Dapoxetine hydrochloride is a selective serotonin reuptake inhibitor (SSRI) used as an active pharmaceutical ingredient (API) for the treatment of premature ejaculation in men. It works by increasing serotonin levels in the brain, helping to delay ejaculation and improve control during sexual activity. Typically taken on-demand, it has a rapid onset of action and a short half-life. Common side effects may include nausea, dizziness, and headache, making it important to use under medical supervision.