Psilocybin and Mental Health Risks: What the Large Studies Say

Clinical trials tell us what psilocybin does in a controlled room with screened volunteers and trained staff. They tell us much less about the real world, where people take mushrooms at home, at festivals and with friends. For that, researchers turn to large surveys and health records. These studies cannot prove cause and effect, but they cover hundreds of thousands of people, and together they give a fairly clear picture: for most adults, serious mental health harms appear to be uncommon, and for a minority with specific risk factors, they are real.

None of this is medical advice. If you have a mental health condition or take medication, talk to a health professional before considering psilocybin.

What the big surveys found

The United States runs a yearly National Survey on Drug Use and Health, and several research teams have used it to compare people who have used psychedelics with people who have not.

• In 2013, Teri Krebs and Pål-Ørjan Johansen analysed responses from more than 130,000 adults, about 22,000 of whom had used psychedelics. After accounting for other drug use, risk taking and traumatic experiences, they found no link between lifetime use of psilocybin, LSD or mescaline and serious psychological distress, mental health treatment or symptoms of psychiatric disorders. In some cases, psychedelic use was linked with lower rates of problems.
• In 2015, Peter Hendricks and colleagues looked at more than 190,000 adults. Lifetime use of classic psychedelics was associated with lower odds of psychological distress in the past month, and of suicidal thoughts, plans and attempts in the past year. Use of other illegal drugs was associated with higher odds of the same problems.

These findings are reassuring, but read them carefully. They show associations, not causes. People who choose to take psychedelics may differ from those who don't in ways surveys can't measure, and people who had a bad reaction may be less likely to keep using or to answer surveys.

How often do things go badly wrong?

The Global Drug Survey asked more than 9,000 people who had used magic mushrooms in the past year whether they had needed emergency medical treatment as a result, in a study published in 2022. Nineteen people, about 0.2 per cent, said yes. Anxiety, panic and paranoia were the most common symptoms. All but one were back to normal within 24 hours. The factors people blamed most were a poor mindset, a poor setting and mixing with other substances, and younger users were at higher risk.

That fits earlier work. A 2011 review for the Dutch government rated the harm potential of magic mushrooms as low, with panic, risky behaviour in the wrong setting and mixing with alcohol as the main concerns. And in a Johns Hopkins survey of nearly 2,000 people about their single most difficult mushroom experience, 84 per cent said they had benefited from it in some way, yet about 11 per cent said they had put themselves or others at risk of physical harm during it. Among those whose difficult experience was more than a year in the past, 7.6 per cent had sought treatment for lasting psychological symptoms.

Psychosis and bipolar disorder: the real red flags

The risks researchers take most seriously involve psychosis and mania.

• A study published in JAMA Psychiatry used Ontario health records for more than 9 million people. Those who went to an emergency department because of hallucinogen use were far more likely to be diagnosed with a schizophrenia spectrum disorder within three years than the general population. After accounting for other substance use and mental health conditions, the risk was still about 3.5 times higher. The study cannot show that hallucinogens caused the diagnoses, and it only looked at people whose use ended in an emergency visit, but it is an important Canadian warning sign.
• A 2024 study of more than 16,000 Swedish twins, also in JAMA Psychiatry, found that teenage psychedelic use was linked with fewer psychotic symptoms overall. But among those with a higher genetic risk for bipolar disorder or schizophrenia, psychedelic use was associated with more manic symptoms.

This is why clinical trials screen out people with a personal or family history of psychosis or bipolar disorder. If that describes you, the safest choice is to avoid psilocybin altogether.

Other risks worth knowing

• Medication interactions. Lithium combined with psychedelics has been linked to seizures, and other drugs, including MAOIs, tramadol and some antidepressants, either interact or blunt the effects. Our guide to psilocybin and medications explains which ones.
• Difficult experiences. Even in trials, fear, anxiety and confusion during the session are common. In a 2022 trial of 233 people with treatment-resistant depression, a small number had suicidal thoughts or self-harm in the weeks after, which is why trials monitor participants closely.
• Heart and blood pressure. Psilocybin raises blood pressure and heart rate during the experience, which matters for anyone with a heart condition.
• Age. Both the Global Drug Survey and the Swedish twin study point to younger people being more vulnerable.

Who should be most careful

• Anyone with a personal or family history of psychosis, schizophrenia or bipolar disorder
• Anyone taking lithium, MAOIs, tramadol, antidepressants or other psychiatric medication without medical advice
• Anyone with a heart condition or high blood pressure
• Anyone in a mental health crisis or at risk of suicide
• Anyone under 19 (you must be 19 or older to shop with us)

How people lower the risks

The emergency survey's list of what went wrong, a poor mindset, a poor setting and mixing substances, doubles as a list of what to get right. Start low, using our guide to dose sizes. Plan your set and setting. Have a sober trip sitter for any larger amount. Avoid mixing with alcohol or other drugs. And know what to do if things get hard: our guide to handling a challenging trip walks you through it.

If you need help

If you or someone you're with is in danger, call 911. If you are thinking about suicide or are in crisis, call or text 9-8-8 at any time. For anything else, talk to a doctor: they have heard it before and are there to help, not to judge.

Sources

• Krebs and Johansen (2013), Psychedelics and mental health: a population study, PLOS ONE
• Hendricks et al. (2015), Classic psychedelic use is associated with reduced psychological distress and suicidality in the United States adult population, Journal of Psychopharmacology
• Kopra et al. (2022), Adverse experiences resulting in emergency medical treatment seeking following the use of magic mushrooms, Journal of Psychopharmacology
• van Amsterdam, Opperhuizen and van den Brink (2011), Harm potential of magic mushroom use: a review, Regulatory Toxicology and Pharmacology
• Carbonaro et al. (2016), Survey study of challenging experiences after ingesting psilocybin mushrooms, Journal of Psychopharmacology
• Myran et al. (2025), Emergency department visits involving hallucinogen use and risk of schizophrenia spectrum disorder, JAMA Psychiatry
• Simonsson et al. (2024), Adolescent psychedelic use and psychotic or manic symptoms, JAMA Psychiatry
• Goodwin et al. (2022), Single-dose psilocybin for a treatment-resistant episode of major depression, New England Journal of Medicine

This guide is general information, not medical or legal advice. If you have health questions, talk to a health professional.