The Fadiman protocol — usually written 1/3/1 — is the reference schedule of microdosing: dose on day one, rest on days two and three, dose again on day four, and repeat. The two rest days are the point. They are meant to limit the rapid tolerance the serotonin system develops to psychedelics, and to leave non-dose days a person can compare against their dose days. The schedule is named for James Fadiman, whose correspondence-and-diary work with more than a thousand people is the largest descriptive dataset behind any microdosing schedule. That is precisely the trap: a very large body of self-reports is still a body of self-reports. The protocol is the best-documented schedule, not a proven one — there has been no controlled trial of the schedule itself, and the strongest controlled microdosing study found benefits appearing under placebo as well as active dose.
The schedule, plainly
The Fadiman protocol runs on a four-day repeating cycle. Day one is a dose day. Days two and three are rest days — no dose. Day four is a dose day again, which starts the next cycle. In practice this places dose days on day one, day four, day seven, day ten, and so on, with two clear days between each. The “1/3/1” shorthand is a way of describing one dose day sitting inside a roughly three-day rhythm; people also describe the same pattern as “one day on, two days off.” Whichever label is used, the rhythm is identical, and the numbers refer to the pattern of dose and rest days, not to any quantity taken.
What the schedule does not specify is the dose. Finding a sub-perceptual amount is a separate problem, handled by titration rather than by the calendar, and it is covered in finding your dose. The Fadiman protocol is a rule about timing; the dose is a rule about amount, and the two are chosen independently.
The rationale: tolerance and contrast
Two ideas justify the rest days, and it is worth being precise that they are justifications, not results.
The first is tolerance. Classic psychedelics act mainly through the serotonin 5-HT2A receptor, and that receptor system develops tolerance unusually quickly — the response to a repeated dose falls off fast, a pattern long described for psychedelics and sometimes called tachyphylaxis. [1] Peer-reviewed Psychedelics doi:10.1124/pr.115.011478 If a person dosed every day, the expectation from this pharmacology is that the effect would diminish and the receptor system would stay in a continuously adapted, downregulated state. Spacing doses with rest days is the practical response: enough gap to avoid continuous engagement. The receptor biology behind this is set out in the 5-HT2A mechanism article, and the rest-day logic in full in tolerance and cycling.
The second is contrast. A person microdosing has no placebo and no blind. Their only available comparison is between their own dose days and their own non-dose days. By interleaving the two, the 1/3/1 schedule produces a within-person contrast a self-tracker can read. This is genuinely the logic Fadiman’s own reporting leaned on — daily ratings across dose and non-dose days. [2] Observational Might Microdosing Psychedelics Be Safe and Beneficial? An Initial Exploration doi:10.1080/02791072.2019.1593561 It is also, unavoidably, the contrast most exposed to expectation: people generally know which days are dose days and expect those days to feel different, which is the central reason self-report on a known schedule is weak evidence. [3] Clinical trial Self-blinding citizen science to explore psychedelic microdosing doi:10.7554/eLife.62878
What actually documents it
Here the honest accounting matters more than anywhere else in the cluster, because the Fadiman protocol’s reputation rests entirely on volume of observation.
Fadiman and Korb’s published account describes a systematic exploration built from hundreds of lengthy self-reports, and a follow-on phase in which more than a thousand people across dozens of countries completed daily mood ratings — using a standard positive-and-negative-affect checklist — for periods ranging from about a week to several months. [2] Observational Might Microdosing Psychedelics Be Safe and Beneficial? An Initial Exploration doi:10.1080/02791072.2019.1593561 Participants reported improvements in low mood and increases in energy and effectiveness. Survey work since then confirms that schedules of this kind, and the broader practice, are widespread, and characterizes the doses and rhythms people actually use. [4] Observational Adults who microdose psychedelics report health related motivations and lower levels of anxiety and depression compared to non-microdosers doi:10.1038/s41598-021-01811-4 This is a substantial descriptive record, and it is the reason the schedule is the field’s default.
But every part of that record is observational and uncontrolled. There was no placebo group, no blinding, and no randomization; participants chose to microdose, chose the schedule, and knew they were dosing. That design cannot separate a drug effect from expectation. The point is not hypothetical. A systematic observational study that tracked microdosers and also measured their beliefs found that people expected large, wide-ranging benefits, that the actual reported outcomes were more limited, and that the effects people most expected were not the ones that showed up — a signature of expectancy shaping reports. [5] Observational A systematic study of microdosing psychedelics doi:10.1371/journal.pone.0211023 And when the practice has been put under a self-blinding, placebo-controlled design, benefits appeared under placebo as well as active dose. [3] Clinical trial Self-blinding citizen science to explore psychedelic microdosing doi:10.7554/eLife.62878 Systematic reviews reach the same conclusion: placebo-controlled evidence of effects beyond expectation remains limited. [6] Systematic review Is microdosing a placebo? A rapid review of low-dose LSD and psilocybin research doi:10.1177/02698811241254831
So the schedule is documented — extensively — and unproven. Crucially, none of the observational record compares the Fadiman protocol against any other schedule; there is no head-to-head trial that would license calling it the most effective rather than the most described. [7] Peer-reviewed Microdosing psychedelics: More questions than answers? An overview and suggestions for future research doi:10.1177/0269881119857204
Reading the “since the 1960s” framing
Popular accounts sometimes describe the Fadiman protocol as documented “since the 1960s.” It is worth disentangling. Interest in low doses of psychedelics goes back decades, and Fadiman’s own engagement with the subject is long-standing. But the systematic collection of microdosing self-reports under this schedule is a far more recent project, with the published account appearing in 2019. [2] Observational Might Microdosing Psychedelics Be Safe and Beneficial? An Initial Exploration doi:10.1080/02791072.2019.1593561 The depth of the observational record is real; reading it as decades of rigorous study would not be accurate.
Origin does not equal validation. It is worth holding these apart as a general matter: a framework’s influence and the evidence behind it are separate questions. The Fadiman schedule became the field’s reference point because it offered structure and a way to observe change over time, and because one researcher documented it at scale — not because a study showed it outperforms the alternatives. [7] Peer-reviewed Microdosing psychedelics: More questions than answers? An overview and suggestions for future research doi:10.1177/0269881119857204 Being first, or most cited, is a fact about history and attention, not about effect.
- The 1/3/1 rhythm
- One dose day followed by two rest days, repeating every fourth day; dose days land on day one, four, seven, and so on. [2] Observational Might Microdosing Psychedelics Be Safe and Beneficial? An Initial Exploration doi:10.1080/02791072.2019.1593561
- Rest days for tolerance
- Spacing doses is meant to avoid the rapid 5-HT2A tolerance that daily dosing would be expected to produce. [1] Peer-reviewed Psychedelics doi:10.1124/pr.115.011478
- Contrast days for comparison
- Alternating dose and non-dose days gives a self-tracker a within-person comparison — and the comparison most exposed to expectation. [3] Clinical trial Self-blinding citizen science to explore psychedelic microdosing doi:10.7554/eLife.62878
- The largest observational dataset
- Fadiman’s diary work with over a thousand people is the most extensive descriptive record behind any schedule — and entirely uncontrolled. [2] Observational Might Microdosing Psychedelics Be Safe and Beneficial? An Initial Exploration doi:10.1080/02791072.2019.1593561
- Documented, not proven
- No controlled trial has tested the schedule, and no study has compared it against another; expectancy and placebo findings limit what the self-reports establish. [5] Observational A systematic study of microdosing psychedelics doi:10.1371/journal.pone.0211023 [6] Systematic review Is microdosing a placebo? A rapid review of low-dose LSD and psilocybin research doi:10.1177/02698811241254831
Frequently asked questions
What exactly is the Fadiman 1/3/1 protocol?
It is a four-day repeating cycle: a dose on day one, no dose on days two and three, and a return to dosing on day four — so dose days fall on day one, day four, day seven, and so on. [2] Observational Might Microdosing Psychedelics Be Safe and Beneficial? An Initial Exploration doi:10.1080/02791072.2019.1593561 The “1/3/1” shorthand captures the idea of one dose day inside a roughly three-day window. The two rest days are the defining feature; they are meant to limit tolerance and to create non-dose days a person can compare against their dose days.
Why is it the most recommended starting point?
Mostly because it is the most documented. James Fadiman gathered self-reports from over a thousand people across dozens of countries, which is the largest descriptive dataset behind any schedule, and most later practitioner writing treats it as the baseline. [2] Observational Might Microdosing Psychedelics Be Safe and Beneficial? An Initial Exploration doi:10.1080/02791072.2019.1593561 That makes it a sensible default for someone who has decided to microdose and wants a structured, well-described routine — but “most documented” is a statement about how much observational data exists, not evidence that it produces better outcomes than other schedules. [7] Peer-reviewed Microdosing psychedelics: More questions than answers? An overview and suggestions for future research doi:10.1177/0269881119857204
How strong is the evidence that the Fadiman protocol works?
The evidence that people following it report benefits is substantial but observational and uncontrolled — it cannot separate the dose from expectation. [5] Observational A systematic study of microdosing psychedelics doi:10.1371/journal.pone.0211023 The evidence that it works better than placebo, or better than other schedules, is essentially absent: there has been no controlled trial of the schedule itself, and the strongest controlled microdosing study found benefits under placebo as well as active dose. [3] Clinical trial Self-blinding citizen science to explore psychedelic microdosing doi:10.7554/eLife.62878 The protocol is well described, not well proven.
How long should one cycle run before evaluating?
Practitioner convention is to run a schedule for several weeks — commonly around four — before judging it, on the reasoning that a handful of dose days is too little signal to read. This is sound advice for orderly self-observation rather than a finding from research, and it carries a quiet risk: a longer commitment also gives expectation more time to shape what you report. [3] Clinical trial Self-blinding citizen science to explore psychedelic microdosing doi:10.7554/eLife.62878 The length-of-cycle question and its trade-offs are covered in tolerance and cycling.
Is the '1/3/1' the same thing as one-day-on, two-days-off?
Yes — they describe the same rhythm. One dose day followed by two rest days, repeating every fourth day, is the core of the schedule whichever shorthand is used. [2] Observational Might Microdosing Psychedelics Be Safe and Beneficial? An Initial Exploration doi:10.1080/02791072.2019.1593561 The numbers refer to the pattern of dose and rest days, not to doses or quantities.