Vidalista 40 mg is a medication used to treat erectile dysfunction (ED) in men. Its active ingredient is tadalafil, a PDE5 inhibitor that helps increase blood flow to the penis, enabling an erection when sexually stimulated. Tadalafil works by inhibiting the enzyme PDE5, which normally breaks down cGMP, a compound that relaxes blood vessels in the penis. This leads to enhanced blood flow, resulting in a firmer and sustained erection.