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© 2026 PsyBear · psybear.co

Made with ♥ in Northern California

Disclaimer: PsyBear provides educational information only. We do not sell, distribute, or encourage the illegal use of controlled substances. Psilocybin remains Schedule I federally. Oregon and Colorado have state-licensed supervised psilocybin programs as of 2026.

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Glossary5-HT2B receptor

5-HT2B receptor

A serotonin receptor subtype expressed in cardiovascular tissue, the gastrointestinal system, and the trigeminal system. Distinct from the 5-HT2A receptor that mediates psilocybin's psychedelic and antidepressant effects. 5-HT2B and 5-HT2C agonism may mediate psilocybin's preventive effects on cluster headaches and migraines at sub-psychedelic doses — explaining why therapeutic headache benefits occur independently of the intensity of the psychedelic experience. Chronic 5-HT2B agonism at high doses raises theoretical cardiovascular concerns, though this is not a documented issue at therapeutic psilocybin doses.

Full Explanation

The 5-HT2B receptor is a serotonin receptor subtype expressed in cardiovascular tissue, the gastrointestinal system, and the trigeminal system. Distinct from the 5-HT2A receptor that mediates psilocybin's psychedelic and antidepressant effects. 5-HT2B and 5-HT2C agonism may mediate psilocybin's preventive effects on cluster headaches and migraines at sub-psychedelic doses — explaining why therapeutic headache benefits occur independently of the intensity of the psychedelic experience. Chronic 5-HT2B agonism at high doses raises theoretical cardiovascular concerns, though this is not a documented issue at therapeutic psilocybin doses.

See: Cluster Headaches (/conditions/cluster-headaches).

Why It Matters

Understanding 5-HT2B helps explain why psilocybin can relieve cluster headaches at sub-psychedelic doses and why headache benefits do not depend on having a strong psychedelic experience.

Related Terms

5-HT2A receptor
Back to Glossary

Explore More Terms

5-HT2A receptor

The primary serotonin receptor in the brain that psilocin binds to, producing psychedelic effects.

BOL-148

A non-hallucinogenic analogue of LSD (2-bromo-lysergic acid diethylamide) with no significant 5-HT2A receptor activity. Studied as a preventive treatment for cluster headache, BOL-148 produces headache-frequency reductions without psychedelic effects — providing strong evidence that psilocybin's therapeutic action in headache disorders is neurological rather than psychological. (Karst et al., Cephalalgia, 2010)

Cluster-busting

A patient community term for using sub-psychedelic doses of psilocybin or LSD to abort or prevent cluster headache attacks. The practice was documented and shared online since the 1990s, formalised by the Clusterbusters patient advocacy organisation, and subsequently verified in a 2015 survey (Schindler et al., Journal of Psychoactive Drugs) showing 50–80% of cluster headache patients who tried psychedelics reported benefit — often at sub-hallucinogenic doses. This patient-led observation drove Yale's formal clinical investigation.

Afterglow

The period of heightened mood, openness, and mental flexibility that commonly follows a full-dose psilocybin session — typically lasting 24 hours to several weeks. During the afterglow, neuroplasticity is elevated, default mode network activity is altered, and emotional and cognitive patterns are unusually open to change. Considered the critical integration window: therapeutic insights translate into lasting behavior change most effectively during this period. (Majić et al., 2015)

Spores

Reproductive cells produced by mushrooms, used to start new cultures and legal to possess in most US states.

Set and Setting

The combination of mindset (set) and environment (setting) that shapes a psychedelic experience.

PsyBear logo — psilocybin education and harm reductionPsyBear

The most comprehensive information and discovery destination for magic mushrooms. Education, safety, and community first.

Magic Mushrooms

  • About
  • Strains
  • Species
  • Forms
  • Effects

Discover

  • Dosage Calculator
  • Churches
  • Retreats
  • Legal Status
  • Grow Guides
  • Compare Strains
  • Therapy Comparisons

Conditions

  • Depression
  • Anxiety
  • PTSD
  • Addiction
  • OCD

Guides

  • Safe Trip
  • Trip Sitter
  • Ceremony Etiquette
  • vs SSRIs
  • Microdosing

Resources

  • Blog
  • Research
  • Glossary
  • Events

Company

  • About
  • Contact
  • Membership
  • Privacy
  • Terms

© 2026 PsyBear · psybear.co

Made with ♥ in Northern California

Disclaimer: PsyBear provides educational information only. We do not sell, distribute, or encourage the illegal use of controlled substances. Psilocybin remains Schedule I federally. Oregon and Colorado have state-licensed supervised psilocybin programs as of 2026.