Malegra 25 mg is a medication that contains the active ingredient Sildenafil citrate. It is primarily used to treat erectile dysfunction (ED) in men. Sildenafil citrate belongs to a class of drugs called phosphodiesterase type 5 (PDE5) inhibitors. When a man is sexually stimulated, Malegra 25 mg works by increasing blood flow to the penis, allowing for an erection. It achieves this by inhibiting the action of the enzyme phosphodiesterase type 5 (PDE5), which normally breaks down a chemical called cyclic guanosine monophosphate (cGMP). By inhibiting PDE5, cGMP levels increase, promoting smooth muscle relaxation and increased blood flow to the penis.