Avodart is used to treat symptoms of an enlarged prostate (benign prostatic hyperplasia - BPH). Avodart works by reducing the size of an enlarged prostate gland. This helps relieve symptoms of the disease such as difficulty urinating, weak urine flow, and the need to urinate more often or more urgently including in the middle of the night. Avodart may also reduce the need for surgery to treat an enlarged prostate.