In some research, we must defer to ethics and accountability. Sometimes, anecdotal history is just not enough. With so little responsible research done on the question, there is some risk in assessing whether it is safe to consume cannabis while on medications.

History has encouraged and facilitated self-medication, but with the universal access to some medications, we could be mixing risk with risk to say there is no problem.

One up front problem is that cannabis treats many of the same conditions with specific prescription regimens. With a great deal of attention paid to issues of stress, depression, and difficult to diagnose and treat medical problems, there is the chance that people will mix contraindicated remedies and/or overdose with combinations of treatments.

What does contraindicated mean?

In pharmaceutical environments, “contraindicated” refers to a situation in which a drug may be harmful to a patient. This might result from other conditions affecting the patient.

Relative contraindication warns of mixing two medications. Some combinations, for instance, may cause nausea.

Absolute contraindication warns that a medication could threaten the patient’s life. Some combinations, for example, could degrade kidney or liver functions.

The former requires you to weigh the benefit and risk, and the later should be avoided except in the most extreme situations. And, there are those that affect people with allergies, hypertension, or women who are pregnant or plan to be.

A great deal is known about the risks in consuming combinations of prescription and over-the-counter medications. The Food and Drug Administration requires deep and broad research and development before it approves medications. But, there are no such requirements for cannabis breeders and producers. Some studies have followed interactions, but research is not part of the cannabis seed-to-purchase process.

Consuming marijuana with these drugs presents a risk:

Antidepressants: There is a specific concern about the interaction between cannabis and TCAs (tricyclic antidepressants). The combination may cause tachycardia, an abnormally fast heartbeat and hypertension along with confusion, hallucinations, mood swings, and restlessness. Tachycardia can be fatal and is often seen in chronic cannabis users. Cannabis used in combination with MAOI antidepressants and SSRIs may have adverse effects because of the blood pressure and sedative effects, but no significant research has examined these risks. And, incidents are thought to be mild.

Benzodiazepines: People take Benzodiazepines like Valium and muscle relaxants to reduce anxiety and tension. They often produce drowsiness and mild to moderate sedation. Consuming cannabis in combination with such meds can reduce breathing, heart rate, and alertness. Mixing large doses and frequency of the prescriptions and cannabis will exacerbate these effects.

Diabetes medications: Some research says regular cannabis users have systems that control their blood sugar levels. Other research says they are at higher risk of prediabetes.

One study reported by the American Diabetes Association found, “Specifically, the frequency and amount of consumption of soda, cheese, salty snacks, pork, and alcohol was higher in cannabis users.” Such a diet exacerbates problems for diabetics, but there is no report of cannabis interacting directly with diabetic controls. So, diabetics are encouraged to monitor their cannabis consumption carefully.

Ketoconazole: This is an antifungal medication that inhibits cytochrome P450 enzymes. Taken with cannabis, it also inhibits the degradation of THC, effectively increase the potency of THC.

Lithium: Lithium treats bipolar disorder, and cannabis has properties that reduce depression and agitation. So, many bipolar patients self-medicate with cannabis.

Regular and long-term use of lithium risks chronic renal failure, and cannabis produces no such risk. But, since Lithium (and similar drugs) and cannabis treat the same symptoms, mixing them without moderation and monitoring risks doubling their effects.

Prozac: Fluoxetine (Prozac) inhibits production on cytochrome P450 enzymes like ketoconazole. It reduces the metabolism of THC and increases the concentration of THC risking mania and psychosis.

Rifampin: Rifampin treats tuberculosis and Legionnaires' disease by triggering the activity of cytochrome P450 enzymes. This accelerates the breakdown of THC and its desired effects.

Warfarin: Blood thinners like Warfarin treat and prevent blood clots. Cannabis may inhibit warfarin’s performance complicating bleeding issues.

Viagra: Viagra and other treatments for Erectile Dysfunction break down in the liver. Properties in cannabis can inhibit the functioning of the enzymes that aid that metabolism.

What’s a patient to do?

Occasional light use of cannabis should not add risk for those on a prescribed medication regimen. But, any decision to treat serious medical conditions with cannabis should have a doctor’s approval. You should not consume cannabis without full disclosure to your doctor.

It’s to your distinct health advantage to tell your doctor about the frequency of your cannabis habit and the cannabis strains preferred. You are in the best position to judge if the doctor’s reaction is a knee jerk rejection of cannabis benefits.

But, with or without supporting research, the risks cannabis presents to combining cannabis with those medications listed here deserve serious attention. You don’t need advice to avoid consuming cannabis with antipsychotics, with anything producing tachycardia, or with anything affecting liver metabolism.

This column does its best to avoid medical advice rather than confuse or misdirect readers. Neither a medical or research professional, I am in no position to recommend treatment of very significant medical problems. And, I am concerned that we know so little about the mechanism of action between cannabis and pharmaceuticals.

We do know that no one has died directly from cannabis consumption. And, I know of no credible reports of anyone dying from a contraindicated combination with medications. But, patients with established heart conditions, diabetes, hypertension, and psychosis must be cautious.