Used primarily to treat erectile dysfunction (ED), helping men achieve and maintain an erection during sexual activity. Also prescribed for pulmonary arterial hypertension (PAH) to improve exercise capacity by relaxing blood vessels in the lungs. Another approved use is for benign prostatic hyperplasia (BPH), relieving symptoms like difficulty urinating by relaxing smooth muscles in the prostate and bladder. Its long duration of action allows for once-daily dosing in chronic conditions.