Comparison
Ketamine vs SSRIs
SSRIs are the first-line antidepressant for most people. Ketamine is typically considered after SSRIs and other options have not produced adequate response, or in specific clinical contexts.
Medically reviewed by: Pending medical review(draft)Last updated: June 4, 2026Evidence: Educational synthesis - not medical advice
Ketamine
SSRIs
Mechanism
NMDA-receptor antagonism with downstream effects on glutamate signaling, BDNF, and synaptic plasticity.
Inhibition of serotonin reuptake, gradually modulating serotonergic signaling and downstream neuroplasticity.
Evidence
Robust short-term antidepressant effect in TRD; durability requires repeat dosing and integration.
Largest body of long-term evidence across depression and anxiety; modest average effect size.
Onset
Hours to days for many responders.
Two to six weeks for typical response.
Duration
Days to weeks per session without maintenance.
Ongoing while taken as prescribed.
Side effects
Transient dissociation, blood pressure changes, nausea, dizziness; bladder effects with frequent recreational use.
Sexual dysfunction, GI symptoms, sleep changes, emotional blunting; discontinuation symptoms.
Access
Specialty clinics, IV/IM/intranasal; not first-line.
Primary care and psychiatry; widely available.
Best for
Treatment-resistant depression, certain acute scenarios, patients who have not tolerated or responded to standard options.
First-line pharmacological treatment of moderate-to-severe depression and several anxiety disorders.
Limits
Cost, access, durability without integration, limited long-term safety data at therapeutic doses.
Slow onset, partial response common, side-effect burden for some patients.
Educational use only. The content on this page is provided for general educational purposes and does not constitute medical advice, diagnosis, or treatment. Ketamine and related therapies carry risks and are appropriate only under qualified medical supervision. Always consult a licensed healthcare professional about your individual situation. Information may change as research evolves.