Psychedelics are among the more promising areas of psychiatric research in a generation. A few compounds show early trial benefit: psilocybin for depression, MDMA-assisted therapy for post-traumatic stress, and psilocybin for the distress of a life-threatening illness. One close relative, esketamine, is already approved for treatment-resistant depression.
The evidence also has a clear limit: these drugs produce effects so noticeable that trials rarely stay blinded, so the measured benefit is likely inflated, and in 2024 the FDA declined to approve MDMA therapy for PTSD and asked for more data. This page is education about what the research shows, where the law stands, and what the risks are. It is not a guide to using these substances, and it carries no dosing or sourcing.
Findings & Outcomes
What It Is
Psychedelics in mental health refers to a small group of very different drugs, studied under close supervision and alongside therapy, for conditions that current treatments often fail. They are not one thing. The classic psychedelics act through the serotonin system, MDMA lowers fear by releasing serotonin, and ketamine acts on a separate system and is the one member of this wider group with regulatory approval.
In the research they share a common structure: a screened patient, a prepared session with trained support, and integration afterward. This page is education, and it carries no dosing and no sourcing.
The Main Compounds
1Classic psychedelics: psilocybin, LSD, DMT
These act mainly by switching on the serotonin 5-HT2A receptor, which changes how the cortex signals and is thought to loosen rigid, self-focused patterns of thought. Blocking that one receptor blocks the experience, which is how researchers know it is central. The best trial evidence here is for depression, including treatment-resistant depression, and for the distress of a life-threatening illness.
2MDMA: the trauma compound
MDMA works chiefly by releasing serotonin along with dopamine and noradrenaline, a different mechanism from the 5-HT2A receptor activation of the classic psychedelics. The effect is reduced fear and a greater sense of trust and connection, used to help people stay with traumatic memories during therapy. Its studied use is in post-traumatic stress disorder.
3Ketamine and esketamine: the dissociatives
Ketamine and its enantiomer esketamine are dissociatives, not classic psychedelics. They act on the NMDA glutamate receptor and produce dissociation. Esketamine nasal spray is approved for treatment-resistant depression and is given in a certified clinic, which makes this the one compound in the wider group with a settled regulatory position.
The Individual Medicines
This page is the overview. Each compound has its own deeper page with its trials, its mechanism, its legal position, and its specific risks:
- Psilocybin: the classic psychedelic with the strongest trial evidence, studied for depression and for the distress of a life-threatening illness.
- MDMA: the trauma compound, studied for post-traumatic stress, and the subject of the 2024 FDA decision.
- Ayahuasca: the Amazonian brew studied mainly for depression, whose MAO-inhibitor action carries a serious serotonin-syndrome risk.
- Ibogaine: studied for interrupting opioid and other substance use, and carrying a documented risk of fatal heart-rhythm disturbance.
- Ketamine and esketamine: the dissociatives, and the one member of this wider group with a settled regulatory position, since esketamine is approved for treatment-resistant depression.
What It Does
The evidence is graded claim by claim in the research section below. It is strongest, and most consistent, for psilocybin in depression. The largest controlled trial gave a single 25 mg dose with therapy and improved treatment-resistant depression by 6.6 points more than a low comparison dose at three weeks, though that gain had faded by twelve weeks. A separate trial in major depression found a large short-term benefit against a waiting list, a comparison that inflates the size. And in people facing a life-threatening cancer, a single psilocybin session with support eased depression and anxiety, with most still improved around six months later.
MDMA-assisted therapy sits at a similar stage for post-traumatic stress, with moderate-to-large benefit over placebo therapy across two phase 3 trials. Esketamine nasal spray, a refined form of ketamine, is the one option here with a settled regulatory position: it is approved for treatment-resistant depression and given in a certified clinic. It is a dissociative drug, so it sits somewhat apart from the classic psychedelics.
Two findings point the other way and weigh across the whole field. Tested head-to-head against a standard antidepressant, psilocybin did not clearly beat it on the main measure. And in the largest placebo-controlled test of microdosing, the people who microdosed improved, but so did the placebo group, and the two did not differ; the gains tracked with people guessing which they had taken.
That mixed picture is the accurate one. For decades the received view held that psychedelics were dangerous drugs of no medical value, a stance set in law in the early 1970s, and the trial evidence no longer supports it. As attention grew, a second belief took hold, that these compounds are close to a cure. The 2024 FDA decision on MDMA is the clearest check on it: despite two positive phase 3 trials, regulators declined to approve MDMA-assisted therapy for PTSD and asked for another trial. The old dismissal and the newer overstatement both go beyond what the data support.
The Research & Studies
Everything here is based on the research we have collected and checked, sorted into groups and ordered with the strongest evidence first. Click any claim to open the studies behind it.
Mood & stress
Esketamine nasal spray, the one approved option here, beat placebo by about 4 points at four weeks
Esketamine nasal spray, taken with an antidepressant, improved depression by about 4 points more than a placebo spray at four weeks on the MADRS depression scale, which runs from 0 to 60, a modest edge. It is the one compound in this area with regulatory approval, and it is a dissociative drug rather than a classic psychedelic.
In the TRANSFORM-2 phase 3 trial, 227 adults with treatment-resistant depression started a new oral antidepressant and were randomized to esketamine nasal spray or placebo spray. MADRS improved by a difference of least-square means of 4.0 points favoring esketamine at day 28 (SE 1.69). An earlier phase 2 dose-finding trial showed a similar adjunctive benefit. On this evidence esketamine (Spravato) received regulatory approval for treatment-resistant depression, given under medical supervision because of dissociation and transient blood-pressure rises.
The studies · 2
Popova et al., efficacy and safety of flexibly dosed esketamine nasal spray in treatment-resistant depression · Am J Psychiatry 2019;176:428-438
Daly et al., efficacy and safety of intranasal esketamine adjunctive to oral antidepressant therapy in treatment-resistant depression · JAMA Psychiatry 2018;75:139-148
Microdosing matched placebo, with no clear benefit for well-being in the largest self-blinded trial
In the largest placebo-controlled test of microdosing, the people who microdosed felt better, but so did the placebo group, and the two did not differ. The apparent gains tracked with people guessing which they had taken.
This self-blinding citizen-science study had 191 participants build placebo control into their own microdosing routine over four weeks without clinical supervision, making it the largest placebo-controlled trial of psychedelics to date. All psychological outcomes improved from baseline in the microdose group, but the placebo group improved too, with no significant between-group differences. Small acute and post-acute differences (emotional state, drug intensity, mood, energy, creativity, and anxiety) were explained by participants breaking blind and correctly identifying whether they had taken a microdose or placebo.
The study · 1
Szigeti et al., self-blinding citizen science to explore psychedelic microdosing · eLife 2021;10:e62878
One 25 mg psilocybin dose eased treatment-resistant depression 6.6 points more than a low dose at three weeks
A single high dose of psilocybin, given with therapy, eased treatment-resistant depression more than a tiny comparison dose after three weeks. The improvement had faded by twelve weeks, and side effects were common.
This phase 2b trial (COMP360) randomized 233 people with treatment-resistant depression to a single 25 mg, 10 mg, or 1 mg dose of synthetic psilocybin alongside psychological support. Mean MADRS change at three weeks was -12.0 (25 mg), -7.9 (10 mg), and -5.4 (1 mg). The 25 mg versus 1 mg difference was -6.6 (95% CI -10.2 to -2.9, P<0.001); the 10 mg versus 1 mg difference was not significant. Response and remission at three weeks favored 25 mg, but the advantage was not sustained at twelve weeks. Adverse events occurred in 179 of 233 participants (77%), including headache, nausea, and dizziness, and suicidal behavior was reported in some participants.
The study · 1
Goodwin et al., single-dose psilocybin for a treatment-resistant episode of major depression · N Engl J Med 2022;387:1637-1648
Two psilocybin sessions with therapy cut major-depression scores sharply, with 54% in remission at four weeks
Two psilocybin sessions with therapy produced a large short-term improvement in major depression, with about half of a small group in remission a month later.
This Johns Hopkins trial randomized 27 adults with major depressive disorder (24 completed; mean age 40; 67% women) to immediate psilocybin therapy or a delayed-treatment waiting list. Two psilocybin sessions with supportive therapy produced large reductions on the GRID-HAMD (Cohen d 2.5 at week 5 and 2.6 at week 8). At week 4, 71% met response (>=50% reduction) and 54% met remission (score <=7). The comparison was against a waiting list, which does not control for time, attention, or expectation.
The study · 1
Davis et al., effects of psilocybin-assisted therapy on major depressive disorder, a randomized clinical trial · JAMA Psychiatry 2021;78:481-489
Psilocybin did not clearly beat a standard antidepressant on the main depression measure at six weeks
When psilocybin was tested head-to-head against a standard antidepressant, the two came out about even on the main measure of depression. Some secondary measures leaned toward psilocybin, but the study was too small to decide.
This double-blind phase 2 trial randomized 59 people with depression to psilocybin (two 25 mg doses three weeks apart) or six weeks of daily escitalopram, both with psychological support. The primary outcome, change in QIDS-SR-16 at six weeks, showed no significant between-group difference (-2.0 points, 95% CI -5.0 to 0.9, P=0.17). Secondary measures such as QIDS-SR-16 response (70% vs 48%) and remission (57% vs 28%) favored psilocybin, but the trial was not powered for them and had no placebo-only arm.
The study · 1
Carhart-Harris et al., trial of psilocybin versus escitalopram for depression · N Engl J Med 2021;384:1402-1411
A single psilocybin session eased cancer-related distress, with 60 to 80% still improved at about six months
For people facing life-threatening cancer, a single psilocybin session with support eased depression and anxiety, and most were still better roughly six months later.
A Johns Hopkins crossover trial (51 patients) and an NYU crossover trial (29 patients) each gave people with cancer-related depression and anxiety a single moderate-to-high psilocybin dose with psychological support, compared with a very low dose or an active control. Both produced immediate, substantial, and sustained decreases in depressed mood and anxiety alongside increases in quality of life and sense of meaning; at roughly six months, 60 to 80% of participants still showed clinically significant improvement.
The studies · 2
Griffiths et al., psilocybin produces substantial and sustained decreases in depression and anxiety in patients with life-threatening cancer · J Psychopharmacol 2016;30:1181-1197
Ross et al., rapid and sustained symptom reduction following psilocybin treatment for anxiety and depression in patients with life-threatening cancer · J Psychopharmacol 2016;30:1165-1180
Anxiety And Stress
MDMA-assisted therapy lowered PTSD severity more than therapy alone across two phase 3 trials
In two large trials, MDMA given alongside structured therapy lowered PTSD symptoms more than the same therapy with a placebo. The effect was moderate to large.
The MAPP1 trial (n=90) randomized people with severe PTSD to MDMA or placebo, each with three preparatory and nine integrative therapy sessions. CAPS-5 severity fell by a mean 24.4 points with MDMA versus 13.9 with placebo (P<0.0001, d 0.91). The confirmatory MAPP2 trial (n=104, moderate to severe PTSD) again favored MDMA-assisted therapy on CAPS-5 (P<0.001, d 0.7). Both were well tolerated with no deaths or serious drug-related adverse events reported.
The studies · 2
Mitchell et al., MDMA-assisted therapy for severe PTSD, a randomized double-blind placebo-controlled phase 3 study · Nat Med 2021;27:1025-1033
Mitchell et al., MDMA-assisted therapy for moderate to severe PTSD, a randomized placebo-controlled phase 3 trial · Nat Med 2023;29:2473-2480
Evidence And Methods
Patients can tell what they got more than 90% of the time, and the FDA declined MDMA for PTSD in 2024
Because these drugs produce obvious effects, people in the studies can usually tell whether they got the active drug, which makes the benefit hard to separate from expectation. Partly for this reason, the FDA did not approve MDMA therapy for PTSD in 2024 and asked for another trial.
A systematic review of blinding integrity in psychedelic RCTs found that only 29.5% of trials even assessed blinding, while 57.1% named it as a limitation. Where it was measured, functional unblinding was substantial: psilocybin, LSD, and ayahuasca studies frequently reported blinding failure above 90% among both participants and raters, and inert-placebo MDMA trials exceeded 85%. A 2026 reassessment of the MDMA-for-PTSD program reached the same conclusion, that difficulties in blinding and expectation effects limit how firmly the benefit can be attributed to the drug. In 2024 the FDA declined to approve MDMA-assisted therapy for PTSD and requested an additional trial, citing trial-design, blinding, and conduct concerns.
The studies · 2
Blinding integrity in psychedelic randomized clinical trials, a systematic review · JAMA Psychiatry 2026
From therapeutic promise to evidentiary discipline, reassessing MDMA-assisted psychotherapy for PTSD · J Trauma Stress 2026
How it works
Classic psychedelics act on the 5-HT2A serotonin receptor, MDMA releases serotonin, ketamine blocks NMDA
The classic psychedelics act on one serotonin receptor (5-HT2A). MDMA floods the brain with serotonin instead, and ketamine acts on a different system entirely, so grouping them together is loose.
Comprehensive pharmacology reviews establish that the subjective effects of classic psychedelics depend on agonism at the serotonin 5-HT2A receptor: blocking that receptor blocks the experience. This is thought to increase the flexibility of cortical activity and reduce the grip of rigid, self-referential thinking, a mechanism of interest for depression and end-of-life distress. MDMA is an entactogen that chiefly releases serotonin (and dopamine and noradrenaline) rather than acting as a 5-HT2A agonist, producing empathy and reduced fear that are used to support trauma processing. Ketamine and its enantiomer esketamine are dissociatives that antagonize the NMDA glutamate receptor, a distinct pathway with rapid antidepressant effects.
The study · 1
Nichols, psychedelics, a comprehensive pharmacology review · Pharmacol Rev 2016;68:264-355
How It Works
The classic psychedelics share a single core mechanism. Their effects depend on activating the serotonin 5-HT2A receptor, which appears to increase the flexibility of activity across the cortex and temporarily loosen the fixed, self-referential thinking that runs through depression and rumination. The idea behind the therapy is that a person can revisit thoughts, memories, and feelings from a different vantage point while well supported, and that the change can outlast the drug. MDMA works by lowering fear and raising trust, so that traumatic material becomes bearable to process. Ketamine and esketamine act on glutamate instead of serotonin and lift mood quickly, which is why they are used when a fast effect matters.
These drugs produce unmistakable subjective effects, so in a trial almost everyone can tell whether they received the active drug or the placebo. This is called functional unblinding, and a systematic review found it is pervasive: in psilocybin studies, participants and raters correctly identified who got the drug more than 90 percent of the time. When people know they received a treatment they hoped would work, expectation can improve their scores, and that expectation is very difficult to separate from the drug. This does not mean the benefit is absent.
It means the measured size of the effect is likely inflated, and the true effect is not yet established.
The Legal Position
The law and the science are not in the same place. In the United States:
- The classic psychedelics (psilocybin, LSD, DMT) and MDMA are Schedule I federally, the most restricted category, so outside an authorized research or approved-treatment setting their use is illegal.
- Esketamine is the one exception, approved and prescribed under supervision.
- Oregon and Colorado have created state-regulated frameworks for supervised adult psilocybin use, legal under state law but not under the federal classification.
Elsewhere the compounds remain investigational, reachable only inside clinical trials and expanded-access programs. None of this page is a route to obtaining these substances; it is a description of where the law currently stands.
Go Deeper
- Depression: what actually helps: the full picture of treatments for depression, where psilocybin and esketamine sit among the better-established options.
- Anxiety: the condition that runs alongside much of this research, and the treatments with the strongest track record.
- Meditation and mindfulness: a low-risk way to work with a scattered or anxious mind that you can start on your own, and the grounding practice the Chinese medicine view points to first.
- Purpose and meaning: the sense of meaning that psilocybin trials in end-of-life distress kept measuring, approached as a practice in its own right.
The Chinese Medicine View
Chinese medicine has a long-standing frame for altered states of mind, and it leans toward caution. The Heart is said to house the Shen, the spirit or consciousness, and clear thought, steady emotion, and restful sleep are read as signs of a settled Shen. A mind flooded, disoriented, or thrown into fear or agitation is described as a disturbance of the Shen, and the classical tradition treats such disturbance as something to calm and anchor. The bias of the medicine is toward grounding: settling the Shen, harmonizing the Heart and Liver, and rooting a scattered mind back in the body through stillness, breath, and regular life.
Read through that lens, an intense, mind-altering experience is not neutral. It could be seen as deliberately stirring the Shen, which the tradition would approach with great care, especially in someone already depleted, agitated, or unsettled, and especially without skilled support and a calm setting. This is an interpretation, not a verdict, and not a claim that the tradition anticipated modern trials. It is offered because it lines up, in its own language, with what the clinical evidence keeps showing: that preparation, support, and a stable state shape the outcome, and that a fragile person is the one most likely to be harmed. The wider preventive tradition of Yang Sheng, nourishing life, would place the emphasis on grounding practices first.
Cautions For This Practice
Everything to be aware of is here, in one place. This practice suits most healthy people; a few situations call for real care.
In unsupervised use, 11% recalling a bad trip put themselves or others at risk of physical harm
An online survey asked people (78% male, mean age around 30) about the single most psychologically difficult experience of their life with psilocybin mushrooms. Eleven percent reported putting themselves or others at risk of physical harm, 2.6% behaved aggressively, and 2.7% sought medical help; of those whose experience was more than a year earlier, 7.6% had sought treatment for enduring symptoms. Difficulty, dose, and the absence of physical comfort and social support all raised the likelihood of risk. Despite the difficulty, 84% still reported benefiting from the experience overall.Carbonaro et al., survey study of challenging experiences after ingesting psilocybin mushrooms
Psychedelics triggered mania in 5.8% to 30% of people and can provoke psychosis in the vulnerable
The meta-analysis pooled controlled trials and naturalistic studies. Rates of dysphoria, hypomania, or mania ran from 5.8% in controlled psilocybin-assisted therapy trials for depression up to 30% in naturalistic use among people with bipolar spectrum conditions. The pooled rate of subsequent transition to a bipolar diagnosis was 4% (95% CI 2 to 8%, N=7478), with little evidence of a hallucinogen-specific signal. A separate narrative review of psychedelics and schizophrenia spectrum disorders concludes they may trigger psychosis in vulnerable individuals, while noting the magnitude of that risk is inadequately quantified.Psychedelic-induced hypomania and mania, a systematic review and meta-analysisThe intersection between psychedelics and schizophrenia spectrum disorders, reevaluating risk and therapeutic potential
Repeated dosing touches the 5-HT2B receptor tied to heart-valve damage, a risk not yet measured
Valvular heart disease from drugs such as fenfluramine and certain dopamine agonists is driven by activation of the serotonin 5-HT2B receptor on heart valves. A pharmacology analysis found that LSD, psilocybin metabolites, and MDMA are partial agonists at 5-HT2B, with potencies generally lower than established valvulopathogens but not without potential risk. No animal or clinical study appropriately designed to measure valve outcomes from repeated or microdosed use has been done, so this remains a mechanistic concern, not a measured rate.Tagen et al., the risk of chronic psychedelic and MDMA microdosing for valvular heart disease
Mixing a classic psychedelic with lithium brought on seizures in 47% of reported cases
Researchers analyzed self-reported online accounts of combining a classic psychedelic with a mood stabilizer. Of 62 lithium-plus-psychedelic reports, 47% involved seizures, an additional 18% involved a bad trip, and 39% involved a need for medical attention; of 34 lamotrigine-plus-psychedelic reports, none involved seizures. The authors conclude the combination may pose a significant seizure risk for people taking lithium.Nayak et al., classic psychedelic coadministration with lithium, but not lamotrigine, is associated with seizures
A minority develop lasting visual disturbances (HPPD) after use, uncommon but long documented
Hallucinogen persisting perception disorder is a documented condition in which visual phenomena such as trails, halos, or afterimages persist after psychedelic use, sometimes for a long time. A review covering 50 years of reports found the condition is real but its rate cannot be reliably estimated from the scattered case literature; it is more often described with repeated or heavy use than with a single supervised session.Halpern and Pope, hallucinogen persisting perception disorder, what do we know after 50 years
These are not everyday-safe drugs, and this is not a guide to using them
This page is education about the research, the law, and the risks. It carries no dosing, no sourcing, and no instructions for use. Most use outside an approved-treatment or research setting is illegal in most places, and unsupervised use carries psychological and medical risk. The clinical results come from screened patients in prepared sessions with trained support, which is a very different situation from taking a substance alone.
Interactions with other medicines
Serotonin-based antidepressants (SSRIs and SNRIs) can blunt the effect of classic psychedelics, and combining serotonergic drugs, including MDMA, with an MAOI antidepressant can push serotonin to dangerous levels. Combining a classic psychedelic with lithium has been linked to seizures, covered in the research above. Anyone on psychiatric medication is in a situation where these interactions can be dangerous, and a prescribing clinician is the right person to consult.
Set, setting, and supervision
The research repeatedly points to the same thing: preparation, a calm and safe environment, and skilled support shape how an experience goes. In the survey evidence above, difficulty and risk rose at higher doses and when support and physical comfort were absent. The phrase the field uses is set, setting, and supervision, and it separates the studied conditions from unsupervised use.
Psychedelics are a promising area of research, and they are potent drugs whose risks depend heavily on the person, the dose, and the setting. The stance here is to inform: read the evidence at its true strength, take the risks seriously, and, for anything touching your own care or medication, talk it through with a qualified clinician.
Common Questions
Are psychedelics legal?
Mostly not, and the law lags well behind the research. In the United States the classic psychedelics and MDMA are Schedule I federally, so their use outside an authorized research or approved-treatment setting is illegal. The exception is esketamine, which is approved and given in a certified clinic. Oregon and Colorado have created state-regulated frameworks for supervised adult psilocybin use, legal under state law but not under federal law. In most other places the compounds are investigational, reachable through clinical trials, not by prescription. This page describes where the law stands and is not a way to obtain anything.
Is this a settled treatment I can get?
For the classic psychedelics and MDMA, not yet. The trial results are promising and early, and outside a clinical trial or an approved program these are still investigational. The one treatment in this group with regulatory approval is esketamine for treatment-resistant depression, which a psychiatrist can prescribe and supervise. If you are drawn to this research because standard treatments have not worked, the productive step is a conversation with a mental-health clinician about the options that do exist, including trials you may be eligible for.
What is the difference between psilocybin, MDMA, and ketamine?
They are three different kinds of drug that get grouped together loosely. Psilocybin is a classic psychedelic that acts on the serotonin 5-HT2A receptor and is studied for depression and end-of-life distress. MDMA is an entactogen that works by releasing serotonin, lowering fear and raising trust, and is studied for PTSD. Ketamine and esketamine are dissociatives that act on the NMDA glutamate receptor, work quickly on mood, and are the ones with regulatory approval. Same broad conversation, different pharmacology and different evidence.
Does microdosing work?
The best test to date says the benefit does not survive a placebo control. In the largest placebo-controlled study of microdosing, people who took small regular doses improved on every psychological measure, but the placebo group improved just as much, and the two groups did not differ. The small differences that did appear tracked with people correctly guessing whether they were on the drug. Anecdotes about microdosing are common and sincere, and this study suggests much of the effect is expectation.
Why did the FDA decline MDMA if the trials worked?
Because a positive trial and a convincing one are not always the same thing. The two phase 3 MDMA trials did show benefit, but regulators pointed to problems that make the size of that benefit hard to trust: nearly everyone could tell whether they got the drug or the placebo, so expectation is tangled up with the effect, and there were questions about trial conduct and about how long the improvement lasts. In 2024 the FDA declined to approve MDMA-assisted therapy for PTSD and asked for another trial. It is a statement about the strength of the evidence, not a claim that the treatment does nothing.
Who should be especially careful?
The risks fall hardest on specific people, and they are the reason screening exists in the trials. A personal or family history of bipolar disorder or of psychosis is the most important, because these drugs can trigger mania or, in vulnerable people, psychosis. Anyone taking lithium, an MAOI, or a serotonergic antidepressant is in interaction territory that can be dangerous. Heart-valve concerns attach mainly to frequent or repeated dosing. And a person who is currently very unsettled or unsupported is the one the evidence suggests is most likely to have a difficult experience. All of these sit in the cautions section above, with their sources.
Explore Related
Other pages this one connects to, by the evidence they share, the outcomes they touch, and the ground they cover.
All 19 sources on this page independently checked and cross-referenced.
Thomas Dehli, Founder & Editor, Sacred Lotus
Sacred Lotus has published Chinese medicine reference material since 2001. Integrative pages are held to the same standard as the herb and formula library: cite the source, grade the claim at its real strength, and say where the research has not looked. This page is educational and it is not medical advice. Last reviewed and updated August 10, 2026.
Evidence strength
How confidently the research supports a claim. Strength describes the evidence, not our endorsement.