4-HO-DET

Pre-existing cardiovascular conditions including uncontrolled hypertension, coronary artery disease, heart failure, or arrhythmias. The autonomic activation associated with 5-HT2A agonism produces transient increases in heart rate and blood pressure that are generally benign in healthy individuals but may be clinically significant in cardiovascular-compromised patients.

Personal or family history of schizophrenia, schizoaffective disorder, or other psychotic disorders. 5-HT2A agonist psychedelics can trigger acute psychotic episodes in vulnerable individuals. This is a class-level contraindication supported by extensive clinical psychedelic literature.

Bipolar disorder type I or II. Psychedelic experiences may destabilize mood cycling and precipitate manic or mixed episodes. Combined lithium use (common in bipolar management) further increases risk via seizure threshold reduction.

No safety data exist for 4-HO-DET use during pregnancy or breastfeeding. Contraindicated as a precautionary measure given the absence of reproductive toxicity data and the known role of serotonin in fetal development.

Concurrent use of monoamine oxidase inhibitors (irreversible or reversible) is contraindicated due to serotonin syndrome risk. MAOIs potentiate tryptamine effects by blocking metabolic degradation and increasing synaptic serotonin concentrations.

Concurrent tramadol use is contraindicated due to serotonin syndrome risk. Tramadol's SERT inhibition (demonstrated in human SERT-transfected HEK293 cells) produces additive serotonergic load when combined with 5-HT2A agonists. The FDA has linked tramadol to serotonin toxicity risk.

Concurrent lithium use is contraindicated. Case reports document increased seizure risk and unpredictable behavioral disturbances when lithium is combined with classical psychedelics.