Megalis 20 is a medication containing Tadalafil as its active ingredient. Tadalafil is primarily used to treat erectile dysfunction (ED) and symptoms of benign prostatic hyperplasia (BPH). It belongs to a class of drugs called phosphodiesterase type 5 (PDE5) inhibitors, which work by increasing blood flow to the penis during sexual stimulation, thus aiding in achieving and maintaining an erection.