Megalis-10 Tablet is used to treat erectile dysfunction (impotence) and benign prostatic hyperplasia (BPH). Sometimes, it is also used to treat pulmonary arterial hypertension (high blood pressure in the lungs). It contains Tadalafil, which works by relaxing the blood vessels in the penis; this allows the blood to flow into the penis when the person is sexually excited. Thereby, it helps to treat erectile dysfunction. It relaxes the bladder and prostate muscles, thereby reducing enlarged prostate symptoms such as difficulty in urination and urgent need to urinate. It is used to treat pulmonary hypertension (high blood pressure in the lungs) by relaxing the blood vessels in the chest. Thereby increasing the blood supply to the lungs and decreasing the workload of the heart. In some cases, you may experience common side effects such as headache, back pain, muscle pain, pain in the legs and arms, nasal congestion, indigestion, and facial flushing.