TL;DR
- •Ketamine is an NMDA-receptor antagonist; psilocybin is a serotonin 5-HT2A receptor agonist. Both produce psychedelic states and rapid antidepressant effects but through fundamentally different pharmacology.
- •Ketamine is legal in the United States, FDA-approved as an anesthetic, and prescribed off-label for depression by physicians experienced in mood-disorder treatment. Sublingual at-home administration is widely available.
- •Psilocybin is Schedule I federally: illegal to possess or prescribe outside of FDA-authorized clinical trials and Oregon's Measure 109 supervised-use service centers. Australia approved limited psychiatrist-led use in 2023.
- •Goodwin 2022 (NEJM) showed a single 25mg dose of synthetic psilocybin produced a 37% remission rate at week 3 in treatment-resistant depression: encouraging but with regulatory access still years away from broad availability.
- •Carhart-Harris 2021 (NEJM) compared psilocybin to escitalopram head-to-head: comparable depression outcomes, with psilocybin showing some secondary measure advantages.
- •Ketamine produces antidepressant effects within hours; psilocybin produces them after a single 6-8 hour session. Maintenance schedules differ: ketamine typically weekly-to-monthly; psilocybin trials use single doses or every-few-months dosing.
- •For patients seeking a psychedelic-mechanism antidepressant available today, ketamine is the only legal at-home option in the US.
Side by side
Ketamine
Racemic ketamine (NMDA antagonist)
NMDA-receptor antagonist
What it treats
Off-label: treatment-resistant depression, anxiety, PTSD, chronic pain, FDA-approved: anesthesia
Mechanism
Blocks NMDA glutamate receptors, producing an acute glutamate surge, BDNF-mediated synaptic plasticity, and rapid antidepressant effect. Dissociative experience emerges from disrupted thalamocortical signaling and is generally shorter than psilocybin's effect.
Strengths
- •Legal and prescribable today: sublingual at-home option available
- •Rapid onset (hours, not weeks)
- •Decades of safety data in anesthesia and surgical sedation
- •Established maintenance protocols and physician training
Limitations
- •Off-label use for depression, not FDA-approved specifically for psychiatric indications
- •Direct-pay model in at-home settings; in-clinic IV often not insurance-covered
- •Bladder toxicity with frequent high-dose chronic use (recreational pattern, not therapeutic)
- •Dissociation is shorter and less mystical-character than psilocybin for most patients
Psilocybin
Psilocybin (5-HT2A agonist)
Serotonergic psychedelic (Schedule I)
What it treats
Investigational: treatment-resistant depression, end-of-life distress, alcohol/tobacco use disorder, OCD
Mechanism
Active metabolite psilocin is a serotonin 5-HT2A receptor agonist producing 4-6 hour psychedelic experiences with ego dissolution, sensory shifts, and emotional release. Antidepressant effect is hypothesized to come from neuroplasticity changes and the experiential content of the session.
Strengths
- •Strong RCT data: Goodwin 2022 NEJM showed 37% remission at week 3 with a single dose
- •Compared to escitalopram (Carhart-Harris 2021 NEJM): comparable primary outcome, some secondary advantages
- •Single-session dosing may suffice (vs ongoing ketamine maintenance)
- •Lower potential for chronic-use side effects (single dose at intervals)
Limitations
- •Schedule I federally: only legal access is Oregon supervised-use service centers (state-only legalization) or FDA clinical trials
- •Australia approved psychiatrist-prescribed use in 2023; most patients globally still have no legal access
- •Each session requires 6-8 hours of in-clinic supervision plus integration
- •Cost in available channels (Oregon, Australia) ranges $1,500-$10,000+ per session
- •Not appropriate for patients with personal or family psychotic-spectrum history
Which one for your situation?
If:
You want a psychedelic-mechanism antidepressant available legally today in the US
Verdict:
Ketamine: the only currently-legal option for at-home psychedelic treatment of depression
If:
You live in Oregon and qualify for licensed psilocybin services
Verdict:
Either option valid, but consider cost ($1,500-2,500+ per psilocybin session vs $349/month at Tovani)
If:
You want a single-session treatment with minimal ongoing maintenance
Verdict:
Psilocybin (where legally available): single high-dose sessions are the published protocol
If:
Family or personal history of psychotic-spectrum illness
Verdict:
Avoid both classical psychedelics: ketamine is sometimes used with caution, but psilocybin is contraindicated
If:
You want maintenance dosing flexibility based on response
Verdict:
Ketamine: established induction + maintenance protocols with dose flexibility
Where ketamine fits
Tovani provides sublingual ketamine via telehealth in Florida, New Jersey, and California: the legally-available psychedelic-mechanism option in the US for depression, anxiety, and PTSD. For patients drawn to psilocybin's mechanism, ketamine offers a similar rapid-onset paradigm shift without the regulatory and access friction.
Both ketamine and psilocybin produce mood response within hours-to-days of the first session. Ketamine: legal, at-home, $349/month at Tovani. Psilocybin: Schedule I in the US except Oregon supervised-use (~$1,500-2,500+ per session) and FDA trials.
5-minute screening · Reviewed by a board-certified physician · FL, NJ & CA
Frequently asked
Is psilocybin legal in the United States?
Federally, no: psilocybin remains Schedule I, meaning the DEA classifies it as having no accepted medical use and high abuse potential. The only legal access pathways are (1) FDA-authorized clinical trials, (2) Oregon's Measure 109 licensed psilocybin service centers (in-state use only, $1,500-2,500+ per session), and (3) Colorado's analogous program rolling out. Several other states are considering similar legislation.
Will psilocybin be FDA-approved soon?
COMPASS Pathways and other sponsors have advanced psilocybin programs through Phase 2 with positive results (Goodwin 2022). Phase 3 trials are ongoing. FDA approval is plausible by 2027-2028 if Phase 3 data replicate Phase 2, but timelines for psychedelic drug approval have been unpredictable. See MDMA's FDA rejection in August 2024 despite Phase 3 efficacy data.
Which mechanism is better for depression: NMDA or 5-HT2A?
Both produce rapid antidepressant effects in published trials at comparable response rates. The mechanisms are distinct: ketamine acts through glutamate via NMDA blockade; psilocybin through serotonin via 5-HT2A agonism. Some patients respond to one but not the other. They're not interchangeable. For now, ketamine is the only one accessible to most US patients without joining a clinical trial.
Can I use ketamine while waiting for psilocybin to become legal?
Yes. Many patients drawn to psilocybin's mechanism choose ketamine in the interim. It's legally accessible today, has decades of safety data, and produces a similar rapid-onset antidepressant effect through a different but related pathway. Ketamine and psilocybin aren't direct substitutes for each other, but for depression specifically, both offer mechanism-distinct options compared to SSRIs.
Is the experience similar?
Different. Ketamine produces shorter (60-120 min at therapeutic doses), more dissociative and ego-detached experiences. Psilocybin produces longer (4-6 hours), more visual and emotionally-rich experiences with stronger mystical-experience character. Some patients prefer one over the other based on temperament and goals.
References
- Goodwin GM et al. 2022, New England Journal of Medicine. Single-dose psilocybin RCT in treatment-resistant depression: 37% remission rate at week 3 with 25mg synthetic psilocybin, establishing the modern evidence base for psilocybin-assisted therapy. PMID 36322843
- CarhartHarris RL et al. 2021, New England Journal of Medicine. Trial of Psilocybin versus Escitalopram for Depression: comparable primary outcome with psilocybin showing some secondary measure advantages. PMID 33852780
- Murrough JW et al. 2013, American Journal of Psychiatry. Ketamine RCT in treatment-resistant depression: 64% response vs 28% placebo, establishing ketamine's rapid antidepressant effect. PMID 23982301
- Hughes B et al. 2025, Cureus. Comparative review of ketamine and psilocybin as therapeutic options for depression, anxiety, and trauma-related disorders. PMID 40970030