3C-P

Heart disease, Hypertension, Arrhythmia, Structural heart disease

Pre-existing cardiac conditions, hypertension, arrhythmias, and structural heart disease represent absolute contraindications. User reports at 40–43 mg oral document tachycardia, chest pressure, and peripheral vasoconstriction, exacerbated by physical exertion. The 10–16 hour duration imposes sustained sympathetic activation.

Epilepsy, Seizure history

Pre-existing epilepsy or seizure history constitutes a relative contraindication. Phenethylamine psychedelics have been associated with seizure threshold reduction, and seizures are documented in the 2C-series sympathomimetic toxidrome (Dean et al. 2013).

Schizophrenia, Schizoaffective disorder, Psychotic episodes

Personal or family history of psychotic spectrum disorders constitutes a relative contraindication. 5-HT2A agonists disrupt default mode network integrity and thalamocortical filtering, potentially precipitating psychotic episodes in predisposed individuals.

Bipolar I, Bipolar II

Bipolar disorder represents a relative contraindication due to the risk of manic episode precipitation. The extended 10–16 hour duration of 3C-P amplifies this risk relative to shorter-acting psychedelics.

Liver disease

Hepatic impairment represents a relative contraindication. With no metabolic pathway data available for 3C-P, impaired liver function could produce unpredictable increases in exposure and duration, compounding the cardiovascular and psychological risks of the 10–16 hour experience.

Kidney disease

Renal impairment represents a relative contraindication. Without urinary recovery or renal clearance data, the contribution of renal elimination to 3C-P's total clearance is unknown, and impaired kidney function could prolong exposure.

Pregnancy, Breastfeeding

Use during pregnancy or lactation is absolutely contraindicated. No reproductive toxicity data exist for 3C-P, and the compound's sympathomimetic and serotonergic properties pose unquantified risks to fetal and neonatal development.

MAOIs

Monoamine oxidase inhibitors are absolutely contraindicated due to dual risk: serotonin syndrome from combined serotonergic potentiation, and blocked metabolism of the amphetamine scaffold leading to unpredictable exposure increases.

SSRIs, SNRIs

Concurrent use of SSRIs or SNRIs is contraindicated due to serotonin syndrome risk and unpredictable interaction effects. The combination may both attenuate psychedelic effects and increase serotonergic toxicity risk.

Tramadol

Tramadol is absolutely contraindicated. Its SERT inhibition combined with 3C-P's 5-HT2A agonism creates conditions for serotonin syndrome — agitation, hyperthermia, tachycardia, clonus, and potentially fatal muscle rigidity.