent and within the intent of the federal law, which prohibits use of marijuana and considers marijuana to be an illegal substance.

It is clear that even low doses of tetrahydrocannabinol (THC) may, in susceptible individuals, cause mental status changes, perceptual distortions, and impaired judgment. At moderate to high doses, these problems are frequent (see Does Marijuana Cause Cognitive Impairment During Driving?).

The use of controlled substances by patients in a chronic pain practice presents a challenge to the clinician. In addition, even in states, cities, districts and Indian reservations in which recreational marijuana is now legal, the use of marijuana may often occur in conjunction with a high-risk lifestyle pattern.

Therefore, it is prudent to obtain urine or oral drug screens at the initial office visit and then randomly thereafter, with a frequency dependent upon stratified risk factors for substance misuse, abuse, addiction, and diversion.

In the event that the drug screen is positive for marijuana or any other illicit/illegal substance, I will not write for a prescription for any controlled substance—meaning that if the patient is receiving an opioid analgesic for pain from another prescriber, a new prescription will not be written.

Prior to my writing a prescription for opioids or other controlled substances, the patient must have a normal drug screen and give reassurance that he/she will no longer use any illicit substances. If there is another positive urine drug screen, he/she may be tapered from all controlled substances and a substance abuse protocol will be implemented.

My practice guidelines are based on a review of evidence-based universal precautions.1,2

Drug-Drug Interactions

The use of marijuana may interfere with the therapeutic effect of pain medications and also can increase cognitive dysfunction. Therefore, I strongly believe it is advisable that patients who are being managed in a pain practice abstain from the use of marijuana or other psychoactive substances likely to adversely affect their mental status.3

It is important to consider not only the immediate risks posed by smoking marijuana, but also the long-term risks as well, including the possibility of substance abuse. Moreover, evidence for the efficacy of marijuana in pain control is lacking: Campbell et al performed a qualitative systematic review revealing that cannabinoids were not more effective than codeine in controlling pain and often had a central nervous system (CNS) depressant effect that limited their use in such settings.4

Campbell et al’s review cited several adverse effects (AEs) of marijuana use, including dry mouth, blurred vision, palpitations, tachycardia, and postural hypotension. The AEs occurred in patients who ingested between 10 and 20 mg of THC. Many of the 222 patients displayed AEs; the review documented one or more of the following dose-response related AEs: mental clouding, ataxia, dizziness, numbness, disorientation, disconnected thought, slurred speech, muscle twitching, impaired memory, dry mouth, and blurred vision. When the level of THC ingestion reached 20 mg, sedation occurred in 100% of patients.4

Legal Implications

In my 2014 address to physicians attending the annual meeting of the American Academy of Pain Medicine, Phoenix, Arizona, I strongly advised them to not write for any controlled substances including opiates, to any patients testing positive for illicit drugs on urine drug screens drugs, even in areas where recreational THC is legal.5

I described a possible legal and medical malpractice situation if clinicians knowingly write a prescription for a controlled substance for patients who they are aware are concomitantly using marijuana. I discussed this hypothetical situation that very well could become a reality:

  • Assume that a patient was using marijuana and that the physician was aware of this use and nonetheless wrote for an opioid or another controlled substance.
  • Now assume that the patient went through a stop sign or traffic light and killed a 6-year-old girl.
  • Assume that the patient was charged with vehicular homicide, and the patient’s drug screen was positive for not only THC but also for the opioid the physician prescribed.
  • Conceivably, it might be construed that it was not the THC that caused the accident resulting in the child’s death, but possibly it was the opioid the physician was writing with the knowledge that the patient was also using marijuana.
  • Potentially, that physician could be at risk for charges of negligence or malpractice.6-8

In addition to liability concerns, I believe that we also have an ethical responsibility to monitor patients very carefully to protect not only our patients, but also other individuals who conceivably could be injured by the actions of our patients. For this reason, since 1999, I have frequently lectured and written on the importance of monitoring patients to assess whether it is safe for them to drive and return to work when a physician writes a prescription for a controlled substance or any CNS active medication.

From a risk management perspective, it is foolhardy to continue writing opioids for patients known to be using/abusing marijuana or other substances deemed to be illegal (or even in situations where it is legal). In the event that the patient in question has a work or motor vehicle accident in which there is an injury or death, the clinician writing for the controlled substances—while having full knowledge that the patient was abusing an illicit drug capable of causing mental status changes, judgment and perceptual problems—would be in a difficult position to defend, since he/she provided the drug that may be linked to the tragic accident/fatality.

The question that remains to be addressed by case law is whether a health care provider treating a patient who is known to be a regular marijuana user and who tests positive on an office visit urine drug screen is at significant risk when provided controlled substances (including opiates) for chronic pain.

In a wrongful death situation, would that physician be considered to be sufficiently involved, having provided the controlled substance that was found on the urine drug screen following the death? I have this discussion with my patients and advise them that I am unwilling to risk my medical license or my freedom because of their wish to be involved in the use of recreational drugs.

Impaired Cognition: Test of Reaction Time

I have become increasingly concerned about the potential for driving accidents and work injuries in patients who are receiving CNS-active medication without appropriate monitoring. For nearly a decade I have implemented guidelines to improve driving and work safety, recognizing that an impaired patient can increase the risk for injury risk to himself/herself as well as to innocent pedestrians or other drivers and coworkers.

Last updated on: September 14, 2015
First published on: September 1, 2015
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