Even at high doses, and despite its power, psilocybin has little direct physical effect on the body, and no known long-term physical effects. It doesn’t suppress breathing like too much alcohol does, or poison cells like tobacco. The effects are mostly on the user’s consciousness. Some people feel something similar to motion-sickness at the start, which usually passes.
However, research shows that people’s blood pressure and sometimes heart rate can increase during the experience, and it affects blood flow around the brain, which can cause brief headaches for a proportion of users after the trip. A psychedelic experience can also be comparable in impact to some of the most meaningful experiences available in life, such as the birth of a child, a memorial service, or a pilgrimage to a holy site, all of which can occasionally do harm as well as good to our bodies, minds and lives.
For people who are comfortable with the cardiovascular effects of exercise, or of those major life experiences of comparable emotional magnitude, the effects associated with psilocybin are “no cause for concern”. Naturally, those people who would be at high risk from exercise or major life events, due to pre-existing conditions or frailty, could also be at risk from psilocybin. For example, one person with a transplanted heart (which cannot receive the normal signals that regulate heart rate) has died after taking psilocybin.
Whilst psilocybin is generally considered safe to the body, over the decades a small number of people have been hurt or have died after consuming it, in incidents such as car crashes, drownings and falls. Like drink-driving deaths, these tragedies are largely preventable. This kind of risk is a compelling argument for taking a known quantity of a psychedelic in a supportive setting like a retreat.
All our facilitators are qualified in first aid to safeguard participants during the psychedelic experience and at all times. None of the nearly 900 participants we attended our retreats have reported any lasting physical harm.
Studies have looked for lasting effects on mental health and wellbeing in psychedelic users in different contexts, from the least to the most supportive environments. Compared to the population as a whole, users of psilocybin in America are significantly less likely to require inpatient care or medication for mental health problems than non-users. So psilocybin seems at least as likely to benefit than to damage mental health.
Because psychedelics alter our consciousness so significantly, a safe and supportive environment is crucial. Our model for psychedelic facilitation owes something to both the developing Western therapeutic model, and to communal ritual settings. Studies have shown that psychedelic use in both of these supportive contexts benefit mental wellbeing on average, reducing rather than increasing the risk of an individual suffering an episode of psychopathology.