The most widely followed psilocybin microdosing schedule is one dose every three days: one day on, two days off. This three-day cycle, popularized by psychedelic researcher James Fadiman, is built around the idea that each microdose produces a residual effect lasting one to two days after the dosing day itself. Other schedules exist, but nearly all share the same core principle: rest days between doses to prevent tolerance.
The Fadiman Protocol
The Fadiman protocol is the most referenced microdosing schedule in both popular press and research literature. It works like this: you take a microdose on Day 1, take nothing on Day 2 and Day 3, then dose again on Day 4. This creates a repeating three-day cycle where you dose roughly twice per week.
The two rest days serve a specific biological purpose. Psilocybin works primarily by binding to serotonin receptors in the brain. When those receptors are stimulated repeatedly, they become less responsive. Animal research on closely related compounds shows that just four doses within 24 hours can reduce receptor activity by as much as 70%, and once those receptors downregulate, they take roughly three to five days to recover to normal levels. Spacing doses three days apart helps keep the receptors responsive so each dose has a similar effect.
The rest days also function as a built-in comparison. Day 2 lets you notice any lingering effects from the dose. Day 3, with no residual influence, gives you a baseline to compare against. This makes it easier to judge whether the microdose is actually doing anything.
The Stamets Protocol
Mycologist Paul Stamets proposed a different pattern: four days on followed by three days off. This schedule packs more dosing days into each week but includes a longer rest window. Stamets also recommended combining the psilocybin microdose with lion’s mane mushroom and niacin (vitamin B3), a combination he called a “stack” that he suggested could support nerve growth. This protocol has a following in microdosing communities, though the stacking supplements haven’t been validated in controlled trials.
How Long a Cycle Should Last
Most microdosing guides recommend running a cycle for four to eight weeks, then taking a break of two to four weeks before starting again. This reset period serves two purposes: it gives your serotonin receptors a full recovery window, and it creates a longer comparison period where you can evaluate whether microdosing made a meaningful difference in your daily life. Without a break, it becomes difficult to distinguish genuine effects from habit or expectation.
There’s no established consensus on exactly how many cycles you can run in a year. The general principle is that microdosing is treated as a periodic practice with clear start and stop dates rather than a continuous daily supplement.
What Counts as a Microdose
A microdose of psilocybin mushrooms typically falls between 0.1 and 0.5 grams of dried material. The dose is meant to be sub-perceptual, meaning you shouldn’t feel “high” or experience visual changes. If you notice obvious psychoactive effects, the dose is too high. Most people start at the low end (0.1 g) and adjust upward only if they feel nothing at all over several doses. Potency varies significantly between mushroom species and even between batches, so a dose that was sub-perceptual last month could feel stronger with a new batch.
Best Time of Day to Dose
Morning dosing is the standard recommendation, and research on psilocybin’s effects on sleep supports this. In a controlled study, participants who received psilocybin capsules around 9 a.m. showed no significant changes in total sleep time, sleep efficiency, or subjective sleep quality that night. There was a modest increase in the time it took to enter REM sleep and participants perceived falling asleep as taking about 10 minutes longer on average. These are minor effects for a morning dose. Taking a microdose later in the day, particularly in the afternoon or evening, could amplify those sleep-onset effects, which is why most protocols specify morning timing.
What the Placebo Research Shows
The dosing schedules above are based on community practice and pharmacological reasoning, not on clinical evidence that microdosing works as advertised. This is worth knowing as you plan your schedule. Two recent double-blind, placebo-controlled trials found that psilocybin microdoses did not significantly improve attention, mood, cognitive control, or self-reported well-being compared to placebo. A separate self-blinding study initially found improvements in well-being and mindfulness, but those effects disappeared entirely once researchers accounted for participants’ expectations about whether they’d received a real dose.
In a crossover study using 0.5 grams of dried mushrooms (the upper end of the microdose range), participants reported noticeable subjective effects, but their performance on tests of working memory, executive function, and creative thinking didn’t improve. In fact, accuracy on some tasks slightly decreased. The most consistent finding across studies is that people who believe they’re microdosing tend to report feeling better, regardless of whether they received psilocybin or a placebo.
Interactions With Antidepressants
If you take an SSRI or SNRI antidepressant, psilocybin’s effects are substantially blunted. In a large survey analysis, about 47% of people taking SSRIs and 55% of those on SNRIs reported weaker-than-expected effects from psilocybin mushrooms. This dampening effect persists well beyond the last pill. Even three to six months after discontinuing an SSRI or SNRI, the probability of reduced psilocybin effects remained significantly elevated compared to people who’d never taken these medications. This isn’t a reason to stop your antidepressant, but it’s relevant context if you’re wondering why a microdose schedule isn’t producing the effects you’ve read about.
A Potential Heart Valve Concern
One safety consideration that rarely appears in popular microdosing guides involves the heart. Psilocybin’s active form in the body, psilocin, binds to a serotonin receptor subtype found on heart valve tissue. Chronic stimulation of this receptor is the established mechanism behind drug-induced heart valve disease caused by medications like fenfluramine (the withdrawn diet drug) and certain migraine treatments. Psilocin binds to this receptor with even greater affinity than it does to the receptor responsible for its psychoactive effects, and lab assays suggest it’s roughly as potent at this receptor as several drugs known to cause valve problems.
No cases of heart valve disease from psilocybin microdosing have been documented, and researchers note that the structural similarities don’t automatically mean the risk is the same. But the concern is biologically plausible enough that it has been flagged in peer-reviewed literature, particularly for people who microdose continuously over many months. This is another reason why cycling on and off, rather than dosing indefinitely, is the standard approach.