What is psilocybin used for? Psilocybin, a chemical found naturally in certain mushrooms, is used for various mental health problems. However, its benefits are not well defined. If you are having symptoms of a mental health problem, do not try to treat these symptoms on your own. Talk to your health care provider about your treatment options. If you are already taking a medicine for a mental health problem, talk to your health care provider before starting psilocybin. Psilocybin may interact with some medicines. Note: Psilocybin is not approved by the FDA for any use. The FDA also does not consider psilocybin to be a legal dietary ingredient in the U.S. It is a Schedule I controlled substance, which means that it does not have an acceptable medical use and has a high risk for misuse. Learn more about the regulation of psilocybin here. How does psilocybin work (mechanism of action)? Psilocybin is a chemical found in psilocybe mushrooms. These mushrooms are commonly known as magic mushrooms because they act as psychedelics, which means that they can affect the mind and cause hallucinations. Psilocybin causes most of these psychedelic effects. Your body changes psilocybin into another chemical called psilocin. Psilocin can bind to certain receptors in your brain, changing the way you experience the world around you. This can cause a “psychedelic trip,” which can involve hallucinations, reliving old memories, or being in a dream-like state. There is growing interest in using psilocybin to help manage certain mental health problems, such as anxiety, depression, posttraumatic stress disorder (PTSD), and substance use disorders. But the benefits of psilocybin are not well defined. The dream-like experiences and hallucinations that occur with larger doses of psilocybin may be pleasant for some people and frightening for others. Your experience can depend on your own personal history, as well as the environment around you while you are using psilocybin. In most research studies, psilocybin is given in a health care facility in the presence of a trained professional who will be with you through the entire day. In some cases, this person will help to talk you through your feelings and hallucinations so that you are less likely to have a frightening, paranoid, or panicked experience. Although the best way to guide someone through the use of psilocybin is unclear, this type of assistance may reduce your risk of having a “bad trip” while using psilocybin. When most people think of psilocybin and other psychedelics, they think of the large doses that can cause a “psychedelic trip.” But very small doses (microdoses) of psilocybin usually do not cause psychedelic effects. These “microdoses” are usually less than one-tenth of the dose that would cause a psychedelic trip. Some people have proposed that taking regular microdoses of psilocybin, such as every day or every other day, may help with certain mental health problems. But the benefits and risks of microdoses are poorly studied and not well defined. Pure psilocybin is removed from mushrooms so that it can be given in controlled doses (usually as part of a research study). This is very different from taking magic mushrooms, which naturally contain many different chemicals in different amounts. Some other chemicals in magic mushrooms may have effects on the body and brain. These effects will vary depending on how much of each chemical, including psilocybin, is found in the specific batch of mushrooms you are taking. How should I store psilocybin? Psilocybin should be stored according to the product label. If you will store psilocybin at home, follow the instructions given by your health care provider. Side Effects What are the most common side effects of psilocybin? The most common side effects of psilocybin are listed below. These side effects may vary depending on the dose you are taking and whether you are taking pure psilocybin (usually as part of a research study) or mushrooms that contain psilocybin. Tell your health care provider if you have any of these side effects that bother you. Hallucinations (see below) Fast heartbeat Increased blood pressure Muscle weakness or twitching Nausea or vomiting Paranoia or fear Trouble with balance or coordination There may be other side effects of psilocybin that are not listed here. Contact your health care provider if you think you are having a side effect. In the U.S., you can report side effects to the FDA at www.safetyreporting.hhs.gov or by calling 888-SAFEFOOD (888-723-3366). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.