Tastylia, known as Tadalafil, works by inhibiting the enzyme phosphodiesterase type 5 (PDE5). This enzyme is responsible for breaking down a compound called cyclic guanosine monophosphate (cGMP), which is involved in smooth muscle relaxation in the penis. By inhibiting PDE5, Tastylia 20 helps to increase the levels of cGMP, resulting in improved blood flow to the penis and ultimately, a better erection.