Megalis 20 mg is a medication primarily used to treat erectile dysfunction (ED) in men. It contains the active ingredient Tadalafil, a phosphodiesterase type 5 (PDE5) inhibitor, which works by increasing blood flow to the penis to help achieve and maintain an erection. Tadalafil is the key component in Megalis 20 mg. It works by inhibiting the enzyme PDE5, which results in the relaxation of the blood vessels in the penis and increased blood flow during sexual stimulation.