Contraindications

Contraindications are conditions, medications, or circumstances that make the use of a substance inadvisable - either because the risk of harm is substantially elevated, because an interaction with another compound may be dangerous, or because the psychological or physiological demands of the experience exceed what the person can safely manage at a given time.

For classical psychedelics, the most significant contraindications involve psychiatric history. A personal or first-degree family history of psychosis, schizophrenia, or bipolar disorder with psychotic features represents a genuine elevated risk. Psychedelic experiences suppress the brain's ordinary reality-testing and self-monitoring systems; in individuals whose capacity for reality-testing is already impaired or who have a biological predisposition toward its impairment, this suppression can trigger extended psychotic episodes. Current research protocols screen carefully for these conditions, and this screening is one of the primary reasons adverse events in clinical trials have been rare.

Active suicidal ideation is a contraindication in research settings, though the picture here is complex: psilocybin and ketamine have both shown promise in reducing suicidal ideation. The distinction is between chronic, passive suicidal ideation in a person who is stable enough to engage in therapeutic work, and acute active intent where a psychedelic session would create additional risk.

Cardiovascular conditions - particularly serious cardiac arrhythmias - may be relevant for some psychedelics that produce physiological activation. Blood pressure and heart rate typically increase modestly during a psychedelic experience; for most people this is within safe limits, but for people with certain cardiac vulnerabilities it warrants medical evaluation.

Medication interactions require case-by-case assessment. SSRIs and SNRIs reduce the effects of classical psychedelics (serotonin reuptake inhibition reduces the availability of the serotonin system that psychedelics act on) and may in rare cases contribute to serotonin syndrome. Lithium has been associated with seizure risk in combination with some psychedelics. MAOIs interact dangerously with many compounds. Any prescription medication should be checked against the specific substance being considered.

Current life circumstances also matter. Active trauma exposure, a period of major life crisis, or the absence of any post-experience support may not constitute contraindications in the strict sense but are worth examining as preparation questions.