Trazodone (Desyrel) is associated with which rare adverse effect?

• A. Hyponatremia
• B. Serotonin syndrome
• C. Priapism
• D. Agranulocytosis

Answer: (C)

Trazodone’s rare but important adverse effect is priapism—a prolonged, often painful erection not related to sexual stimulation. This happens because trazodone can alter penile blood flow and smooth muscle tone through its actions on serotonin pathways and alpha-1 adrenergic receptors, which can impair normal detumescence. Because prolonged erections can cause ischemia and potential long-term erectile dysfunction, it’s a medical emergency: seek urgent care if an erection lasts longer than about four hours, and consider stopping trazodone until evaluated.

Hyponatremia can occur with some antidepressants, particularly SSRIs, due to SIADH, but it’s not the hallmark rare adverse effect of trazodone. Serotonin syndrome is a risk when serotonergic drugs are combined, but it’s not a unique or common adverse effect of trazodone alone. Agranulocytosis is not associated with trazodone.