2C-H

Active 2C-series compounds have been associated with hypertension, tachycardia, and sympathomimetic cardiovascular effects. While 2C-H's very weak 5-HT₂A affinity (Ki 1,600 nM) makes clinically significant cardiovascular effects unlikely at oral doses, the contraindication is retained as a class-level precaution.

Seizures have been documented in acute toxicity presentations involving active 2C-series compounds such as 2C-E, 2C-I, and 2C-B. Whether 2C-H can lower seizure threshold at any achievable dose is unknown, but the contraindication is retained as a class-level precaution for individuals with existing seizure disorders.

Psychotic spectrum disorders, Severe anxiety disorders, Bipolar disorder

Standard contraindication for the 2C phenethylamine class and serotonergic psychedelics broadly. Active 2C compounds can precipitate psychotic episodes, severe anxiety, and destabilize mood disorders. 2C-H's very weak receptor activity makes these effects unlikely at oral doses, but the contraindication is retained as a class-level precaution.

2C-H inhibits MAO-B with an IC₅₀ of 1.7 µM — the most potent MAO-B inhibition in the 2C series. Concurrent use with any monoamine oxidase inhibitor (pharmaceutical MAOIs, ayahuasca, Syrian rue) creates risk of additive MAO inhibition with dangerous monoamine accumulation. Additionally, MAOIs could paradoxically convert 2C-H from an orally inactive compound to an orally active one by preventing the first-pass MAO-B degradation that normally renders it inactive.

Tramadol exerts serotonergic effects through serotonin reuptake inhibition and stimulation of serotonin release. 2C-H compounds this risk through two mechanisms: weak 5-HT₂A partial agonism and potent MAO-B inhibition (IC₅₀ 1.7 µM). The MAOI-tramadol combination is specifically identified as a contraindicated pairing in pain management literature due to serotonin syndrome risk.

Individuals with a history of serotonin syndrome may have a lowered threshold for recurrence when exposed to any serotonergic agent. 2C-H provides both weak direct 5-HT₂A agonism and MAO-B inhibition, either of which could contribute to serotonergic load.