4-HO-MET

Substance-specific preclinical data (Yoon et al. 2020) demonstrate hERG inhibition and QT prolongation. Individuals with congenital or acquired long QT syndrome face additive arrhythmia risk. This is the best-evidenced contraindication for 4-HO-MET, supported by substance-specific experimental data rather than class-level inference alone.

Concurrent use of QT-prolonging medications creates additive arrhythmia risk given 4-HO-MET's demonstrated hERG channel inhibition. Relevant drug classes include Class IA/III antiarrhythmics, macrolide antibiotics, fluoroquinolones, and certain antipsychotics.

Personal or family history of psychotic disorders (schizophrenia, schizoaffective disorder, psychotic episodes) constitutes an absolute contraindication. One published case of 4-HO-MET-induced acute psychosis in an adolescent first-time user supports this classification. The risk is consistent with the class-level psychotomimetic potential of serotonergic psychedelics.

Bipolar disorder, particularly with psychotic features or lithium co-medication. Simonsson et al. 2023 found lithium co-use significantly associated with degree of difficulty and risk of harm during classic psychedelic experiences. The dual risk — psychotomimetic potential and lithium interaction — supports relative contraindication.

Severe hepatic impairment could significantly alter 4-HO-MET pharmacokinetics given the compound's extensive hepatic metabolism (12 phase I metabolites identified by Bruni et al. 2018). Reduced clearance may increase exposure and serotonin toxicity risk. Class-level inference — no substance-specific hepatic impairment data.

No animal or human reproductive toxicity data exist. Absolute contraindication based on absence of safety data and theoretical risk of serotonergic disruption to fetal development. Standard precautionary classification for uncharacterized psychoactive substances.

The only published psychiatric adverse event for 4-HO-MET occurred in an adolescent first-time user (Täljemark 2012). The developing adolescent brain may be more susceptible to serotonergic disruption and psychotomimetic effects. Relative contraindication supported by the single case report and class-level neurodevelopmental concerns.