Substance evidence
Microdosing
Where placebo control is enforced, most of the benefit disappears.
What Its Legal Status Actually Means
Read this before anything below it. Legal to sell is not the same fact as reviewed, verified, or approved.
The substances used for microdosing are federally illegal. Psilocybin, psilocyn, and lysergic acid diethylamide are all listed in Schedule I of the Controlled Substances Act at 21 CFR 1308.11(d) — the schedule reserved for drugs with no currently accepted medical use and a high potential for abuse — with no FDA-approved product and no approved indication of any kind. Nothing sold or shared as a "microdose" is an approved medicine; there is no legal, quality-controlled supply, so dose and purity are unverified. A small number of state and municipal programmes (for example Oregon's supervised psilocybin services and Colorado's healing centres) permit supervised adult use of psilocybin under state law, but those frameworks cover supervised sessions, not take-home microdose regimens, and they do not change federal law.
Quoted whole from the 2026-08-18 study harvest. Not summarized, not shortened.
What the Research Shows
4 records from the 2026-08-18 harvest, each checked against PubMed and Europe PMC on that date. How a study was designed, how many people were in it, and who paid for it are printed above what it found, because those three facts decide how much the finding is worth.
Study 1 · 2026
- Systematic review of randomized trials
- 3,681 participants
- Reputable journal
- Funding not established
- Preregistered
- Declared conflicts of interest
strong72/100Well-supported by good-quality research.
Read this first: The meta-analytic estimates rest on very little randomised data — two parallel RCTs (three comparisons, n=117) for efficacy and two RCTs (n=109) for adverse events — so the confidence intervals are wide and the review is better read as demonstrating absence of evidence than proving absence of effect. Several authors are affiliated with psychedelic research centres and one is chief medical officer of a psychedelics company (disclosed), so the null result is not coming from sceptics.
The most recent synthesis — 24 studies and 3,681 participants, searched to February 2026 — found that in randomised trials microdosing produced no clear reduction in depressive symptoms (SMD -0.19, 95% CI -0.56 to 0.19), anxiety (SMD -0.20, -1.11 to 0.71), or stress (SMD 0.02, -0.39 to 0.43), with adverse-event rates similar to control. Observational studies reported mood and personality improvements, which the authors attribute to expectancy and lifestyle factors rather than drug effect.
How this record was checked
PubMed record 42593636 fetched via NCBI efetch 2026-08-18; title, authors, journal, publication (CNS Drugs, online ahead of print 13 Aug 2026), DOI, 24 studies, 3,681 participants, PROSPERO registration CRD420251035294, all three SMDs, and the conflict-of-interest declaration confirmed from the record. Europe PMC core record checked the same day: not open access, no grant or funding statement retrievable and the publisher page is behind authentication, so funding is recorded UNKNOWN.
Study 2 · 2021
- Randomized trial
- 191 participants
- Reputable journal
- No funding reported
- Declared conflicts of interest
strong70/100Well-supported by good-quality research.
Read this first: Participants sourced and weighed their own material, so actual doses were unverified, and the sample was self-selected enthusiasts rather than people with a diagnosed condition. The authors are based at Imperial College's Centre for Psychedelic Research with a co-author from the Beckley Foundation, both proponents of psychedelic research — which cuts against, not toward, a bias explanation for this null result.
191 people already intending to microdose followed online instructions to build their own placebo control into their routine. Every psychological outcome improved from baseline over four weeks in the microdose group — and improved just as much in the placebo group, with no significant between-group differences. The few acute differences that did appear were explained by participants correctly guessing which capsules were active.
Szigeti B, Kartner L, Blemings A, et al. (2021). Self-blinding citizen science to explore psychedelic microdosing. eLife. PMID 33648632.
How this record was checked
PubMed record 33648632 fetched via NCBI efetch 2026-08-18; title, authors, journal, year, DOI, and n=191 completers confirmed from the abstract, along with the competing interests declaration ("no competing interests declared"). Europe PMC full text (PMC7925122) fetched the same day states "No external funding was received for this work", hence funding NONE; no preregistration statement found in the full text, so preregistered is recorded false.
Study 3 · 2022
- Randomized trial
- 34 participants
- Reputable journal
- Independently funded
- Declared conflicts of interest
strong78/100Well-supported by good-quality research.
Read this first: With 34 participants the study is underpowered to detect small true effects, and the authors' own Bayesian analysis in the successfully blinded subgroup was inconclusive rather than clearly negative.
34 people beginning to microdose took 0.5 g of dried Psilocybe cubensis or placebo under double-blind conditions. Subjective effects were stronger on the active dose only among participants who correctly guessed which condition they were in, and EEG theta power dropped; on every other measure — wellbeing, creativity, cognition, perception — there was no benefit, with a few small changes in the direction of cognitive impairment.
How this record was checked
PubMed record 35918311 fetched via NCBI efetch 2026-08-18; title, authors, journal, year, DOI, n=34, and the 0.5 g dose confirmed from the abstract, along with the competing-interests declaration. Europe PMC full text (PMC9346139) fetched the same day: funded by grant PICT-2019-02294 from Argentina's Agencia Nacional de Promoción Científica y Tecnológica with partial funding from the Czech Ministry of Health (NU21-04-00307) and the Czech Science Foundation (20-25349S) — all public agencies, hence INDEPENDENT.
Study 4 · 2019
- Cohort study
- 98 participants
- Indexed journal
- No funding reported
- Declared conflicts of interest
moderate64/100Reasonable evidence with real limitations.
Read this first: Uncontrolled and unblinded: participants knew they were dosing, sourced their own substances, and were self-selected enthusiasts, so nothing here can separate drug effect from expectation. The authors say as much and explicitly call for dose- controlled research.
98 microdosers gave daily ratings over six weeks: psychological functioning rose on dosing days with little carry-over to the following days, and pre-to-post measures showed lower depression and stress and less distractibility — but also higher neuroticism. A companion survey of 263 people found that expectations of benefit were large, wide-ranging, and largely unrelated to what the actual microdosers reported, which is the signature of expectancy rather than pharmacology.
Polito V, Stevenson RJ. (2019). A systematic study of microdosing psychedelics. PLOS ONE. PMID 30726251.
How this record was checked
PubMed record 30726251 fetched via NCBI efetch 2026-08-18; title, authors, journal, year, DOI, and the sample sizes (98 daily-rating participants, 63 completing psychometrics, 263 in the expectancy study) confirmed from the abstract. Europe PMC full text (PMC6364961) fetched the same day states "The authors received no specific funding for this work", hence funding NONE, and declares no competing interests.
The Risks
Nobody checks this purchase the way a prescription is checked. No prescriber reviews it against the rest of what you take, no pharmacist screens the interaction, and no regulator confirms the dose in the capsule before it is sold. That is why this section sits here at full length rather than as a footnote.
What the paragraph below covers:
- Heart and blood pressure
- Psychosis and mania
- Drug interactions
- What is actually in the product
Possession is a federal felony and material is bought from unregulated sources, so the identity, purity, and strength of what people take is unknown — dried mushroom potency varies severalfold and "LSD" tabs are a common vehicle for substituted NBOMe compounds, which are far more toxic. Because microdosing means repeated dosing over weeks or months, its risk profile is not the same as a single supervised session: no trial has run long enough to characterise chronic effects. The most-discussed theoretical concern is cardiac — psilocin and LSD are agonists at the 5-HT2B receptor, the same receptor implicated in the valvular heart disease caused by fenfluramine and pergolide, and sustained low-level 5-HT2B agonism is the exposure pattern that caused that damage; no study has yet tested whether chronic microdosing does the same, so this is an unquantified risk rather than a demonstrated one. Controlled studies have found small shifts toward cognitive impairment rather than enhancement, and self-report studies list physiological discomfort and increased anxiety among reported downsides. People with a personal or family history of psychosis or bipolar disorder are excluded from psychedelic trials for good reason, and serotonergic interactions with antidepressants are not characterised at these doses.
What Is Not Known
The boundaries of the section above, in the harvest’s own words. What it excluded, why, and where it looked and found nothing. An absence of evidence is not evidence of absence, and it is not evidence of benefit either.
This file is the honest counterweight to the clinical psychedelics lane. Macro-dose psilocybin and MDMA trials — supervised, single or double sessions, with psychological support — live in the 2026-08-17 PSYCHEDELICS batch and are a different intervention with a different evidence base. Microdosing means sub-perceptual doses (roughly a tenth of a recreational dose) taken repeatedly, usually unsupervised and self-sourced. The controlled evidence for it points the other way: where placebo control is enforced, the benefits largely disappear.
What Was Left Out, and Why
Quoted from the harvest, where these notes sat above the study list rather than after it. Where a note says “below” it means the studies in the section above.
- Open-label and uncontrolled microdosing surveys (Anderson 2019, Rootman 2021 and similar app-based cohorts) excluded: every one of them is self-selected, and the controlled studies below exist precisely to test what those surveys cannot.
- Lo 2024 systematic review in Prim Care Companion CNS Disord (PMID 38228068) was verified but dropped in favour of the 2026 CNS Drugs meta-analysis, which supersedes it and actually pools effect sizes.
- No microdosing study in a clinical population with a diagnosed psychiatric disorder met inclusion; all controlled work below is in healthy or self-selected volunteers. That absence is itself the finding.
The Retraction Check
PubMed efetch records for all four PMIDs (33648632, 35918311, 30726251, 42593636) inspected 2026-08-18 for "Retraction in" flags; none present.
Questions for a Prescriber or Pharmacist
This page does not tell anyone to take Microdosing or to avoid it. It is not able to: it does not know what else you take, what you have tried, or what you are treating. These are the questions each study above raises, written to be asked out loud.
- The randomised evidence shows microdosing performing no better than placebo for depression, anxiety, or stress — what treatment with an actual demonstrated effect should I be trying first?
- In the largest placebo-controlled microdosing study, people taking empty capsules improved as much as people taking the drug — how do I tell whether what I am feeling is the substance or the expectation?
- This study found the only reliable difference from placebo was in people who knew they had taken the active dose, and no gain in creativity or cognition — what am I actually expecting microdosing to do for me?
- Observational microdosing data show people expect far more benefit than users actually report, and one measure — neuroticism — went up. Is that a trade I would knowingly make?
And the one to ask at the counter, whatever the answers above turn out to be: given everything I am already taking, what would you want to know about Microdosing before I put it in the same body?
Where This Page Comes From
Transcribed from the study-harvest-2026-08-18 record for microdosing, built into this page by scripts/supplement-ingest.mjs on 2026-09-07. Nothing here is fetched at page load, and nothing here was written by a model without a citation behind it.
| Source file | study-harvest/2026-08-18/microdosing.yaml |
|---|---|
| Source repo | REPTechnologies/avalo-backend |
| SHA-256 | 2170832b91cbb71ac8031c350f639b781d2f3252c399eb0f8a11d10274422143 |
| Also searched as | microdose, LSD microdosing, psilocybin microdosing, sub-perceptual dosing |
The Other Substances
- 5-HTP
- Ashwagandha
- Cannabidiol (CBD)
- Cannabis and THC
- Creatine
- Kratom
- L-Theanine
- Magnesium
- Melatonin
- Methylene Blue
- N-Acetylcysteine (NAC)
- Omega-3
- Phenibut
- SAMe
- St John’s Wort
- Valerian
Do any supplements actually work? asks the question across all of them. The full library has the medication records, the funding investigations, and the glossary.