Tadalafil 10 mg Tablets is a phosphodiesterase (PDE-5) inhibitor. It works in erectile dysfunction by increasing blood flow to the penis by relaxing the muscles in penile blood vessels. Tadalafil 10 mg Tablets also relaxes or widens the blood vessels inside the lungs. When the blood vessels relax and widen, it’s easier for the heart to pump blood through the lungs, which reduces blood pressure in the lungs.