Tadalafil is a medicine in a group called PDE5 inhibitors. It relaxes the smooth muscle in blood vessel walls, which helps blood flow to the penis when you are sexually aroused. It does not cause an erection on its own, and it does not increase sexual desire.
In Malaysia, tadalafil is a prescription medicine. It is used for erectile dysfunction, and the 5mg daily dose is also used for urinary symptoms caused by an enlarged prostate (benign prostatic hyperplasia). It is sold under the originator brand Cialis and as generic versions such as Tadigra.
Tadalafil stays in the body longer than some other medicines in its group, which is why it can be taken once a day at a low dose or as a single higher dose when needed. How well it works varies from person to person.