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Gender

One of Metanoia's six disciplines: how sex, gender and hormonal state relate to the response to natural psychedelics, and how little of that has been measured

Last reviewed 5 October 2026

Read this first. This page is education, not instructions to use. Metanoia does not supply any substance. In the United States, most of the substances discussed here are Schedule I under federal law (21 CFR 1308.11), their legal status differs between countries and between US states, and none of this is legal advice. Nothing here is medical advice, and nothing here describes or recommends a dose. "Healthy adults" means people with no diagnosed psychiatric or major medical condition, the population Metanoia studies. A great deal of psychedelic research was done in clinical populations, and much of the evidence on sex and gender comes from small groups, from secondary analyses of studies built to answer other questions, or from animals. Where a study below used a clinical group or an animal model, the text says so, because it changes what the result can mean for everyone else.

What it is

This page uses two words that are often treated as one. Sex is a biological variable, usually the sex assigned at birth in a research record, and it travels with chromosomes, hormones, body size and the way the body handles a drug. Gender is a social variable, usually a person's self-described identity, and it travels with roles, expectations, stress and the way an experience is understood. For many people the two line up, for others they do not, and a study that collects one has not collected the other. Hormonal state is a third idea, a biological condition that differs between people of the same sex and changes within one person, such as the phase of the menstrual cycle, pregnancy, hormonal contraception and menopause.

Almost all of the evidence below is about sex, and in most of it sex means a two-category label, male or female, taken from a study form. Almost nothing is known about gender as a social variable in psychedelic research. When a source reports gender identity, the text says so.

Metanoia is a California 501(c)(3) public charity advancing the science of natural psychedelics for personal growth and human flourishing in healthy adults. This discipline asks a plain question on behalf of that population. When researchers describe how people respond to these substances, do they know whether the answer holds for women, for men, for people in different hormonal states, and for people whose gender identity differs from the sex recorded at birth? And does the record they keep make it possible to find out?

What is known

The short version. Women make up close to half of the participants in the recent psychiatric trials that have been counted, but no count for healthy-volunteer studies was found. In healthy adults, the picture for psilocybin and LSD is mixed. Most pooled analyses find no consistent sex difference in the acute experience, a few find small signals, and one 2026 preprint reports higher subjective ratings in women. The MDMA studies, which involve a synthetic substance and are included only for comparison, point toward stronger effects and more adverse effects in women. Evidence on gender identity comes almost entirely from surveys and interviews, and Oregon's registry questionnaire records sex at birth, pregnancy and contraception but not cycle phase.

Who is in the studies

A 2025 analysis of trials registered on ClinicalTrials.gov up to 12 January 2025 found nine eligible phase 2 to 4 trials of classic psychedelics, eight with psilocybin and one with LSD. In the eight psilocybin trials (501 participants), 47.7 percent were women [1]. That is close to parity, and it is a count of psychiatric trials. The authors excluded trials that enrolled only healthy participants, so the figure cannot say who takes part in the healthy-volunteer studies this discipline cares about, and no equivalent count was found for that literature.

A 2025 systematic review of 21 controlled trials of psychedelic-assisted therapy (12 with psilocybin and 9 with MDMA, 1,034 participants, all in clinical populations) found 55.4 percent women overall in a single field for gender or sex: 50.8 percent in the psilocybin trials (718 participants) and 65.8 percent in the MDMA trials (316 participants). No trial reported non-binary or transgender participants, no trial made clear whether that field meant sex at birth or gender identity, and only four of the 21 analysed outcomes by sex or gender [27].

Oregon's state-regulated psilocybin services keep a registry of clients, and a 2026 analysis covered 346 participants. Asked about gender, 52.5 percent said woman, 45.8 percent man, and six people (nonbinary, transgender or other) made up the rest. These are service clients, not a healthy-adult sample, since their psychiatric diagnostic status is unknown and their reasons for seeking services varied. The baseline table lists gender in five categories and the results text calls the women "female", but the supplement shows separate items for gender and for sex assigned at birth (female, male, intersex) and items on pregnancy, breastfeeding, trying to conceive and contraception. It reports 53.3 percent female sex in the cohort against 57.9 percent among all 6,887 Oregon clients from January 2025 to March 2026. It lists no item for cycle day, cycle phase or hormone levels, and neither the paper nor its supplement analyses any outcome by sex or by gender [2].

The state's public dashboard for 2025 covers 5,935 clients. Among those who gave a gender, about 57 percent were women, about 39 percent men and between 3 and 4 percent non-binary. The analysis reports 57.4, 39.6 and 3.0 percent, but its own table counts (2,001 women, 1,382 men and 145 non-binary, 3,528 answers in all) give 56.7, 39.2 and 4.1 percent. The table covers about 59 percent of the clients, and the share of women ranged from 54.5 to 59.0 percent across quarters [3].

Women are present in the samples counted, but the sharper problem is the distance between enrolling people and analysing results by sex. A 2011 review found that female animals were neglected in biomedical research for decades and that studies including both sexes frequently failed to analyse by sex [4], and much of the mechanistic understanding of psychedelics comes from preclinical work in male animals only [15].

Does sex predict the acute experience in healthy adults?

Most human evidence comes from pooled analyses of controlled studies in healthy volunteers, many from one Basel group, so the findings below are not fully independent confirmations of each other.

LSD. In a Basel study of oral LSD, 8 men and 8 women gave blood samples over 24 hours. The concentration profiles looked alike, with a peak plasma concentration of 4.4 ng/mL in men and 4.2 ng/mL in women (geometric means). The terminal half-life was numerically longer in men (10.2 hours against 7.6 hours in women), with wide spread and no significance reported. The authors state that the study had 52 percent power, roughly an even chance of detecting a real difference of the size it was built to find, and could not exclude a sex difference [6]. A later pooled analysis of two crossover studies in 40 healthy volunteers found no association between sex and the effects of LSD, but it includes the same 16 volunteers and is not an independent check [26].

A larger pooled analysis of nine crossover studies (213 healthy participants, 108 of them women, 297 LSD sessions) found dose to be the strongest predictor of nearly everything, and the authors conclude that sex and body weight had no significant influence on the experience [10]. In the main models, female sex went with smaller increases in "good drug effect," unity, insightfulness and positive mood and with smaller changes in body temperature, and a sensitivity analysis, did not find the difference in how positive the experience felt statistically significant [10]. The analysis corrected 551 tests for multiple comparisons, and the main text does not say whether the sex differences survive that correction.

Psilocybin. A post hoc analysis pooled 288 participants from ten studies at one center, a mixed group in which healthy volunteers made up 70 to 81 percent of the three groups and 53 to 56 percent were women. No significant association appeared between sex and mystical, challenging or overall intensity ratings. For challenging effects the p values were 0.045 in one group and 0.021 in the group given a near-fixed amount, which the authors call a trend because the corrected threshold was 0.004, saying cautiously that women may score marginally higher on self-reported challenging effects [11].

A 2025 placebo-controlled crossover study enrolled 40 healthy adults. The sex analysis covered the 39 in its EEG arm, 19 of them women, with sex entered as a factor in repeated-measures tests, and found no significant effect of sex on the acute or the lasting measures. The amount was set by body weight, the fMRI arm had 26 participants, the authors describe most findings as exploratory and not powered, and women's sessions were scheduled outside menstruation, so cycle phase was set by design and never measured [12]. A systematic review of 14 studies of what predicts a person's reaction concluded that sex was not a robust predictor, but it was not built to test sex, and its one study linking female sex to a "bad trip", a text analysis of 346 online trip reports, found a small effect that the authors say may reflect greater willingness among women to report negative experiences. The conclusion rests on a handful of small, mostly open and retrospective studies [13].

A 2026 preprint. A bioRxiv preprint from 2026, not peer reviewed and rated level 3, points the other way. It pooled two double-blind, placebo-controlled studies in healthy, experienced volunteers aged 18 to 40 who received psilocybin, LSD or 2C-B, a synthetic compound. The current version, from 19 August 2026, analyses 94 drug sessions from 72 participants, 40 of them women. After adjusting for age, women rated five subjective measures higher than men, most clearly the feeling of being under the drug's influence, reduced vigilance, and impaired control and cognition, with Cohen's d from 0.50 to 0.73 and no correction for multiple comparisons. The first version, from 13 July 2026, found three of the five significant. Blood exposure and empathy ratings did not differ between the sexes. The authors describe a secondary analysis that the studies were not designed for, with large unexplained variability among women and no measure of cycle phase. The figures are provisional [28].

MDMA. MDMA is a synthetic substance, not a natural psychedelic, included here only as a comparison because it is where sex differences have been reported most often. A pooled analysis of six placebo-controlled studies (118 volunteers, 55 women) found that MDMA raised emotional empathy and that sex did not change the size of that effect. At the higher of the two fixed amounts, women also had higher blood concentrations of MDMA, so equal fixed amounts did not give equal exposure, and the authors note that a larger effect in men could have been hidden [7].

Older Basel analyses report sex differences. In 74 healthy volunteers (54 men, 20 women) given MDMA in amounts adjusted to body weight, psychoactive and adverse effects were more frequent and intense in women, while men showed larger rises in blood pressure [8]. In a safety analysis of nine studies with 166 healthy volunteers, half of them women, "bad drug effect" ratings were higher in women after adjusting for body weight and blood concentration, acute complaints scored 8.8 in women against 6.4 in men, and men showed the larger rise in systolic blood pressure once the results were adjusted for weight. Duration of effects and general vital signs before adjustment did not differ [9].

How to read all of this. Not one of these analyses was designed to detect a sex difference. Most are secondary analyses, several have about twenty women or fewer, and the one that reports its statistical power gives 52 percent. For psilocybin, a pool of 261 healthy volunteers from 23 controlled studies in Zurich, 100 of them women, found that gender, a two-category field that is in effect sex, was not associated with any response measure, but the authors chose their predictors by a selection procedure, so this is not a direct test [25]. For psilocybin and LSD the right reading is mixed: several pooled analyses found no consistent sex difference, one found a small signal that fails some checks, and one preprint reports higher ratings in women. The evidence does not show that sex matters, and it does not show that it does not.

Hormonal state and the menstrual cycle

If sex matters, hormones are the likeliest route. A 2026 narrative review explains why the idea is plausible. Estradiol and progesterone, the main ovarian hormones, can influence how fast a drug moves through the gut and how it spreads through body tissue, and how the liver breaks it down, including two liver enzymes involved in the breakdown of LSD and of psilocin, the active form of psilocybin. It is careful about what is missing. It states that direct human data on psychedelic pharmacokinetics across hormonal states are absent, that the human receptor data come from blood platelets and brain imaging, and that suggested peaks of sensitivity in some cycle phases rest on limited direct evidence, and its own summary table marks most hormone effects as speculative or understudied [14]. A second 2026 review, which treats sex as a biological variable and does not address gender identity, says that direct, adequately powered analyses by sex remain limited and that including both sexes is necessary but not sufficient [29].

Some human receptor work does exist, though not with psychedelics given to people. In 28 healthy women not using oral contraceptives, binding of a radiolabelled LSD to the 5-HT2A receptor on blood platelets was higher in the early follicular phase (early in the cycle, before ovulation) and the early luteal phase (just after ovulation) than in the mid-luteal phase [16]. A smaller study of six women, with cycle phase based on self-report, found binding rising between the first and the second week. The two studies point in different directions, and the 2026 review calls the patterns divergent and their relevance to the brain uncertain [14]. Platelets stand in for the brain and no one was given a psychedelic, so the studies show at most that binding in a peripheral tissue may vary with the cycle, and they do not agree on how.

A 2025 opinion paper argues that ovarian hormone fluctuation is insufficiently examined and recommends tracking menstrual phase and measuring hormones in trials [15]. It carries no new data and notes that the effect of hormonal contraception on the response to a psychedelic has not been studied directly in people. Its practical advice about timing is not repeated here, because it is advice and not evidence. Its statement that female rodents consistently show a stronger head-twitch response is broader than the mouse dose-response study described below supports [15] [19].

One survey comes closest to data on behaviour. Of 703 respondents, 634 had a menstrual cycle in the past year and 167 had a provider-diagnosed premenstrual dysphoric disorder. Psychedelics were used to manage premenstrual mood symptoms by 5.9 percent of the participants and 16.2 percent of those with the disorder. The abstract does not state the denominator of the 5.9 percent or say that the category was limited to natural psychedelics, and use was reported more often in the luteal phase than in the follicular phase [17].

The first dedicated measurement is a protocol, not a result. A protocol published in August 2026 plans an open-label study in healthy menstruating people, with 21 participants in a cycle sub-study and 12 in a tolerance sub-study, measuring subjective effects, EEG brain activity and blood levels [18]. The study is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12625000991415, 8 September 2025, University of Auckland) as an open-label, single-group, phase 1 trial with a target of 21 healthy women, not yet recruiting and not updated since registration. The entry plans sessions in three cycle phases, excludes people on hormonal contraception and does not include the 12-person tolerance sub-study, and the protocol title says persons while the registry limits enrolment to females [24]. No results are available. The study does not appear on ClinicalTrials.gov. Searches on 2 and 4 October 2026 for the menstrual cycle with psilocybin, LSD, MDMA or psychedelic found no registered trial, and only one related record, a psilocybin trial in premenstrual dysphoric disorder (NCT07818720, not yet recruiting, 32 planned participants), which is a clinical question [23].

Animal studies

Animal work can vary hormones and sex in ways that human studies cannot. In a dose-response study in male and female C57BL/6J mice (12 of each sex for each of DOI, a laboratory compound acting on the same receptor, LSD and psilocybin), receptor affinities were similar in the two sexes. The head twitch, a behavioural proxy for psychedelic-like effects, had similar potency for DOI and psilocybin and differing dose-response curves for LSD. The maximum response was higher in females, significantly for DOI and LSD and not for psilocybin, and the sex differences appeared only at amounts at least ten times the ED50, the amount that produces half of the maximum response. The authors conclude that commonly used amounts produce comparable effects in the two sexes, and they name as a limitation that they did not monitor the estrous cycle of the mice [19].

A 2026 review of rodent research reports that behavioural outcomes frequently show stronger or qualitatively distinct effects in females, with the estrous phase the most consistent predictor of whether a sex difference appeared and sex alone a weaker one. The authors chose 21 core papers from roughly ten thousand ranked search results because those papers clearly show sex-dependent effects, so the selection leans toward positive findings, and their statement about the estrous phase rests on three or four studies, only one of which examined the cycle directly with LSD. They also write that it is inaccurate to generalise that females are either more or less vulnerable, and that a rodent model cannot capture subjective experience, set, setting or integration [20].

Policy

In the United States the National Institutes of Health issued a notice on 9 June 2015 expecting sex as a biological variable to be factored into research designs, analyses and reporting in vertebrate animal and human studies, with strong justification needed for applications that study only one sex. The notice applies to applications for the 25 January 2016 due date and after, subject to approval by the Office of Management and Budget [5]. It covers NIH-funded work only and is a reporting policy, not a finding about drugs.

Gender identity

No controlled study of a classic psychedelic in healthy adults was found that was designed to compare people by gender identity, and none reported outcomes for transgender or non-binary participants in numbers large enough to analyse.

What exists is survey and interview work. A survey of 346 people in the LGBTQIA+ community who had used psychedelics in non-clinical settings found that 57.8 percent were assigned female at birth and that participants identified as women (28.9 percent), genderqueer (19.5 percent), nonbinary (17.6 percent) and men (15.9 percent), with sex at birth and gender recorded as separate fields. A total of 65.3 percent reported changes in their attitudes about gender identity after the experience, and the intensity of the acute experience was linked to later self-acceptance and sexual identity exploration. The design was retrospective and cross-sectional, positive experiences were probably over-represented, the main mystical experience questionnaire has not been validated in gender-diverse groups, and these self-reports cannot establish cause [21]. The 346 respondents are what remained of 9,351 raw records after quality filters, and the group is not a healthy sample: reported diagnoses included anxiety (45.7 percent), depression (48.3 percent) and gender dysphoria (14.5 percent).

A qualitative study of 20 interviews with transgender and gender-expansive adults found three themes: set and setting shaped the quality of the experience, many described increased self-acceptance of their gender identity, and some described challenging experiences including gender dysphoria alongside gender euphoria. The interviewees were chosen from the respondents of the survey above, so the two studies are not independent. All of them reported some benefit, and the authors state that they do not recommend that transgender or gender-expansive people begin using psychedelics [22].

Boundaries in accompanied settings

A related question sits beside sex and gender. When a person takes a psychedelic with a sitter, guide or therapist, a boundary violation by that person is one of the risks that matter, and it is fair to ask whether such events fall differently on people of different genders. No peer-reviewed primary source was found that measures sexual misconduct in accompanied psychedelic settings and reports it separately by gender.

A survey fielded in 2022 and published in 2025, recruited at a United States festival and on social networks, reached 1,221 people with naturalistic psychedelic experience (48.2 percent women, 46.5 percent men, 2.1 percent non-binary and 0.5 percent transgender). In it, 7.9 percent said that they, or someone they knew, had been the victim of inappropriate sexual contact by a sitter, guide or therapist. The question mixes personal experience with second-hand knowledge, the sample is a convenience sample, and the result is not split by the gender of the respondent or of the victim, so the 7.9 percent is not a rate per person [30]. A community survey of 745 people in ayahuasca settings, fielded in 2020 and published in 2023 by Chacruna, is not peer reviewed and is rated level 3. It found that 52.1 percent had direct or indirect experience of sexual abuse, a category that includes hearsay. It also reports a high dropout and no breakdown by gender [31]. In Oregon's registry, the week-one questions on unwanted touch and sexual contact from the facilitator produced no reported instance, and the paper does not give how many people the questions applied to, which does not show that none occurred elsewhere [2]. The international reporting standard for the setting of psychedelic trials asks trials to report verbal or physical interpersonal interventions and how consent for them was obtained, and to report the participant's sense of psychological and cultural safety.

History in brief

A 1993 federal law, the NIH Revitalization Act, required the inclusion of women in federally funded phase III clinical trials [4]. In 2015 the NIH said that women were by then roughly half of participants in NIH-supported clinical research [5]. Animal research lagged far behind, with male-only studies outnumbering female-only studies five and a half to one in neuroscience in the 2009 literature that was surveyed [4]. No published count of women in the mid-twentieth-century psychedelic trials or in the early years of the modern revival was found, so this page makes no claim about them.

What is not known

This part lists what the evidence cannot yet answer and says what the discipline is set up to ask.

Open questions

Does the phase of the menstrual cycle change the acute experience or its lasting effects in healthy adults? Nobody has published a controlled test, and the one protocol found has no results [18] [24]. Does hormonal state change how psilocybin or LSD is absorbed and broken down in people? The authors of the main review say direct human data are absent [14]. Is the weak sex signal in LSD and psilocybin studies real, and does the stronger signal in MDMA studies come from exposure, from body weight or from something else? A study built and powered to test sex would settle more than another pooled secondary analysis.

What is the real count of women in healthy-volunteer psychedelic studies, and what was it in earlier decades? No published figure was found for either. How does gender identity, as a social variable, relate to the experience and to outcomes after it? No controlled data exist. Does the risk of boundary violations in accompanied settings differ by gender? No source found reports it by gender [30] [31]. Do sex, gender or hormonal state matter for any of the twelve dimensions Metanoia follows, from emotional resilience to leadership? No study was found that looked at sex differences across the twelve dimensions as a framework.

Limits of the evidence

Samples are small, and the number of women in each analysis is often twenty or fewer. The human findings come mostly from secondary analyses of studies built for other purposes. Hormonal state is almost never measured. The main international reporting standard for the setting of psychedelic trials was checked item by item. None of its 30 items asks for the sex, gender or hormonal state of participants, which follows from its scope and is not a flaw, and an item on the demographics of facilitators fell short of the agreement threshold [32]. No reporting standard in this area that makes those fields mandatory was found.

What Metanoia asks

The discipline treats sex, gender and hormonal state as things a research record needs to hold, so that the questions above can be asked of any dataset, including a cohort Metanoia may one day study. The questions that follow are about the record itself.

  • Can sex and gender be recorded as separate fields, sex as assigned at birth and gender as self-described identity, so that the record shows when the two differ?
  • Where hormonal state is relevant, can it be recorded, and with which measure?
  • When a sample is large enough to say anything, do results differ by sex or by gender? When it is too small, how can a report say so plainly?
  • Can adverse experiences involving boundaries be recorded so that they can be analysed by the gender of the participant and of the facilitator?
  • For each of the twelve dimensions, from Emotional Resilience to Leadership, does the result change with sex, gender or hormonal state, or does it stay the same?

A difference and the absence of a difference are both worth reporting. Metanoia does not claim that the answers are known.

Sources

Reliability levels follow Metanoia's scale: level 1 is a primary source or any peer-reviewed publication, reviews included. Level 2 is a reliable secondary source that is not peer reviewed. Level 3 is grey literature, community material or a preprint. Level 4 is a traditional or ethnographic source. Every entry below is level 1, because each is a peer-reviewed publication, an official policy notice or an official registry, with two exceptions marked level 3: a preprint (28) and a community survey report (31). The design is noted separately, because a narrative review or an opinion paper carries less weight than a trial even in a peer-reviewed journal. "Read in full" means the whole main text, and supplements only where an entry says so. "Abstract only" means the abstract was the basis, and the entry says that the full text was not accessible. Identifiers for sources 1 to 23 were checked on 2 October 2026 and those for sources 24 to 32 on 4 October 2026.

  1. Swieczkowski D et al. J Psychopharmacol 2025, 39(9):1014-1022. DOI 10.1177/02698811251353250 PMID 40643096. Grade 1. Cross-sectional analysis of registered trials. Abstract only. Full text not accessible (publisher access limited). Detail moved from the text: the largest imbalance in the paper was race, with 87.2 percent of participants White, 5.0 percent Asian and 3.0 percent Black. Ethnicity was reported in only four of the eight psilocybin trials (134 participants), and 13.4 percent of them identified as Hispanic or Latino. In the four trials run only in the United States, the ratio of participation to population share was 0.317 for Black participants and 0.799 for Asian participants.
  2. Korthuis PT et al. JAMA Netw Open 2026, 9(8):e2630608. DOI 10.1001/jamanetworkopen.2026.30608 PMID 42616497. Grade 1. Prospective observational cohort, n = 346, Oregon. Read in full, including Supplement 1. Detail moved from the text: the mean age was 49.5 years and 86.7 percent were White. Six of 345 people who answered the gender question identified as nonbinary, transgender or other. The week-one questionnaire also asks whether the facilitator made physical contact the participant had not agreed to and whether the facilitator initiated sexual contact, and the paper states that no instances were reported without giving the number of people the questions applied to (see the section on boundaries).
  3. Yu F et al. Front Psychiatry 2026, 17:1777387. DOI 10.3389/fpsyt.2026.1777387 PMID 42233004. Grade 1. Descriptive analysis of public aggregate dashboard data, 2025. Read in full. Detail moved from the text: a 27.2 percent LGBTQ+ figure comes from the sexual orientation question and is not a measure of gender identity. The dashboard holds aggregate counts of service clients, who seek services for wellness and for mental health reasons alike.
  4. Beery AK, Zucker I. Neurosci Biobehav Rev 2011, 35(3):565-572. DOI 10.1016/j.neubiorev.2010.07.002 PMID 20620164. Grade 1. Review of sex bias in 10 fields of mammalian research (2009 literature). Read in full (author version).
  5. National Institutes of Health. Notice NOT-OD-15-102, Consideration of Sex as a Biological Variable in NIH-funded Research, released 9 June 2015. https://grants.nih.gov/grants/guide/notice-files/NOT-OD-15-102.html. Grade 1. Official policy notice. Read in full on 4 October 2026.
  6. Dolder PC et al. Int J Neuropsychopharmacol 2016, 19(1):pyv072 (published online 24 June 2015). DOI 10.1093/ijnp/pyv072 PMID 26108222. Grade 1. Placebo-controlled crossover pharmacokinetic study, 8 men and 8 women. Read in full. Detail moved from the text: the authors flagged one difference, in urinary recovery of the main metabolite during a single collection window, and it vanished over the full 24 hours.
  7. Kuypers KPC et al. J Psychopharmacol 2017, 31(5):589-598. DOI 10.1177/0269881117699617 PMID 28372480. Grade 1. Pooled analysis of six placebo-controlled studies, n = 118. Read in full. Detail moved from the text: the pool had 55 women and 63 men. Women reported more concern for the people in the test pictures and higher everyday empathic concern, with or without the drug.
  8. Liechti ME, Gamma A, Vollenweider FX. Psychopharmacology 2001, 154(2):161-168. DOI 10.1007/s002130000648 PMID 11314678. Grade 1. Pooled analysis of three controlled studies, n = 74. Abstract only. Full text not accessible.
  9. Vizeli P, Liechti ME. J Psychopharmacol 2017, 31(5):576-588. DOI 10.1177/0269881117691569 PMID 28443695. Grade 1. Pooled safety analysis of nine studies, n = 166. Read in full (author version, tables not verified).
  10. Vizeli P et al. Transl Psychiatry 2024, 14(1):357. DOI 10.1038/s41398-024-03074-9 PMID 39231959. Grade 1. Pooled analysis of nine crossover studies, n = 213. Read in full (main text, supplement not accessible). Detail moved from the text: the analysis tested sex alongside dose, age, body weight, personality, mood and genetics.
  11. Garcia-Romeu A et al. J Psychopharmacol 2021, 35(4):353-361. DOI 10.1177/0269881121991822 PMID 33611977. Grade 1. Post hoc pooled analysis of ten studies, n = 288, mixed healthy and clinical samples. Read in full (main text, supplement not accessible). Detail moved from the text: besides healthy volunteers the groups included people trying to quit smoking, people with life-threatening cancer diagnoses and distress, and meditators.
  12. Kluckova T et al. Pharmacol Rep 2025, 77(4):1024-1039. DOI 10.1007/s43440-025-00742-5 PMID 40522607. Grade 1. Placebo-controlled crossover study in healthy adults, n = 40, largely exploratory. Read in full (main text, supplement not accessible).
  13. Aday JS et al. ACS Pharmacol Transl Sci 2021, 4(2):424-435. DOI 10.1021/acsptsci.1c00014 PMID 33860172. Grade 1. Systematic review of 14 studies. Read in full.
  14. Kuypers KPC et al. Mol Psychiatry 2026. DOI 10.1038/s41380-026-03801-2 PMID 42552418. Grade 1. Narrative review, framed around women's mental health and treatment. Read in full (main text, reference list not read). Detail moved from the text: the review also discusses how the density of the serotonin 2A receptor, the main target of classic psychedelics, might change across the cycle.
  15. Cohen ZZ, Blest-Hopley G. ACS Pharmacol Transl Sci 2025, 8(7):1837-1846. DOI 10.1021/acsptsci.5c00255 PMID 40672681. Grade 1. Opinion and perspective paper. Read in full.
  16. Wihlback AC et al. Psychoneuroendocrinology 2004, 29(6):757-766. DOI 10.1016/S0306-4530(03)00120-3 PMID 15110925. Grade 1. Platelet receptor binding across the cycle in 28 healthy women. Abstract only. Full text not accessible.
  17. Nazareth M et al. J Womens Health 2026, 35(10):994-1003. DOI 10.1177/15409996261459360 PMID 42318639. Grade 1. Online survey, n = 703, self-reported use. Abstract only. Full text not accessible.
  18. Kothiwala FM et al. Pharmacology 2026 (published 10 August 2026). DOI as listed by PubMed: 10.1159/pha/aejag002 (it resolves to a Crossref page marked pending publication, checked 4 October 2026). PMID 42574302. Grade 1. Trial protocol, no results. Abstract only. Full text not accessible.
  19. McGriff SA et al. Psychopharmacology 2025, 242(10):2249-2260. DOI 10.1007/s00213-025-06795-x PMID 40381003. Grade 1. Preclinical dose-response study in male and female mice. Read in full (supplement not accessible). Detail moved from the text: effects on movement and body temperature were similar in both sexes.
  20. Marecki R et al. Front Psychiatry 2026, 17:1824073. DOI 10.3389/fpsyt.2026.1824073 PMID 42528876. Grade 1. Review of rodent studies. Read in full. Detail moved from the text: in one example, an LSD-induced disruption of sensory gating (the brain's filtering of incoming sensation) appeared in males and in post-ovulatory but not pre-ovulatory females.
  21. Lancelotta R et al. J Psychoactive Drugs 2025. DOI 10.1080/02791072.2025.2520224 PMID 40534195. Grade 1. Retrospective online survey, n = 346, self-selected sample. Read in full.
  22. Gaughan SJ et al. Int J Transgend Health 2025. DOI 10.1080/26895269.2025.2478112 PMID 41859327. Grade 1. Qualitative interviews, n = 20. Read in full.
  23. ClinicalTrials.gov, searches via the registry's API on 2 October 2026 (condition "menstrual cycle" with intervention psilocybin OR LSD OR MDMA OR psychedelic) and on 4 October 2026 (psilocybin AND (menstrual cycle OR menstruation)). https://clinicaltrials.gov. Grade 1. Official registry queries, zero results on 2 October and four records on 4 October, one related (NCT07818720, premenstrual dysphoric disorder).
  24. Australian New Zealand Clinical Trials Registry. ACTRN12625000991415, "An open-label trial to test menstrual cycle effects and tolerance to low dose psilocybin in healthy menstruating persons (PsiMen)". University of Auckland. Registered 8 September 2025, last updated 8 September 2025. https://www.anzctr.org.au (search by registry number). Grade 1. Official registry entry. Read in full on 4 October 2026.
  25. Studerus E, Gamma A, Kometer M, Vollenweider FX. PLoS One 2012, 7(2):e30800. DOI 10.1371/journal.pone.0030800 PMID 22363492. Grade 1. Pooled analysis of 23 controlled studies in healthy volunteers, n = 261. Read in full (supplements not accessible).
  26. Dolder PC, Schmid Y, Steuer AE, Kraemer T, Rentsch KM, Hammann F, Liechti ME. Clin Pharmacokinet 2017, 56(10):1219-1230. DOI 10.1007/s40262-017-0513-9 PMID 28197931. Grade 1. Pooled analysis of two crossover studies, n = 40, overlapping with source 6. Read in full (supplement not accessible).
  27. Haft SL, Downey AE, Raymond-Flesch M, Fernandes-Osterhold G, Bradley ER, O'Donovan A, Woolley J. Psychiatry Res 2025, 345:116359. DOI 10.1016/j.psychres.2025.116359 PMID 39823947. Grade 1. Systematic review of 21 controlled trials, n = 1,034. Read in full.
  28. Mason NL, Haijen-Bongers ECHM, Kuypers KPC, Frick A, Toennes SW, Mallaroni P, Ramaekers JG. bioRxiv 2026, version 2 of 19 August 2026 (version 1 of 13 July 2026). DOI 10.64898/2026.07.08.737179 Grade 3. Preprint, not peer reviewed, secondary pooled analysis of two studies, 72 participants and 94 drug observations. Read in full, both versions, from the publisher's XML on 5 October 2026. Note: version 1 reports 31 men and 41 women and three significant measures. Version 2 reports 32 men and 40 women, 43 and 51 observations, and five significant measures, and its summary of updates says the analysis was updated and the results have not changed.
  29. Nasini S, Barzon B, Casile A, Richardson B, Gobbi G, Comai S. Trends Pharmacol Sci 2026, 47(9):1008-1020. DOI 10.1016/j.tips.2026.07.006 PMID 42575820. Grade 1. Narrative review. Read in full (main text, reference list not read).
  30. Kruger DJ, Aday JS, Fields CW, Kolbman N, Glynos N, Barron J, Herberholz M, Boehnke KF. Psychedelic Med 2025, 3(1):41-47. DOI 10.1089/psymed.2024.0011 PMID 40342400. Grade 1. Online convenience survey, n = 1,221. Read in full.
  31. Peluso D. Chacruna survey results on the awareness of sexual abuse in ayahuasca settings. Chacruna Chronicles, 31 January 2023. https://chacruna.net/chacruna-survey-results-on-the-awareness-of-sexual-abuse-in-ayahuasca-settings/. Grade 3. Community survey report, not peer reviewed, n = 745. Read in full.
  32. Pronovost-Morgan C, Greenway KT, Roseman L, ReSPCT Experts. Nat Med 2025, 31(7):2186-2195. DOI 10.1038/s41591-025-03685-9 PMID 40461819. Grade 1. International Delphi consensus on reporting the setting of psychedelic trials. Read in full (main text including Table 3, supplements not read).

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