Will you refuse to treat me if I use cannabis?

No. Cannabis use is not disqualifying at our clinic. We ask about it because it is clinically relevant to monitoring and to interpreting your response, not as a screening test. What we do ask is that you be accurate with us, including about frequency and about the day of your session.

Does cannabis make ketamine work less well?

The best available human evidence suggests not. An observational study published in Psychiatry Research in 2023 found no significant difference in antidepressant outcomes between cannabis users and non-users receiving ketamine. That study was not randomized and could not address heavy daily use specifically, so we describe this as reassuring rather than settled.

Will cannabis make dissociation more intense?

Nobody has directly tested that combination, so we cannot tell you with confidence. Cannabis can produce dissociative effects of its own, which makes an additive effect plausible in theory. This uncertainty is exactly why we ask you not to use cannabis before a session and why we want to know if you have.

Do I need a different ketamine dose because I use cannabis?

There is no published human research establishing a cannabis-specific dosing adjustment for ketamine. Any clinic offering you a precise adjustment is extrapolating beyond the evidence. We dose based on weight and titrate based on your actual observed response, which handles individual variation regardless of its source.

How long before an infusion should I stop using cannabis?

We ask you not to use on the day of your session prior to the infusion. Beyond that we will not invent a precise window the research does not support. If you use daily and are considering a longer break before starting treatment, that is worth discussing at consultation rather than deciding alone.

Ketamine and Cannabis: What We Know, and What We Genuinely Don't

Why patients ask, and why some don't

Cannabis is legal in much of the country, medically available in more of it, and widely used in Tennessee regardless of either. So the question comes up constantly. It also goes unasked more often than almost any other medication question we field, because people worry that disclosing use will get them turned away.

We would rather clear that up at the start. Cannabis use is not disqualifying here. What it is, is clinically relevant information that changes how we monitor you and how we interpret your response. The rest of this article is our honest attempt to describe what the research supports, which is less than you might hope.

Where the two systems intersect

Ketamine's antidepressant mechanism runs through NMDA receptor blockade and the downstream glutamate signaling that follows, a chain we describe in how ketamine works.

The endocannabinoid system touches that same machinery. CB1 receptors sit on presynaptic terminals throughout the brain, and activating them reduces neurotransmitter release, including glutamate. A review in the European Journal of Neuroscience in 2018 examining cannabinoid and glutamate interactions noted that CB1 agonists and NMDA antagonists can both reduce inhibitory GABAergic tone on pyramidal neurons, one proposed route to the dissociative and perceptual effects both classes of drug can produce.

That is a real point of contact, and it is enough to make an interaction biologically plausible. It is not enough to predict the direction or size of one in an actual patient, which is a distinction worth holding onto whenever you read confident claims in either direction.

What the human outcome data shows

The most directly relevant study was published in Psychiatry Research in 2023. Researchers compared antidepressant treatment outcomes between cannabis users and non-users receiving ketamine and repetitive transcranial magnetic stimulation. In the ketamine group, cannabis use showed no main effect on symptom severity over the course of treatment, and mean improvement in depression scores was similar between users and non-users.

That is the strongest signal available, and it points toward cannabis use not meaningfully undermining ketamine's antidepressant benefit. It also comes with real limitations. The study was observational rather than randomized, cannabis exposure was not experimentally controlled, and it could not address whether heavy daily use, or use immediately before a session, behaves differently from cannabis use in general.

Separately, a small proof-of-concept study in the American Journal of Drug and Alcohol Abuse in 2021 gave ketamine infusions to eight adults with cannabis dependence as part of a behavioral treatment program. Ketamine was well tolerated with no adverse events, and cannabis use decreased significantly after the first infusion. Eight people is not a foundation for broad conclusions, but it does argue against the idea that cannabis users cannot safely receive ketamine.

What nobody has established

On dosing, the honest answer is that there is no published human research showing that cannabis use requires a different ketamine dose. Not evidence of no effect — an absence of study. Any clinic quoting you a specific adjustment for cannabis users is extrapolating.

On dissociation, the picture is similarly incomplete. Cannabis can produce dissociative and perceptual effects of its own, and a study using the same clinician-administered dissociation scale used in ketamine research found measurable dissociation from cannabis, though less than that produced by ketamine. What has not been tested is the combination. A 2011 study in Clinical Neuropharmacology examined CBD given before ketamine in healthy volunteers and found it amplified some activating effects while showing a non-significant trend toward reduced depersonalization. That is CBD, not THC, in volunteers without depression, which is several steps removed from the question most people are actually asking.

So the fair summary is this: the outcome data available is mildly reassuring, the dosing and dissociation questions are genuinely open, and anyone who tells you otherwise is filling gaps with confidence rather than data.

Why disclosure matters more than the answer

Because the interaction is uncertain, what protects you is not a rule about cannabis. It is your clinician knowing what is actually in your system.

Three practical reasons. Dissociation is the experience patients find most disorienting when it is unexpected, and if you have additional psychoactive material on board, we want that context before we interpret what you are experiencing. Cannabis affects heart rate, which matters when we are monitoring vitals through an infusion that typically raises blood pressure and pulse modestly on its own. And if your response to treatment is unusual in either direction, we need an accurate picture to work from rather than a guess.

Heavy daily use is also worth an honest conversation for a different reason. If cannabis is functioning as self-medication for the same symptoms that brought you here, that pattern is clinically meaningful in itself, and it belongs in the treatment plan. Our article on ketamine and recovery covers adjacent ground.

What we ask at Music City Ketamine

At consultation we ask about cannabis directly, in the same tone as any other medication question: what form, how much, how often, how recently. The answer does not go anywhere except your chart and your care.

We ask you not to use cannabis on the day of an infusion, before the session. This is a judgment call rather than a research-backed rule, and we will say that plainly. The reasoning is that we want a clean read on how you respond to ketamine itself, especially during your first few sessions when we are establishing your baseline. Introducing a second psychoactive variable makes that harder for both of us.

Marla reviews this alongside the rest of your medication list before each infusion, the same way she handles everything else that could affect monitoring or titration. What she is watching for is described in what Marla does during an infusion, and our pre-session guidance covers the practical side of the day itself.

Honest expectations

Ketamine is FDA-approved as an anesthetic; its use for depression and anxiety is off-label.

Cannabis use will not get you turned away here, and based on the evidence that exists, it does not appear to meaningfully reduce ketamine's antidepressant benefit. We are telling you that while also telling you the evidence base is small, mostly observational, and silent on several questions you might reasonably want answered.

If that combination of reassurance and uncertainty feels unsatisfying, we understand. It is the accurate description of what is currently known, and we would rather hand you that than a cleaner answer we cannot support. More on the conditions we treat is under depression and anxiety.