Sildenafil Tablet 20mg is widely recognized as the most popular oral medication for erectile dysfunction (ED). It is part of the phosphodiesterase type 5 (PDE5) inhibitors drug class, which also includes tadalafil (Cialis®), vardenafil (Levitra®), and avanafil (Stendra®). Originally developed as heart medications, PDE5 inhibitors were found to be more effective in treating ED by facilitating the relaxation of muscles and decreasing vascular resistance, thereby increasing blood flow to the penis.