Most psilocybin therapy trials use a single oral dose of 25 mg of synthetic psilocybin, taken in capsule form during a supervised session that lasts six to eight hours. This 25 mg fixed dose has become the standard across major clinical trials for depression, and it’s the dose moving through regulatory approval pipelines. But the full picture includes lower doses used as comparators, the reasoning behind the number, and how the overall treatment course is structured around that single capsule.
The Standard Therapeutic Dose
A 25 mg dose of synthetic psilocybin is the most widely studied therapeutic dose. A randomized clinical trial published in JAMA tested this amount against a placebo (100 mg of niacin, a B vitamin) in people with major depressive disorder. Each participant swallowed a single capsule with psychological support before, during, and after the experience. The study found the 25 mg dose was well tolerated and showed promise for treating depression.
Compass Pathways, the company furthest along in seeking regulatory approval, has tested three dose levels in its phase 2 trials: 25 mg, 10 mg, and 1 mg. The 1 mg dose functions essentially as a placebo, since it’s too low to produce meaningful psychological effects. The 10 mg dose serves as a moderate comparison point. But 25 mg is the target therapeutic dose, the one designed to produce a full psychedelic experience lasting roughly four to six hours.
Why Body Weight Doesn’t Change the Dose
Early psilocybin research used weight-adjusted dosing, typically expressed as milligrams per 70 kilograms of body weight. Researchers at Johns Hopkins analyzed data from ten studies covering 288 participants who received doses in the range of 20 to 30 mg/70 kg. They looked at whether body weight, sex, or other demographic factors changed the intensity of the experience or the therapeutic outcomes.
Across participants weighing anywhere from 49 to 113 kg (about 108 to 249 pounds), body weight had no significant effect on how strongly people responded to psilocybin. The same held true for sex. This means a 120-pound person and a 250-pound person can take the same 25 mg capsule and expect a comparable experience. The Johns Hopkins team concluded that the convenience and lower cost of a fixed dose outweigh any theoretical advantage of adjusting for weight. This finding simplified clinical protocols considerably and is one reason the flat 25 mg dose has become standard.
How This Compares to Mushrooms
The 25 mg used in clinical trials refers to pure, synthetic psilocybin, not dried mushrooms. This distinction matters because dried Psilocybe cubensis mushrooms, the most common species, contain a highly variable amount of psilocybin. Typical estimates range from about 6 to 10 mg of psilocybin per gram of dried material, but this fluctuates depending on the strain, growing conditions, and which part of the mushroom you’re measuring. A rough ballpark puts 25 mg of pure psilocybin somewhere in the range of 2.5 to 4 grams of dried cubensis mushrooms, though the precision of a synthetic capsule is impossible to replicate with natural material.
Oregon’s regulated psilocybin services, which launched in 2023, use whole psilocybin-producing mushrooms rather than synthetic capsules. The Oregon Health Authority set a maximum dose of 50 mg of psilocybin analyte per session. That ceiling is roughly double the standard clinical trial dose, giving facilitators room to work within a range while keeping an upper safety boundary in place.
Structure of a Full Treatment Course
Psilocybin therapy isn’t just the dosing session. The actual drug administration typically happens only once or twice across an entire treatment course. A typical protocol includes about six 60- to 90-minute talk therapy sessions spread across preparation and integration phases, with one or two dosing days in between. The dosing sessions themselves average about 7.5 hours, during which a trained therapist or facilitator stays present the entire time.
During preparation sessions, you work with a therapist to establish trust, set intentions, and learn what to expect from the experience. On dosing day, you take the capsule in a comfortable room, usually lying down with an eye mask and headphones playing a curated music playlist. The therapist provides reassurance and support but generally doesn’t direct the experience. In the days and weeks after, integration sessions help you process what came up and translate insights into lasting changes. Most trials space dosing sessions at least two to three weeks apart when a second dose is included.
Why Doses Below 25 mg Are Also Studied
The 10 mg dose used in some trials isn’t simply a “low dose” option for cautious patients. It plays a specific role in research design: helping scientists understand whether the full psychedelic experience is necessary for therapeutic benefit, or whether a milder effect might also work. At 10 mg, most people feel noticeable perceptual changes and emotional shifts, but the experience is considerably less intense than at 25 mg. Early results from dose-comparison trials suggest that 25 mg produces stronger and more durable antidepressant effects, though 10 mg is not inert.
The 1 mg dose, by contrast, produces no perceptible psychedelic effects at all. It exists purely as a research tool, a way to keep studies blinded so participants don’t know with certainty whether they received the active treatment. Traditional sugar-pill placebos don’t work well in psychedelic research because the effects are so obvious that participants immediately know which group they’re in.
Safety at Therapeutic Doses
Psilocybin has a wide margin between a therapeutic dose and a physically dangerous one. No deaths from psilocybin toxicity alone have been documented in clinical settings, and the lethal dose in animal studies is estimated to be hundreds of times higher than what’s used in therapy. The primary risks at 25 mg are psychological, not physical: transient anxiety, confusion, or distressing emotional experiences during the session. These are managed in real time by the therapist present in the room.
Common physical side effects include nausea, headache, and temporary increases in blood pressure and heart rate. These are generally mild and resolve within hours. People with a personal or family history of psychotic disorders are excluded from trials because psilocybin can trigger or worsen psychotic symptoms in vulnerable individuals. Cardiovascular screening is also standard, since the temporary blood pressure increase could pose a risk for people with certain heart conditions.