What Is Psilocybin? How ‘Magic Mushrooms’ Are Being Studied for Mental Health Treatment

For decades, psilocybin—the psychoactive compound found in certain species of mushrooms—was primarily known for its use as a recreational psychedelic. But a wave of rigorous clinical research is changing that narrative.

Studies from institutions like Johns Hopkins University, Imperial College London, and others suggest that psilocybin, when administered in controlled therapeutic settings, may help treat conditions like treatment-resistant depression (TRD), anxiety, post-traumatic stress disorder (PTSD), and substance use disorders.^1,2,3

While psilocybin remains a Schedule I controlled substance under federal law, its designation as a “breakthrough therapy” by the FDA for treatment-resistant depression (as announced by COMPASS Pathways for its psilocybin therapy) and growing legalization efforts signal a shift in how we understand psychedelic medicine.⁴

Here’s what the science says about psilocybin, how it works, and what its therapeutic potential might mean for mental health treatment.

What Exactly Is Psilocybin and What Does It Do?

Psilocybin is a naturally occurring psychedelic compound found in more than 200 species of mushrooms, primarily in the Psilocybe genus. These fungi grow in warm, humid environments across the globe—on every continent except Antarctica—where decomposing plant material provides ideal conditions.

When consumed, psilocybin-containing mushrooms (also known as “magic mushrooms”) are converted in the body to psilocin, which acts on serotonin receptors in the brain.^5,6 This interaction produces altered perception, changes in mood and cognition, and—in therapeutic contexts—what researchers describe as profound shifts in consciousness that may facilitate emotional processing and psychological insight.^7,8

It’s important to distinguish between recreational use and therapeutic use. In clinical settings, psilocybin is administered at carefully calibrated doses under professional supervision, often alongside psychotherapy. This structured approach is designed to maximize potential benefits while minimizing risks.

How Psilocybin Affects the Brain

Psilocybin’s effects stem from its interaction with serotonin receptors in the brain, particularly the 5‑HT2A receptor (a specific serotonin receptor involved in perception, mood, and cognition).^5,6 Structurally similar to serotonin—a neurotransmitter involved in mood regulation, perception, and cognition—psilocybin (via its active metabolite, psilocin) engages these receptors and alters neural activity; antagonist studies support 5‑HT2A’s central role.^5,6

Neuroimaging studies show that psilocybin temporarily alters large‑scale brain networks, including decreased connectivity within the default mode network (DMN)—a set of brain regions most active during self‑focused thought and mind‑wandering with increased global integration.^7,9 In depression, overactivity and rigid coupling within the DMN have been linked to rumination and negative self‑referential thinking. Transiently reducing DMN integrity may help loosen these patterns and open a window for new cognitive–emotional processing.^7,9 Consistent with this, imaging markers of altered network dynamics correlate with subjective experience and symptom improvement in major depressive disorder (MDD) following psilocybin‑assisted therapy.^8,10

Additionally, emerging evidence suggests psilocybin may promote neuroplasticity (the brain’s ability to change by forming new connections), which could support longer‑term changes in mood and behavior when paired with psychotherapy.5,9

What to Expect from Taking Psilocybin

In clinical settings, psilocybin is typically administered orally in capsule form at controlled doses. Effects generally begin 30–45 minutes after ingestion, peak around 2–3 hours, and last 4–6 hours total, though individual experiences vary.

The subjective effects of psilocybin can include:

Perceptual changes. Visual and auditory perception may be altered—colors may appear more vivid, patterns may seem to shift or breathe, and sounds may feel more immersive. These changes are dose-dependent and generally not distressing in a supportive environment.

Altered sense of self. Psilocybin can temporarily reduce the sense of boundaries between self and surroundings, a phenomenon sometimes called “ego dissolution.” In therapeutic contexts, this experience is thought to help people gain new perspectives on entrenched patterns of thinking or feeling.

Emotional intensity. People often report experiencing a wide range of emotions during a psilocybin session—from joy and connection to sadness or fear. Skilled therapists help guide participants through these experiences, which can facilitate emotional breakthroughs.

Mystical or transcendent experiences. Some people describe feelings of unity, sacredness, or profound insight. Research suggests that the intensity of these experiences may correlate with therapeutic outcomes, particularly in treatment of depression and existential distress.^11,12

Safety Profile and Risks

Psilocybin has a relatively favorable safety profile compared to many other psychoactive substances.^1,3,13 There are no documented cases of fatal overdose from psilocybin alone.¹⁴ However, it is not without risks.

Physical effects may include nausea, increased heart rate, sweating, and dizziness—particularly during the onset of effects. These are generally mild and temporary.

Psychological risks are more significant. Psilocybin can trigger intense anxiety, confusion, or panic, especially in unsupervised or unpredictable settings.^13,15 In rare cases, it may precipitate acute psychotic episodes, particularly in individuals with a personal or family history of psychotic disorders such as schizophrenia.^15,16

Contraindications include:

• Personal or family history of psychosis or bipolar disorder¹⁶
• Use of certain medications (especially SSRIs, MAOIs, or other serotonergic drugs)—these are often excluded in trials, and potential interactions warrant clinical caution¹
• Pregnancy or breastfeeding (insufficient safety data; these groups are typically excluded from trials)¹
• Cardiovascular conditions (psilocybin can temporarily elevate heart rate and blood pressure)^1,2

In clinical trials, adverse events are rare when participants are carefully screened and sessions are conducted with trained facilitators in controlled environments.^1,2,3 This underscores the importance of context: therapeutic use under medical supervision differs significantly from uncontrolled recreational use.

Addiction Potential

Psilocybin is not considered physically addictive. Repeated use over short intervals appears to blunt psilocybin’s effects, which naturally discourages frequent use.

While psychological dependence is theoretically possible with any substance, psilocybin’s effects—intensity, unpredictability, and the need for recovery time—make habitual use uncommon. Some studies even suggest psilocybin may help treat substance use disorders, including alcohol and tobacco dependence.^17,18

Psilocybin-Assisted Therapy: What the Research Shows

Psilocybin-assisted therapy typically involves one to three supervised dosing sessions combined with preparatory meetings and integration therapy afterward. During sessions, participants take a measured dose of psilocybin in a calm, supportive environment with trained therapists present. The goal is not simply to induce a psychedelic experience, but to use that experience as a catalyst for therapeutic change.

Depression

Multiple randomized controlled trials have shown that psilocybin, combined with psychological support, produces rapid and sustained reductions in depression symptoms—including in treatment-resistant cases.^1,2,3 A 2021 study found psilocybin therapy comparable to escitalopram (a common SSRI) for major depressive disorder, with some participants showing greater improvement.¹⁹

Anxiety and Existential Distress

Studies in patients with life-threatening cancer diagnoses found that a single psilocybin session significantly reduced anxiety and depression, with benefits lasting months to years in many participants.^20,21

Substance Use Disorders

Preliminary research suggests psilocybin may help treat alcohol use disorder and tobacco dependence, possibly by facilitating motivation for change and disrupting ingrained behavioral patterns.^17,18

PTSD and Other Conditions

Ongoing trials are exploring psilocybin’s potential for PTSD, eating disorders, obsessive-compulsive disorder (OCD), and other conditions.^18,22,23

Psilocybin therapy is not FDA‑approved and remains accessible only through clinical trials or in limited state programs.

If you’re experiencing depression, anxiety, or other mental health concerns, evidence-based treatments—including psychotherapy and FDA-approved medications—are commonly recommended treatments. Speak with a licensed mental health provider about your options.

Legal Status: A Shifting Landscape

Under federal law, psilocybin remains a Schedule I controlled substance, classified as having “no accepted medical use” and high potential for abuse.²⁴

However, the legal landscape is changing rapidly:

State‑regulated services

In Oregon and Colorado, psilocybin is available under state‑regulated services, not prescriptions. Adults can access facilitator‑supported sessions in licensed centers; there are no take‑home prescriptions or over‑the‑counter sales.

• Oregon (2020): Measure 109 legalized psilocybin services in licensed facilities, with the first centers opening in 2023.

• Colorado (2022): Voters approved Proposition 122, which decriminalized personal use/possession and created a framework for regulated, facilitator‑supported psilocybin services.

Decriminalization

More than a dozen U.S. cities (e.g., Denver; Oakland; Seattle; Washington, D.C.) have made adult personal use/possession a low law‑enforcement priority, however decriminalization does not allow retail sales or broad legal use.

International context

• Canada has granted exemptions for end‑of‑life psilocybin services (Health Canada Special Access Program).²⁵

• Australia rescheduled psilocybin in 2023 to allow authorized psychiatric use (TGA, 2023).²⁶

Is psilocybin legal?

In the U.S., psilocybin remains illegal under federal law (Schedule I). Some cities have decriminalized personal possession—meaning enforcement priority is lowered—but this does not allow retail sales or broad legal use. Oregon and Colorado offer state‑regulated, facilitator‑supported services in licensed centers, not prescriptions or take‑home products. Outside these programs and FDA‑regulated research, possession, sale, and distribution are illegal, and penalties vary by state.²⁴

What’s Next for Psilocybin Therapy?

The momentum behind psilocybin research shows no signs of slowing. As of 2024, late-stage clinical trials are underway. Companies are leading efforts to bring psilocybin therapy to market as a prescription treatment for depression and other conditions (ClinicalTrials.gov: NCT05711940; NCT03775200).^27,28

If these trials succeed, psilocybin could become the first FDA‑approved psychedelic medicine in the U.S.

Key questions remain:

• How do we ensure equitable access to psilocybin therapy?
• What training and oversight will be required for providers?
• How will insurance cover these treatments?
• What are the long-term outcomes for patients who undergo psilocybin therapy?

While challenges remain, the research to date suggests that psilocybin—used responsibly within a therapeutic framework—may offer meaningful relief for people who haven’t responded to conventional treatments.

If you’re struggling with mental health challenges, current evidence-based options include psychotherapy (such as cognitive-behavioral therapy or EMDR), FDA-approved medications, and lifestyle interventions. A licensed mental health provider can help you explore what’s right for you. If you’re interested in psilocybin therapy specifically, ask about clinical trials or—if you’re in Oregon or Colorado—legal therapeutic programs.

References

1. Goodwin, G. M., Aaronson, S. T., Alvarez, O., et al. (2022). Single-Dose Psilocybin for a Treatment-Resistant Episode of Major Depression. The New England Journal of Medicine, 387( 1637–1648. https://doi.org/10.1056/NEJMoa2206443
2. Goodwin, G. M., Aaronson, S. T., Alvarez, O., et al. (2023). Single-dose psilocybin for a treatment-resistant episode of major depression: Impact on patient-reported depression severity, anxiety, function, and quality of life. Journal of Affective Disorders. https://doi.org/10.1016/j.jad.2023.01.108
3. Raison, C. L., Sanacora, G., Woolley, J. D., et al. (2023). Single-Dose Psilocybin Treatment for Major Depressive Disorder: A Randomized Clinical Trial. JAMA. https://doi.org/10.1001/jama.2023.14530
4. COMPASS Pathways. (2018). COMPASS Pathways receives FDA Breakthrough Therapy designation for psilocybin therapy for treatment-resistant depression. Investor Relations. https://ir.compasspathways.com/News–Events-/news/news-details/2018/COMPASS-Pathways-receives-FDA-Breakthrough-Therapy-designation-for-psilocybin-therapy-for-treatment-resistant-depression/default.aspx. Accessed March 2026.
5. Adebo, M., Bonnet, M., Laouej, O., Defaix, C., McGowan, J., Butlen‑Ducuing, F., David, D., Poupon, E., Tritschler, L., & Gardier, A. (2025). Psilocybin as Transformative Fast‑Acting Antidepressant: Pharmacological Properties and Molecular Mechanisms. Fundamental & Clinical Pharmacology, 39. https://doi.org/10.1111/fcp.70038
6. Gobbi, G. (2024). CCNP Innovations in Neuropsychopharmacology Award. Journal of Psychiatry & Neuroscience, 49, E301–E318. https://doi.org/10.1503/jpn.240037
7. Yu, Z., Burback, L., Winkler, O., Xu, L., Dennett, L., Vermetten, E., Greenshaw, A., Li, X., Milne, M., Wang, F., Cao, B., Winship, I., Zhang, Y., & Chan, A. (2024). Alterations in brain network connectivity and subjective experience induced by psychedelics: a scoping review. Frontiers in Psychiatry, 15. https://doi.org/10.3389/fpsyt.2024.1386321
8. Sabbah, S., Li, S., Wong, S., Le, G., Badulescu, S., Hawco, C., Rosenblat, J., & McIntyre, R. (2025). Temporal dynamics in neuroimaging as correlates of therapeutic response to psilocybin in major depressive disorder: A systematic review and critical appraisal. Journal of Affective Disorders, 120335. https://doi.org/10.1016/j.jad.2025.120335
9. Liebnau, J., Betzler, F., & Kerber, A. (2025). Catalyst for change: Psilocybin’s antidepressant mechanisms—A systematic review. Journal of Psychopharmacology, 39, 397–415. https://doi.org/10.1177/02698811241312866
10. Wong, S., Jones, B., Thiyagarajah, M., Sabbah, S., Thompson, C., Solmi, M., Umer, M., Zrenner, C., Voineskos, D., Rosenblat, J., Mulsant, B., Blumberger, D., & Husain, M. (2025). Biological markers of treatment response to serotonergic psychedelic therapies: a systematic review. Therapeutic Advances in Psychopharmacology, 15. https://doi.org/10.1177/20451253251384513
11. Goodwin, G., Aaronson, S., Alvarez, O., Carhart-Harris, R., Chai-Rees, J., Croal, M., Debattista, C., Dunlop, B., Feifel, D., Hellerstein, D., Husain, M., Kelly, J., Kirlić, N., Licht, R., Marwood, L., Meyer, T., Mistry, S., Nowakowska, A., Páleníček, T., Repantis, D., Schoevers, R., Simmons, H., Somers, M., Teoh, E., Tsai, J., Wahba, M., Williams, S., Young, A., Young, M., Zisook, S., & Malievskaia, E. (2024). The role of the psychedelic experience in psilocybin treatment for treatment-resistant depression.. Journal of affective disorders, 372, 523-532. https://doi.org/10.1016/j.jad.2024.12.061
12. Haijen, E., Kaelen, M., Roseman, L., Timmermann, C., Kettner, H., Russ, S., Nutt, D., Daws, R., Hampshire, A., Lorenz, R., & Carhart-Harris, R. (2018). Predicting Responses to Psychedelics: A Prospective Study. Frontiers in Pharmacology, 9. https://doi.org/10.3389/fphar.2018.00897
13. Kopra, E., Ferris, J., Winstock, A., Young, A., & Rucker, J. (2022). Adverse experiences resulting in emergency medical treatment seeking following the use of magic mushrooms. Journal of Psychopharmacology, 36, 965–973. https://doi.org/10.1177/02698811221084063
14. Wagner, S., Thornton, S., Oller, L., & Hudson, M. (2021). Wild mushroom exposures in Kansas, 2013–2018. Toxicology Communications, 5, 76–81. https://doi.org/10.1080/24734306.2021.1893972
15. Carbonaro, T. M., Bradstreet, M. P., Barrett, F. S., MacLean, K. A., Jesse, R., Johnson, M. W., & Griffiths, R. R. (2016). Survey study of challenging experiences after ingesting psilocybin mushrooms: Acute and enduring positive and negative consequences. Journal of Psychopharmacology, 30(12), 1268–1278. https://doi.org/10.1177/0269881116662634
16. Morton, E., Sakai, K., Ashtari, A., Pleet, M., Michalak, E., & Woolley, J. (2022). Risks and benefits of psilocybin use in people with bipolar disorder: An international web-based survey on experiences of ‘magic mushroom’ consumption. Journal of Psychopharmacology, 37, 49–60. https://doi.org/10.1177/02698811221131997
17. Johnson, M. W., Garcia-Romeu, A., Johnson, P. S., & Griffiths, R. R. (2017). An online survey of tobacco smoking cessation associated with naturalistic psychedelic use. Journal of Psychopharmacology, 31(7), 841–850. https://doi.org/10.1177/0269881116684335
18. Nayak, S. M., Jackson, H., Sepeda, N. D., et al. (2023). Naturalistic psilocybin use is associated with persisting improvements in mental health and wellbeing: results from a prospective, longitudinal survey. Frontiers in Psychiatry, 14, 1199642. https://doi.org/10.3389/fpsyt.2023.1199642
19. Carhart‑Harris, R. L., Giribaldi, B., et al. (2021). Trial of psilocybin versus escitalopram for depression. The New England Journal of Medicine, 384(15), 1402–1411. https://doi.org/10.1056/NEJMoa2032994
20. Griffiths, R. R., Johnson, M. W., et al. (2016). Psilocybin produces substantial and sustained decreases in depression and anxiety in patients with life‑threatening cancer: A randomized double‑blind trial. Journal of Psychopharmacology, 30(12), 1181–1197. https://doi.org/10.1177/0269881116675513
21. Ross, S., Bossis, A., et al. (2016). Rapid and sustained symptom reduction following psilocybin treatment for anxiety and depression in patients with life‑threatening cancer: A randomized controlled trial. Journal of Psychopharmacology, 30(12), 1165–1180. https://doi.org/10.1177/0269881116675512
22. Modlin, N., L., M., Sarang, M., et al. (2025). Perspectives on Trauma Treatment, Self-Management Strategies, and Attitudes Toward Psychedelic Therapies in Individuals with Psychological Trauma Symptoms. Psychiatry and Clinical Psychopharmacology, 35(S1), S3–S19. https://doi.org/10.5152/pcp.2025.24934
23. Kopra, E., Ferris, J. A., Winstock, A. R., Kuypers, K. P. C., Young, A. H., & Rucker, J. J. H. (2023). Investigation of self-treatment with lysergic acid diethylamide and psilocybin mushrooms: Findings from the Global Drug Survey 2020. Journal of Psychopharmacology, 37(6), 733–748. https://doi.org/10.1177/02698811231158245
24. Electronic Code of Federal Regulations (eCFR). 21 CFR Part 1308—Schedules of Controlled Substances (Schedule I listing includes psilocybin). https://www.ecfr.gov/current/title-21/chapter-II/part-1308. Accessed March 2026.
25. Health Canada. Special Access Program (SAP) for drugs. https://www.canada.ca/en/health-canada/services/drugs-health-products/special-access-drugs.html. Accessed March 2026.
26. Therapeutic Goods Administration (TGA). Re-scheduling of psilocybin and MDMA: Questions and answers (Final decision). https://www.tga.gov.au/resources/publication/scheduling-decisions-final/notice-final-decision-amend-or-amend-current-poisons-standard-june-2022-acms-38-psilocybine-and-mdma/re-scheduling-psilocybin-and-mdma-poisons-standard-questions-and-answers. Accessed March 2026.
27. ClinicalTrials.gov. The Safety and Efficacy of Psilocybin in Participants With Treatment Resistant Depression (P-TRD). Sponsor: COMPASS Pathways. Phase 2; Completed. Primary outcome: change in MADRS from baseline to Week 3. ClinicalTrials.gov Identifier: NCT03775200. https://clinicaltrials.gov/study/NCT03775200. Accessed March 2026.
28. ClinicalTrials.gov. Efficacy, Safety, and Tolerability of Two Administrations of COMP360 in Participants With TRD. Sponsor: COMPASS Pathways. Status: Active, not recruiting; multi‑part design with follow‑up to 52 weeks. ClinicalTrials.gov Identifier: NCT05711940. https://clinicaltrials.gov/study/NCT05711940. Accessed March 2026.