Roughly ten percent of Americans smoke cannabis and about the same percent are on antidepressants, so it stands to reason that there are approximately a shitload of millions of Americans who use both concurrently. Strangely, there is not very much research on what effect the two classes of drug have when used in combination (or maybe it’s not that strange given how hard it is to do research on cannabis at all in this country).

Some folks at the news branch of Leafly, a website we greatly admire, recently tried to compile info on how cannabis can affect the use of various classes of antidepressants. While some types of psychiatric drugs had little no interaction with marijuana, some could spell trouble if used in tandem.

They found that in general, older antidepressants often had more adverse effects in general and so were more likely to show problems when combined with cannabis usage. Tricyclic antidepressants, for example have been shown in several case reports to cause potentially life-threatening interactions with cannabis such as a racing heartbeat. Forms of tricyclic antidepressants include doxepin, trimipramine (Surmontil), amitriptyline, and imipramine (Tofranil).

Monoamine oxidase inhibitors (MAOIs) haven’t actually been proven to react badly with marijuana use, but which causes so many other negative interactions with other drugs that abstaining from pot while using it is highly recommended. Forms of MAOIs include isocarboxazid (Marplan), phenelzine (Nardil), and tranylcypromine (Parnate).

Sedatives, while not strictly being classified antidepressants, are often prescribed to people suffering from depression. Since cannabis is itself a sedative, combining the two can cause extreme drowsiness and sleepiness. Prescription sedatives include zolpidem (Ambien), lorazepam (Ativan), clonazepam (Klonopin), and phenobarbital (Donnatal).

Many other classes of antidepressants have more benign interactions with marijuana. Selective serotonin reuptake inhibitors (SSRIs), including Lexapro, Paxil, Zoloft, Prozac, and Celexa, have had very few reported cases of mixing badly with marijuana, though there are isolated case studies suggesting that the two combined could cause hypermania in patients with bipolar disorder.

Serotonin and norepinephrine reuptake inhibitors (SNRIs) such as venlafaxine (Effexor XR) and duloxetine (Cymbalta), as well as norepinephrine and dopamine reuptake inhibitors (NDRIs) — a class including Wellbutrin, Forfivo XL, and Aplenzin — are both shown to have little or no negative interaction with cannabis.

It should be noted that while some antidepressants have much fewer negative interactions with marijuana, drugs have very different effects on different patients, and many doctors recommend that cannabis users abstain from use while introducing a new antidepressant to their body at least temporarily while they and a doctor work out the proper dosage for them.

Photo via Flickr user Victor