Medical Marijuana: A Nurse’s Primer

Illustration by J Paradisi.

Since I wrote “Marijuana Legalization and Potential Workplace Pitfalls for Nurses Who Partake” in July 2014, a few things have changed. For one, Measure 91 passed in Oregon, making it the third state to legalize recreational marijuana. Medical marijuana, however, has been legal since 1998 in Oregon, currently one of 23 states nationwide.

Also, when I wrote the earlier post, I was an infusion nurse—now, as an oncology nurse navigator, I’m asked about medical marijuana often, and I need to know the answers, as do all nurses practicing in states with legalized medical marijuana. Nurses working in oncology, emergency departments, pain management, infusion clinics, and pediatrics have high exposure to patients with medical marijuana cards.

By ‘knowledge,’ I don’t mean knowing everything, but knowing where to find what you need to know. In Oregon, for example, information about medical marijuana is found at the Oregon Medical Marijuana Program (OMMP). The Web site includes qualifying diagnoses, a downloadable handbook, an application packet with instructions, and a list of approved dispensaries. While retail issues surrounding recreational marijuana are still being sorted out, medical dispensaries in Oregon sell recreational marijuana to clients aged 21 and older.

Patients using medical marijuana are as diverse as the illnesses and side effects they use it to treat: PTSD, seizure disorders, chronic pain, inflammatory illness, and of course the adverse effects of chemotherapy, including nausea and vomiting, anxiety, sleeplessness, anorexia, and hot flashes associated with endocrine suppression therapy.

As they must with all prescribed medications, nurses caring for patients using medical marijuana need to become familiar with potential adverse effects. Oncology patients experience a host of treatment-related effects—teasing out which medication they may arise from is difficult. For instance, medical marijuana is commonly used to treat chemotherapy-induced nausea and vomiting. But nausea and vomiting  can also be symptoms of marijuana toxicity. Hypotension, a symptom of dehydration common with chemotherapy, can also be a sign of marijuana toxicity.

When smoked, cannabis enters the bloodstream rapidly; since patients can feel the drug’s effects in minutes (or less), they may find self-regulation easier in terms of dosage and other factors. Edible forms of marijuana, however, can take from 30 minutes to three hours to enter the bloodstream. This lag time may prompt some patients to repeat dosing sooner than recommended, leading to drowsiness, muscle weakness, hypotension, disorientation, or nausea and vomiting. Edibles are absorbed faster on an empty stomach—counsel patients with anorexia or other potentially relevant conditions accordingly. A single baked good, like a cookie, may contain several doses.

Like all medications, cannabis products should be stored in their original containers, clearly labeled, with dosages noted. And as with all medications, alcohol, and tobacco products, they must be kept out of the reach of children.

With the legalization of recreational marijuana, patients may be inclined to forgo medical marijuana cards and purchasing from a dispensary. While there are no studies I know of to prove this to be harmful, molds can grow on marijuana. Product can also be contaminated with E. coli from soil.

In Oregon, medical marijuana dispensaries are required to test their products for mold, bacteria, and pesticides. While some questions have been raised about the adequacy of existing tests for certain pesticides, marijuana not purchased at a dispensary will not be tested at all and its strength and proper dosing will not be verifiable. The testing used by dispensaries provides an extra layer of safety for patients with compromised immune systems and oncology patients with neutropenia.

Hospital policies. Cannabis, medical or recreational, is still prohibited on hospital campuses, even in states where it is legal, in keeping with their policies on alcohol and tobacco. Nurses should become familiar with each employer’s policies for medical marijuana and how to handle encounters with patients expecting to use it during appointments or hospitalizations. Hospice workers may have a different set of rules about its use in their facilities.

The reality is that education for patients using medical marijuana is not vastly different from that for prescribed narcotics, the social responsibility not vastly different from that for imbibing alcohol. With any of these, overuse can cause symptoms of toxicity.