Effects of psilocybin generally resemble a shorter LSD trip. See psilocybe cubensis.
Effects often begin 45 minutes after ingestion and last from 4-5 hours. At low doses, hallucinatory effects occur, including walls that seem to breathe, a vivid enhancement of colors and the animation of organic shapes. At higher doses, experiences tend to be less social and more entheogenic, often catalyzing intense spiritual experiences.
The effects are often pleasant, even ecstatic, including a deep sense of connection to others (especially those also participating with the drug), and a general feeling of connection to nature and the universe. However, as with all psychedlic chemicals, not all experiences are positive. This is especially true when they are taken with other drugs, in huge doses, during times of mental instability, or by people with psychoemotional problems. In such situations, "bad trips" are much more likely to occur. Anxiety, frightening hallucinations, confronting (symbolically or literally) past or deep-seated internal conflicts, and feelings of permanent disconnection from reality and the Self can be quite intense and cause panic. The possibility of such experiences can be mitigated by being cognizant of one's "set and setting."
Experimentation with psychedelics should be done with a lot of information and significant discretion.
Psilocybin has been studied as a treatment to several disorders.
In the US, an FDA-approved study began in 2001 to study the effects of psilocybin on patients with obsessive-compulsive disorder.
Psilocybin and psilocybin mushrooms are DEA Schedule 1, making them illegal to possess under federal law. (Researchers and their subjects are granted exemptions by the DEA.)
Under state law, it is illegal to possess psilocybin and psilocybin mushrooms in all states except Florida, where a court decision ruled that wild psilocybin mushrooms themselves are not illegal to possess.