⛔ Dangerous — Serotonin Syndrome Risk
MAOIs (monoamine oxidase inhibitors) can dangerously potentiate psilocybin and trigger serotonin syndrome, a potentially fatal condition.
Mechanism of Interaction
MAOIs (monoamine oxidase inhibitors) — including prescription antidepressants such as phenelzine (Nardil), tranylcypromine (Parnate), isocarboxazid (Marplan), and selegiline (Emsam) — block the enzyme that breaks down serotonin and other monoamines. Psilocybin acts on the serotonergic system (primarily the 5-HT2A receptor). Combining a serotonergic psychedelic with a drug that prevents serotonin breakdown can cause an unpredictable and dangerous buildup of serotonin, known as serotonin syndrome, which can be fatal.
This risk is also relevant to substances outside conventional prescriptions: harmaline and related beta-carbolines in ayahuasca are also MAOIs, and the same warning applies to any MAOI-containing preparation.
Harm Reduction Guidance
- Never combine psilocybin with an MAOI while it is active in your system.
- A minimum wait of 2 weeks after stopping an MAOI is the commonly cited harm-reduction figure, but this is not a guarantee of safety — some MAOIs and their metabolites can persist longer, and individual clearance varies.
- Always consult the prescribing physician before stopping an MAOI, and confirm timing with them rather than relying solely on general online guidance.
- Disclose any MAOI use (including supplements or plant medicines with MAOI activity, such as Syrian rue or ayahuasca) to anyone assisting you, and to a healthcare provider if you experience symptoms.
🚑 When to Seek Emergency Help
Serotonin syndrome can present with agitation, confusion, rapid heart rate, high blood pressure, dilated pupils, loss of muscle coordination, muscle rigidity, heavy sweating, diarrhea, and high fever. This can be fatal. If these symptoms appear after combining psilocybin with an MAOI (or any serotonergic drug), call emergency services immediately.
⚠️ Medical Disclaimer
This page is for educational and harm-reduction purposes only and does not constitute medical advice. Psilocybin remains illegal in most jurisdictions. Always consult a qualified physician or pharmacist before combining any substance with a prescription or over-the-counter medication, especially psychiatric medications, mood stabilizers, or opioids. If you or someone with you develops agitation, confusion, a racing heart, high fever, muscle rigidity, or seizures after combining substances, call emergency services (or your local equivalent of 911/999/112) immediately — these can be signs of serotonin syndrome, a potentially fatal condition.