Tadalafil is a medication primarily used to treat erectile dysfunction and symptoms of benign prostatic hyperplasia. It works by increasing blood flow to the penis, helping to achieve and maintain an erection when sexually stimulated. Tadalafil is often known by its brand name, Cialis, and can be taken as needed or daily, depending on the prescribed dosage. In addition to its use for erectile dysfunction, tadalafil is also prescribed for pulmonary arterial hypertension, a condition that affects blood flow in the lungs. By relaxing blood vessels, it helps improve exercise capacity and overall quality of life for those with this condition.