Short answer
Common psilocybin side effects include headache, nausea, anxiety, and a temporary rise in heart rate and blood pressure. Serious risks are rare but real: psychotic or manic episodes in vulnerable people, dangerous behavior while impaired, and lasting visual disturbances. People with a personal or family history of schizophrenia, psychosis, or bipolar disorder, people with significant heart disease, people taking lithium, and pregnant people should generally avoid it.
Key takeaways
- Most side effects are short-lived: headache, nausea, fatigue, and anxiety during the session.
- The biggest red flag is a personal or family history of psychosis or bipolar disorder.
- Heart disease and uncontrolled high blood pressure are reasons to get a doctor involved first.
- In Oregon's licensed program, 1.2% of studied clients had a severe behavioral reaction.
Who should not take psilocybin
Clinical trials screen people out for good reasons, and those screening rules are the best guide we have.1 Psilocybin is generally a bad idea, or at least needs a doctor's direct involvement, if you:
- Have a personal or family history of schizophrenia, other psychotic disorders, or bipolar I disorder. This is the most important one. Psilocybin can trigger psychotic or manic episodes in people who are predisposed.
- Have heart disease, a history of stroke, or uncontrolled high blood pressure. Psilocybin temporarily raises both heart rate and blood pressure.
- Take lithium. The combination has been linked to seizures.7
- Take other psychiatric medications, including antidepressants, antipsychotics, or MAO inhibitors, without talking to your prescriber. See interactions.
- Are pregnant or breastfeeding. There's no safety data.
- Are under 21. Legal programs don't serve minors, and it hasn't been studied in adolescents.
- Are in an acute crisis, such as active suicidal thoughts, without a clinical team involved.
- Have a seizure disorder or are in a situation where you can't be in a safe place with a sober person for the full experience.
Common side effects
In a pooled analysis of 110 healthy volunteers across eight studies, side effects were mostly short-lived and mild.2 The ones you're most likely to notice:
| Side effect | When | Notes |
|---|---|---|
| Headache | Later that day or the next day | Among the most common side effects in trials |
| Nausea | First hour or two | Usually passes; vomiting is less common |
| Anxiety or fear | During the session | Common at some point, especially at higher doses |
| Higher heart rate and blood pressure | During the session | Returns to normal as effects fade |
| Fatigue | The rest of the day | Plan nothing important afterward |
Rare but serious risks
Psychiatric reactions
In predisposed people, psilocybin can trigger psychosis or mania that outlasts the drug. That's why the screening rules above exist.1
Suicidal thoughts in vulnerable patients
In the 2022 Phase 2b trial of psilocybin for treatment-resistant depression, suicidal ideation or self-injury was reported in all dose groups, including the near-placebo one.3 That reflects how ill the participants were going in, and it's exactly why medical psilocybin comes with monitoring and follow-up instead of a prescription and a pat on the back.
Dangerous behavior while impaired
Falls, accidents, and running from a frightening situation account for much of the real-world harm. In a survey of more than 9,000 mushroom users, 0.2% had sought emergency care, mostly for panic and paranoia, and the most common contributing factors were mindset, environment, and mixing substances.5
Lasting visual changes
A small share of people who use hallucinogens report visual disturbances that persist for weeks or longer, a condition called HPPD. It appears less common in controlled research settings than in recreational use.6 More in HPPD and shrooms.
What real-world data shows
The best look at psilocybin outside clinical trials comes from Oregon's licensed program. A 2026 study in JAMA Network Open followed 346 clients at 24 licensed service centers. Four people, 1.2%, had a severe behavioral reaction during their session. Meanwhile, 92% said they benefited, and rates of depression and anxiety dropped sharply by three months.4 That's a reasonable summary of the whole field: real risks, mostly manageable with screening and supervision, and substantial benefits for many people.
How legal programs reduce the risk
Licensed programs in Oregon and Colorado require an intake and preparation session before anyone takes psilocybin, where facilitators review health history, medications, and safety plans, and the session itself happens on-site with a trained facilitator present. If you're going to do this, that's the setting to do it in. Start with our psilocybin therapist finder.
Common questions
Can psilocybin cause schizophrenia?
There's no evidence psilocybin causes schizophrenia in people without a predisposition. In people with a personal or family history of psychotic disorders, it may trigger or unmask an episode, which is why clinical trials exclude them.
Can psilocybin make depression worse?
It can, for some people, at least temporarily. Difficult emotions can surface during and after a session. Trials have reported suicidal thoughts in some participants across all dose groups, which is why treatment happens with screening, monitoring, and follow-up care.
Is psilocybin safe for teenagers?
It hasn't been studied in teens, legal programs require clients to be 21 or older, and the developing brain is a reason for extra caution. The answer is no.
Sources
- Johnson MW, Richards WA, Griffiths RR. Human hallucinogen research: guidelines for safety. Journal of Psychopharmacology. 2008. doi.org/10.1177/0269881108093587
- Studerus E, et al. Acute, subacute and long-term subjective effects of psilocybin in healthy humans: a pooled analysis of experimental studies. Journal of Psychopharmacology. 2011. doi.org/10.1177/0269881110382466
- Goodwin GM, et al. Single-dose psilocybin for a treatment-resistant episode of major depression. New England Journal of Medicine. 2022. doi.org/10.1056/NEJMoa2206443
- Korthuis PT, et al. Safety and mental health outcomes of Oregon state-regulated psilocybin services. JAMA Network Open. 2026. doi.org/10.1001/jamanetworkopen.2026.30608
- Kopra EI, et al. Adverse experiences resulting in emergency medical treatment seeking following the use of magic mushrooms. Journal of Psychopharmacology. 2022. PMC9353971
- Doyle MA, et al. Hallucinogen persisting perceptual disorder: a scoping review covering frequency, risk factors, prevention and treatment. Expert Opinion on Drug Safety. 2022. doi.org/10.1080/14740338.2022.2063273
- Nayak SM, et al. Classic psychedelic coadministration with lithium, but not lamotrigine, is associated with seizures. Pharmacopsychiatry. 2021. doi.org/10.1055/a-1524-2794
This article is for education only and is not medical or legal advice. Psilocybin is a Schedule I substance under U.S. federal law. Talk with a licensed clinician before making decisions about your health. In a crisis, call or text 988.