Psilocybin
Drugs of abuse
Drugs of abuse
The psychedelic in «magic mushrooms» (Psilocybe species). The body turns it into psilocin, which activates 5-HT2A receptors much like LSD.
Also called: Psilocybine, Magic mushrooms (Psilocybe cubensis and others)
Quick facts
- Group
- Drugs of abuse
- Target
- Serotonin 5-HT2A receptor (via its active form, psilocin)
- Used for
- No approved medical use · Clinical relevance
- Key effects
- Nausea and vomiting · Mydriasis · Altered perception
- Monitor
- Heart rate · Mental state and safety
No doses: the clinician sets them by the current guideline.
Mechanism of action
The figure shows psilocin, the active form of psilocybin, bound to the human 5-HT2A receptor (crystal structure).
Psilocybin is a prodrug: after it is eaten, the phosphate group is removed and it becomes psilocin. Psilocin activates serotonin 5-HT2A receptors in the cortex, the same target as LSD, which alters perception, emotion and the sense of self. Its effects resemble those of LSD and depend strongly on the person's expectations and surroundings. It is not considered addictive, but the experience can be frightening and lead to dangerous behaviour.
- Psilocybin is eaten in mushrooms, raw or as tea
- It is dephosphorylated to psilocin
- Psilocin activates cortical 5-HT2A receptors
- Altered perception and emotion, like LSD
Indications
- No approved medical use; formulations are under study for depression with psychological support Major depressive disorder →
- Clinical relevance: hallucinogen intoxication and poisoning by misidentified wild mushrooms Hallucinogen and dissociative drug intoxication (LSD, PCP, ketamine) →
Adverse effects
Common
- Nausea and vomiting
- Raised heart rate and blood pressure
- Mydriasis, ataxia and restlessness
- Altered perception, fear, confusion or agitation
Contraindications
- No medical use outside research
- Psychotic illness or vulnerability to it
- Heart disease (raised heart rate and blood pressure)
Key interactions
- Other serotonergic drugs and hallucinogens
- Stronger and less predictable effects
- Stimulants
- More tachycardia, hypertension and anxiety
What is monitored
- Heart rate, blood pressure and temperature
- Mental state and safety
- Signs of other mushroom toxins: late vomiting, liver or kidney injury
Pregnancy and breastfeeding
There are no safety data for use in pregnancy.
Nursing care
- Provide calm reassurance in a quiet, safe space
- Ask for a sample or photo of the mushroom and the time eaten
- Benzodiazepines are used for severe agitation
- Watch for symptoms that start late, which suggest a different, dangerous mushroom
Pharmacokinetics
- Absorption
- Taken by mouth in fresh or dried mushrooms, mixed with food or brewed as tea
- Metabolism
- Converted to the active psilocin after ingestion
Test yourself
Think of the answer, then tap the question to see it.
What is the active form of psilocybin?
Psilocin, formed when the phosphate group is removed after ingestion.
Which receptor does psilocin share with LSD?
The serotonin 5-HT2A receptor.
Why is the mushroom's identity important in a patient who ate wild mushrooms?
A toxic species may have been mistaken for a psilocybin mushroom; late symptoms suggest a dangerous toxin.
Connections
← Back to the class: Drugs of abuse
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Psilocybin (Magic Mushrooms) (National Institute on Drug Abuse (NIDA), 2026); Guía para el Manejo de Emergencias Toxicológicas (Ministerio de Salud y Protección Social; Organización Panamericana de la Salud, 2017).
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Representative model, for educational purposes only.