Tadarise 20 contains a common drug ingredient called tadalafil. These tablets belong to a class of drugs known as PDE-5 inhibitors of tadalafil. This drug is a class of PDE5 inhibitor tablets used to treat erectile dysfunction (ED) or impotence in men. This drug works by increasing the amount of blood in the penis to make erection easier. This medicine should be taken with a glass of water. The effectiveness of this pill lasts up to 36 hours during sexual intercourse.