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Psilocybin and SSRIs

Reduces effects

Antidepressant, SSRI · also: fluoxetine, prozac, sertraline, zoloft, lustral

SSRIs usually make mushrooms feel weaker rather than dangerous, and the main practical risk is redosing when the first dose seems not to work.

Often a weaker experience than the dose would normally produce, sometimes much weaker. People then redose, which is where the actual risk sits: the second dose can arrive as the first is still climbing.

Claims re-checked against the cited sources:

Why it happens

The usual explanation is that weeks of SSRI treatment reduce the number or responsiveness of 5-HT2A receptors, which psilocin needs, though this has not been confirmed directly in humans. Psilocin is a direct receptor agonist, not a serotonin releaser, so the classic SSRI-plus-MDMA serotonin syndrome mechanism does not transfer cleanly. In a two-week trial escitalopram did not change psilocin blood levels.

What is known

Mainly from surveys: in a 2023 analysis of 611 reports, about half of people taking mushrooms on an SSRI said the effects were weaker than expected. Controlled data is limited and more mixed: a 2022 trial in healthy volunteers found two weeks of escitalopram did not change psilocybin's positive mood effects but reduced anxiety, 'bad drug effects' and cardiovascular effects, and its authors note that longer treatment may differ. Serotonin syndrome from an SSRI plus psilocybin is rarely reported despite very large numbers of people doing it, which fits the mechanism: psilocin is a receptor agonist, not a serotonin releaser.

2023
In an online survey of 611 reports of taking mushrooms with an antidepressant, the estimated probability of weaker than expected effects was 0.47 for SSRIs (0.55 for SNRIs, 0.29 for bupropion). Gukasyan et al., Journal of Psychopharmacology 2023
2023
In the same survey, a reduced effect was also reported after stopping an SSRI or SNRI and appeared to persist up to 3 to 6 months. Gukasyan et al., Journal of Psychopharmacology 2023
2022
In a randomized crossover trial in healthy volunteers, 14 days of escitalopram (10 mg then 20 mg) before 25 mg psilocybin had no relevant effect on positive mood effects but reduced bad drug effects, anxiety and cardiovascular effects, and did not change psilocin pharmacokinetics; the authors call for studies with longer pretreatment. Becker et al., Clinical Pharmacology & Therapeutics 2022
2026
Fluoxetine's active metabolite norfluoxetine has an elimination half-life of 4 to 16 days, so active drug persists for weeks after stopping. PROZAC (fluoxetine) US prescribing information, DailyMed

Safety guidance

  • Expect a weaker experience and plan for the redosing trap, not for serotonin syndrome.
  • Decide your total dose before you start and do not redose during the come-up.
  • Do not taper or stop an antidepressant to take mushrooms without your prescriber; discontinuation symptoms are real, and paroxetine is among the harder ones to stop.
  • Fluoxetine lingers for weeks after the last dose, longer than other SSRIs.
Do not stop a prescribed medication on your own. Stopping or skipping a prescribed drug to take mushrooms can be more dangerous than either alone. Talk to whoever prescribes it.

When to seek help

Get medical help for confusion with high fever, heavy sweating, muscle rigidity or jerking, or a very fast heart rate; this is rare with this combination but needs urgent care if it happens. Emergency red flags.

Common questions

Will my SSRI block mushrooms completely?

Usually not completely. In one survey about half of SSRI reports described weaker than expected effects.

Is serotonin syndrome a big risk with SSRIs and mushrooms?

It is rarely reported. Psilocin acts on receptors directly rather than releasing serotonin, so the MDMA-style risk does not transfer cleanly.

Should I stop my SSRI before a trip?

Not on your own. Talk to your prescriber; stopping suddenly can cause discontinuation symptoms, and survey data suggest effects may stay blunted for months anyway.

Sources

  1. [1]Gukasyan et al., 'Attenuation of psilocybin mushroom effects during and after SSRI/SNRI antidepressant use' (2023)
  2. [2]Becker et al., 'Acute effects of psilocybin after escitalopram or placebo pretreatment' (2022)
  3. [3]Sarparast et al., 'Drug-drug interactions between psychiatric medications and MDMA or psilocybin' (2022)

How we research this: sources, evidence grading, review and updates.

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