Tadalafil is a medication used for several conditions:

• Erectile Dysfunction (ED): It helps men who have trouble getting or keeping an erection by increasing blood flow to the penis during sexual stimulation.
• Benign Prostatic Hyperplasia (BPH): It treats symptoms related to an enlarged prostate, such as difficulty urinating, weak stream, and urgency, by relaxing the muscles in the prostate and bladder.
• Pulmonary Arterial Hypertension (PAH): It relaxes blood vessels in the lungs to lower blood pressure and improve exercise ability.

Tadalafil works by blocking an enzyme called phosphodiesterase 5 (PDE5), which leads to muscle relaxation and increased blood flow in the targeted areas. It does not cure ED or increase sexual desire on its own and requires sexual stimulation to work. It is available by prescription and sold under brand names like Cialis (for ED and BPH) and Adcirca (for PAH). In summary, tadalafil is mainly used for erectile dysfunction, enlarged prostate symptoms, and pulmonary hypertension. It helps improve blood flow and relaxes muscles in these specific conditions.