Psilocybin and St John's Wort

Caution

Herbal antidepressant · also: hypericum perforatum, hypericum, kira, jarsin

Psilocybin and St John's Wort: caution, the effect on a trip is unknown, and the bigger documented issue is how St John's Wort interacts with other medicines.

Unpredictable. Reported both to blunt effects and to leave them unchanged. The main documented hazard of St John's Wort is what it does to other prescribed drugs.

Claims re-checked against the cited sources: 2026-10-13

Why it happens

St John's Wort induces CYP3A4 and P-glycoprotein, lowering blood levels of many drugs, and it counts as a serotonergic drug in medicine labels. CYP3A4 is one of several enzymes that metabolise psilocin in lab work, so a change in psilocin levels is possible in theory but has not been measured.

What is known

Based on the mechanism, plus inconsistent anecdote. No controlled data on this pair.

2004: St John's Wort lowers plasma levels or effects of drugs including alprazolam, amitriptyline, digoxin, warfarin, simvastatin and oral contraceptives, likely through induction of P-glycoprotein and CYP3A4; combined with SSRIs it can cause serotonin syndrome. Izzo, 'Drug interactions with St. John's Wort (Hypericum perforatum): a review of the clinical evidence', Int J Clin Pharmacol Ther
2026: The lithium label lists St John's Wort among serotonergic drugs that raise serotonin syndrome risk. LITHOBID (lithium carbonate ER) US prescribing information, DailyMed (label version Aug 2026)
2024: Recombinant CYP3A4 metabolised about 40% of psilocin in vitro, but psilocin is cleared mainly by glucuronidation. Thomann et al., 'In vitro and in vivo metabolism of psilocybin's active metabolite psilocin', Front Pharmacol
2024: A 2024 systematic review found no human study of psilocybin with St John's Wort. Halman et al., 'Drug-drug interactions involving classic psychedelics: a systematic review', J Psychopharmacol

Safety guidance

Treat it as an unknown rather than as safe because it is sold over the counter.
If you take other medication, St John's Wort may already be interacting with it; ask a pharmacist.
Avoid combining it with SSRIs or other serotonergic drugs, with or without mushrooms.

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 urgent help for high fever, heavy sweating, muscle twitching or rigidity, or severe agitation or confusion, especially if you also take an antidepressant. Emergency red flags.

Common questions

Will St John's Wort weaken my trip?

Unknown. There are no studies, and the theory points in more than one direction.

Is it risky on its own with mushrooms?

No specific harm has been documented. The clearer risks come from combining it with prescription drugs.

Can it affect my birth control?

Yes. Reviews report it can lower oral contraceptive levels; ask a pharmacist.

Sources

[1]Izzo, 'Drug interactions with St. John's Wort (Hypericum perforatum): a review of the clinical evidence' (2004)

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

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