Tadalis SX (Tadalafil) 20mg is a treatment for erectile dysfunction in men. During sexual stimulation, Tadalis (Tadalafil) enables a man’s penis to fill with enough blood to cause an erection. It does this by blocking an enzyme called phosphodiesterase-5, or PDE-5. This helps the smooth muscles in the penis relax and widen, which allows for more blood to enter. After sex is over, the erection goes away. You will not get an erection by just taking Tadalis (Tadalafil). Sexual stimulation is required for Tadalis (Tadalafil) to be effective. Your doctor or health care professional is always your best source of information when evaluating treatments for erection problems.