Psilocybin mushrooms have very low toxicity, making physical harm and death through overdose extremely unlikely. Mushrooms are also not associated with lasting mental health damage. However, taking too much can increase the likelihood of a bad trip, which can be psychologically challenging while it lasts and, in a tiny minority of cases, lead to self-harm.
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Can you die from taking too many shrooms?
Since the backlash against the hippie movement in the 1960s, psychedelic mushrooms have been portrayed in the media as extremely dangerous, leaving users at risk of self-harm, psychosis, and death.
In reality, the 2016 Global Drug survey found that psilocybin mushrooms are the safest recreational drug. Of 12,000 people who reported using magic mushrooms, just 0.2% sought emergency medical attention, at least five times less than the rate for cocaine, LSD, and MDMA.
Among people who did seek medical attention after using magic mushrooms, the most commonly occurring symptoms were anxiety and panic (68%), paranoia and suspiciousness (68%), and seeing and hearing things (42%)—all symptoms of a bad trip or the expected psychedelic effects of psilocybin. No emergency room visits led to death or lasting harm, and all but one patient recovered within 24 hours.
Psilocybin has low toxicity, and the psilocybin concentration in mushrooms is low—usually, 10-12mg per 1g of Psilocybe cubensis mushrooms—making overdose extremely unlikely.
And despite urban legends and a few sensationally reported cases, psychedelic-induced suicide is also very uncommon.
However, people with underlying health conditions and who take psilocybin mushrooms alongside other substances may be more susceptible to adverse effects.
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The toxicity of psilocybin is very low, with the lethal dose estimated at 1000 times the psychoactive dose. In contrast, the lethal dose of intravenous heroin is just five times the effective dose.
In humans, even high doses capable of inducing psychosis (30mg per 70kg of body weight) only slightly and transiently affect heart rate and blood pressure.
However, whether psilocybin mushrooms can cause physiological damage to the human body is a contentious topic among scientists. One review highlighted a few cases of cardiovascular and cerebral damage attributed to psilocybin. However, other scientists noted that those cases all involved the consumption of fungi, and users could have accidentally ingested more toxic mushrooms. Other surveys of the medical literature insist that as a class, hallucinogens have not been shown to cause organ damage or neuropsychological harm.
When psilocybin is administered itself, as it is in therapeutic use, negative effects are very minimal. In the largest controlled study of psilocybin safety, conducted by King’s College London, subjects experienced no serious adverse effects.
Read here to learn more about the effects of shrooms and how long they stay in your system.
Users sometimes report psilocybin overdoses, but they usually mean very intense trips, experiences in which they didn’t just experience the synesthesia of lower doses but experienced full-fledged, and sometimes terrifying, hallucinations, and ego death.
Overdoses with physiological consequences are extremely rare. In scientific literature, just two deaths have been attributed to psilocybin overdoses alone with no concomitant use of other drugs. However, scientists have cast doubt on both reports and suggest that other factors may have contributed to the deaths.
The lethal dose of psilocybin in humans isn’t known. The median lethal dose in rats is 280mg per kilogram of body mass, one and a half times the lethal dose of caffeine. For a 60 kg (130 lb) human to reach that concentration, they’d have to consume 37 lb of fresh mushrooms or 3.7 lb of dried mushrooms. Given the vomiting and nausea psilocybin mushrooms induce, that’s likely a physiologically impossible feat.
Additional health concerns
Self-harm and suicide
Most reported deaths associated with psilocybin mushrooms involve people in the grips of bad trips harming themselves. A classic case is the mushroom user who jumps out a window because they believe they can fly.
While these cases draw sensationalized headlines, experts believe they are exceedingly rare. One report looks at the Netherlands, where hundreds of thousands of doses of magic mushrooms are legally sold each year. However, according to data from the European Monitoring Center for Drugs and Drug Addiction (EMCDDA) and Dutch health authorities, serious injuries are very rare.
Lasting psychological effects
Psychedelics are also anecdotally associated with psychotic breaks and lasting psychological damage—the urban legend of the tripper locked away because he believed he was a glass of orange juice. However, population-level studies suggest that lifetime psychedelic use isn’t associated with serious mental health problems. In fact, the reverse may be true.
In one survey of nearly 200,000 people, those who in the past had used classic psychedelics, including mushrooms, were 19% less likely to have been in psychological distress in the previous month than people who hadn’t used psychedelics. They were also 14% less likely to have had suicidal thoughts in the past year and 36% less likely to have attempted suicide over the same period. This reflects the benefit that people with depression felt for up to a year after two doses of psilocybin and the promising research into other psychedelics as a treatment for a range of mental health conditions.
However, psychedelics can worsen symptoms in people with pre-existing psychotic disorders, including schizophrenia and bipolar disorder, and may accelerate the onset in young people predisposed to them.
Other toxic mushrooms
Psilocybin mushrooms may look similar to mushrooms that are poisonous to humans. Inexperienced foragers could mistake them.
There’s speculation that some of the adverse experiences people have reported could actually be attributed to other drugs lacing the mushrooms or substituted for them. Reports suggest that some “magic mushrooms” consumers buy on the black market are really store-bought mushrooms sprinkled with PCP or other, riskier drugs. 
The few deaths caused by psilocybin use, either through overdose or self-harm, involve other substances: typically, alcohol. Read here to find out more about taking magic mushrooms with other substances
What to do if you have a bad shrooms trip
Bad trips can be terrifying. Although they always subside, psilocybin’s distortion of time can make them feel interminable.
If you do experience a bad trip, you should:
Get to a safe, non-stimulating, and comfortable environment, away from hazards such as heights and bodies of water and anything that might contribute to sensory overload, such as crowds, bright lights, and noise.
Remain under the watch of a sober person. If you took mushrooms without a trip sitter, reach out to a trusted friend or family member.
Don’t try to control the experience—surrender to it.
Try to relax and meditate.
Play calming music.
Don’t self-medicate by taking another substance. Most adverse events with psilocybin involve an additional drug, most commonly alcohol.
Don’t be afraid to seek medical attention if you’re having serious mental health symptoms such as psychosis.
Helping someone else having a bad trip
If you’re helping someone who is having a bad experience on shrooms, you should:
Get them to a safe, quiet environment.
Ask for permission before touching them.
Offer them blankets and water.
If they start acting irrationally or posing a threat to themselves or anyone else, you should seek appropriate help, including emergency medical treatment.