Psilocybin (4-phosphoryloxy-N,N-dimethyltryptamine) comes from certain types of mushrooms found on nearly every continent. The mushrooms, which are also known as shrooms or magic mushrooms, are typically consumed dried or powdered. Psilocybin is part of a group of drugs called psychedelics—or hallucinogens—that have the potential to change a person’s sense of reality, leading them to see, hear, and feel things that are not happening in real life, or to experience reality in a different way.
The mushrooms have a long history of use. There is evidence that indigenous people in Central America used them for healing and spiritual rituals as far back as 3000 B.C. Scientists began studying psilocybin decades ago, along with related substances like lysergic acid diethylamide (LSD), to examine their potential to treat mental illness, including substance use disorders.
Now, there is a new surge of interest in discovering how psilocybin works and its potential to help treat conditions such as depression, post-traumatic stress disorder (PTSD), addiction, pain, and neurodegenerative disorders. Individuals are also curious to see how psilocybin might affect their way of thinking and living. According to a survey published in 2021 of more than 7,000 people, some 7%—or about 500 people—reported having used psilocybin mushrooms in the past year. People who use them may hope to have fun, to improve their well-being, or to self-treat a medical disorder such as depression or anxiety.
For more information, see Psychedelic and Dissociative Drugs.
When a person takes psilocybin, their body converts it to another substance, psilocin. Psilocin attaches to and activates receptors, or binding sites, for the brain chemical serotonin, primarily the serotonin 5-hydroxytryptamine 2A (5HT2a) receptor. Researchers think this action is responsible for much of a person’s subjective experience when they take the mushrooms.
The substance also affects how the brain works and how different brain regions communicate with each other. These altered patterns of brain activity contribute to a person’s profound change in consciousness. Some regions increase in activity and connectedness while others decrease. Studies suggest that psilocybin can temporarily disrupt communication among regions of the brain known as the default mode network, which is most active when we self-reflect. Reducing a person’s sense of self-awareness may lead to a greater feeling of openness and increased connectedness to the world.
Psilocybin has a wide range of potential effects. A person’s personality and expectations of the experience at the time they take the drug—called the “set”—and the surrounding people and environment—called the “setting”—play a role in how they respond to it. Also important are the amount taken and potency (concentration and strength), as well as a person’s age, unique biology, sex, personality, and history of drug use. Effects may include:
Altered Perception
Magic mushrooms typically cause shifts in how a person perceives reality. People may see colors, shapes, or scenes; hear things that aren’t real; or lose their sense of time and space.
Mood and Perception Changes
A person taking psilocybin may have what’s called a mystical experience, where they enter a dreamlike, euphoric state, perhaps having visions or reliving memories. They may have a different sense of self, feeling that they have no personal boundaries and are one with the universe – what some researchers call “oceanic self-boundlessness”. This experience can be blissful, but it may also be frightening, and cause fear or panic.
Physical Effects
Psilocybin can cause many effects, some of them unpleasant. See “Is Psilocybin Safe?” for more information.
People have been using mushrooms that contain psilocybin for thousands of years. Researchers theorize that the substance was used to bring about a mystical state during rituals. Today, people use the mushrooms in the hopes of having a unique, interesting, enlightening, and/or spiritual experience. Others take very small amounts of the substance regularly, a practice called microdosing, trying to improve their mental state and productivity. Researchers are testing psilocybin’s potential to ease mental health disorders like substance use disorders, depression, anxiety, and obsessive-compulsive disorder, and some people report taking magic mushrooms on their own hoping to achieve the same results, though additional research is needed to support this outcome.
Psilocybin has a low level of toxicity, which means that it has a low potential of causing potentially fatal events like breathing problems or a heart attack. However, studies show there are health risks associated with taking psilocybin, particularly when unsupervised and outside of a research study and clinical supervision. These include:
Dangerous Behavior
People may do higher-risk things after taking mushrooms in an unsupervised environment—driving dangerously or walking in traffic, for example—as they may be less aware of their physical surroundings and have an impairment in their ability to think clearly.
Physical Side Effects
Psilocybin typically raises blood pressure and heart rate, which may be dangerous for people with heart conditions. People may also experience side effects like agitation, confusion, vomiting or nausea, which may be severe and require medical attention. There is also the risk of misidentifying mushrooms and taking a toxic mushroom instead of psilocybin.
Fear
Some people who take magic mushrooms have extreme fear, anxiety, panic, or paranoia as they experience its hallucinogenic effects, which is known as a “bad trip.”
Mental Health Issues
The risk of mental health problems such as psychosis or suicidality in supervised clinical settings among people who participate in research on psilocybin is low. However, poor mental health outcomes may be more likely outside of clinical use. For more information, see “What is the Relationship Between Psychedelic and Dissociative Drugs and Mental Illness?”
Hallucinogen Persisting Perception Disorder (HPPD)
More commonly called flashbacks, HPPD is when people experience the same images or scenes they saw when they were under the influence of a substance. Flashbacks can be brief, or they can reoccur for years after an experience with a substance. Studies suggest flashback episodes are rare and when they do occur are not always a negative experience.
For more information, see “Are psychedelic and dissociative drugs safe?”
Research to date suggests that use of psilocybin does not typically lead to addiction. To be diagnosed with a substance use disorder, a person must meet specific diagnostic criteria for continued substance use despite negative consequences. The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5)—a reference text professionals use to diagnose substance use disorders and other psychiatric disorders—does not include substance use criteria specifically related to psilocybin, though it includes diagnoses of phencyclidine (PCP) use disorder and “other hallucinogen use disorder”. For more information, see “Are psychedelic and dissociative drugs addictive?”
There is no data on the safety of taking psilocybin during pregnancy, for either a mother or a developing baby. People should consult their health provider before taking any drug during pregnancy.
Microdosing means regularly taking a very small amount of a hallucinogenic substance, typically 5-10% of a standard dose. Some people microdose psilocybin in the hopes that it will improve mental health issues like depression, anxiety, and obsessive-compulsive disorder (OCD). Though some people claim psilocybin has improved their symptoms, research to date has not established that microdosing is safe or effective.
Researchers are investigating psilocybin as a potential treatment for many health disorders. These include:
Substance Use Disorders
Preliminary research indicates that psilocybin may be helpful in treating substance use disorders, including tobacco use disorder. NIDA is funding a large, multi-site study on the effectiveness of psilocybin versus a nicotine patch, in combination with therapy, to help people stop smoking.
Depression and Anxiety
There is evidence that psilocybin may be an effective treatment for depression and anxiety disorders. To support further research, the FDA granted “Breakthrough Therapy” designation for two formulations of psilocybin being studied for safety and efficacy as a medical treatment for depression.
Anxiety Related to Illness and End-of-Life
Research suggests that some psychedelics can reduce anxiety and depression in people with cancer, and can promote well-being, quality of life, and acceptance of their illness and related issues. The National Cancer Institute, part of the National Institutes of Health, is funding a follow-up multi-site clinical trial to investigate the use of psilocybin to treat cancer-related mental health issues.
For more information on psilocybin and psychedelic or dissociative drugs as potential therapeutic substances, see, “Psychedelic and dissociative drugs as medicines.”
NIDA is conducting and supporting preclinical (laboratory) research into psilocybin’s effects on the brain and body, and whether there are similar substances that may have the same benefits without side-effects such as hallucinations. The institute also supports clinical investigations into psilocybin as a therapeutic substance. These include studies on its effectiveness and safety as a treatment for substance use disorders and to help people quit smoking.
Find out more about NIDA-supported studies related to psilocybin.
