Dear Dr. Mossman,
I practice in a state that allows medical marijuana use. A few of my patients have asked me to help them obtain marijuana for their conditions. How risky would it be to oblige?
Submitted by “Dr. J”
In recent years, public debate about marijuana has acquired 2 new dimensions: (1) the wishes and medical needs of people who seek marijuana for its purported health benefits, and (2) the role of physicians who practice where “medical marijuana” is legal. This article, the authors’ joint effort to address Dr. J’s concerns, hits 3 topics:
• the intersection of marijuana policy and health care in the United States
• the risks and possible benefits of marijuana use
• the medicolegal problems faced by physicians who might advise patients to use marijuana.
Two cannabinoids—dronabinol and nabilone—have received FDA approval as appetite enhancers and anti-nausea agents. Third-party payors usually cover these types of medications, but no insurer pays for medical marijuana.1 The Controlled Substances Act of 19702 classified marijuana as a Schedule I drug because of its abuse potential, lack of accepted medical applications, and uncertain safety. The FDA has not approved marijuana use for any medical condition.
Although people commonly speak of “prescribing” marijuana, physicians cannot legally do this in the United States. What physicians may do, in the 23 states that allow medical marijuana, is recommend or certify a patient’s marijuana use—an action that has constitutional protection under the First Amendment’s freedom of speech clause.3,4
A physician may complete documentation that a patient has one of the qualifying medical conditions for which the jurisdiction has legalized medical marijuana. Either the patient or the physician then submits that documentation to the appropriate government agency (eg, the state’s department of health).
If the documentation receives approval, the agency will issue the patient a registration card that allows possession of medical marijuana, with which the patient can obtain or grow a small amount of marijuana. The cannabinoid content of marijuana products varies considerably,5 and physicians who certify marijuana typically defer dosage recommendations to the patient or the dispensary.1
In states that allow medical marijuana, users may assert an affirmative defense of medical necessity if they face criminal prosecution.3,6 Possession of marijuana remains illegal under federal law, however, regardless of one’s reason for having it.7,8 Since October 2009, the Attorney General’s office has discouraged federal prosecutions of persons “whose actions are in clear and unambiguous compliance with existing state laws providing for the medical use of marijuana.”9 But given the remaining conflicts between state and federal laws, “the legal implications of certifying patients for medical marijuana remain unclear.”10
Physicians have few resources to instruct them on the legal risks of certifying medical marijuana. When Canada legalized medical marijuana, the organization that provides malpractice insurance to Canadian physicians told its members that “prescribing medical marijuana cannot be compared to prescribing prescription drugs” and recommended that physicians obtain signed release forms documenting that they have discussed the risks of medical marijuana with patients.11 For some risky approved drugs, the FDA has established a risk evaluation and mitigation strategy, but no such guidance is available for marijuana.
Highlighting the benefits and risks
Proponents of medical marijuana claim that Cannabis can help patients, and dispassionate experts acknowledge that at least modest evidence supports the benefits of using “marijuana for nausea and vomiting related to chemotherapy, specific pain syndromes, and spasticity from multiple sclerosis.”10 For several other conditions— HIV/AIDS, depression, anxiety disorders, sleep disorders, psychosis, Tourette syndrome—evidence of benefit is poor.12 Rigorous evaluation of medical marijuana is difficult because the plant contains hundreds of active chemical compounds. The chemical content of marijuana is highly variable, depending on its preparation and administration,10,13—one reason why only a few good randomized controlled trials of marijuana have been conducted.
Marijuana has several side effects and carries many health risks (Table 1).4,14-20
On the highway: Marijuana and driving
Marijuana use impairs driving ability.14 Following enactment of more lenient marijuana laws, several states have reported higher numbers of fatally injured drivers who tested positive for Cannabis21-23 and had a positive screen of tetrahydrocannabinol (THC) in driving under the influence cases.24,25 One study showed that a blood THC concentration >5 ng/mL (comparable to a blood alcohol concentration of 0.15%) increased the crash odds ratio to 6.6.25,26
Marijuana impairs reaction time, information processing, motor performance, attention, and visual processing.14,16,27,28 Drivers who are under the influence of marijuana make more driving errors, despite being cautious about how they react to traffic.29 Even after weeks of abstinence, previous daily users of marijuana display some cognitive processing and driving-related impairments.30,31