Table 1.

Medications associated with priapism

Class	Drugs	Potential mechanism
Antihistamine	Hydroxyzine	Used as an antianxiety drug because of its effect on serotonin. May cause priapism due to interference with α-adrenergic property.
Anesthetic	Propofol	Potential mechanisms include vasodilatation, inhibition of sympathetic response, and enhancing smooth muscle relaxation effect of nitric oxide.
Antihypertensives	Hydralazine, guanethidine	Likely through vasodilation.
Anticonvulsants	Sodium valproate, pregabalin	Possibly induces priapism through increasing parasympathetic tone or alteration of phosphodiesterase expression.
α-Adrenergic blockers	Tamsulosin, prazosin, etc	Blocking α-adrenergic receptors will enhance the parasympathetic effect on penile smooth muscles.
Anticoagulants	Warfarin, heparin	Warfarin can cause paradoxical thrombosis, especially in individuals with protein C deficiency. Heparin may cause priapism through activation of platelets by antibodies, leading to thrombosis within penile blood vessels.
Sex hormones	Testosterone, gonadotrophin-releasing hormone	Upregulation of nitric oxide synthase.
Antipsychotics	Chlorpromazine, haloperidol, olanzapine, zuclopenthixol, lithium, etc	Proposed to cause priapism via α-adrenergic inhibition.
Antidepressants	Citalopram, fluoxetine, trazodone	Causes priapism via interference with sympathetic control.
Vasodilators	Papaverine, drotaverine, prostaglandin E, alprostadil, phentolamine	Papaverine is a nonselective inhibitor of phosphodiesterase.
Medications for attention-deficit disorders	Methylphenidate, atomoxetine	Acts via blocking norepinephrine and dopamine reuptake channel.
Recreational drugs	Alcohol, marijuana, cocaine	Cannabis may cause priapism by blocking sympathetic response or activating platelets, leading to thrombosis. Cocaine may cause depletion of norepinephrine from nerve terminals.

(Reproduced from Idris et al.,²³ with a slight modification, with the permission of the Blood Advances.)