Viagra pills work so well that many men don’t bother to question what they actually contain. However, if you’re interested in finding out more about what makes these blue pills work so well, read on. The diamond-shaped tablets are available in 25 mg, 50 mg or 100 mg doses. The main active ingredient is called sildenafil and its role is to control the enzyme restricting blood flow to a man’s penis. The other ingredients include hypromellose, croscarmellose sodium, FD & C Blue #2 aluminum lake, anhydrous dibasic calcium phosphate, microcrystalline cellulose, lactose, magnesium stearate and triacetin. The combination of these compounds increases blood flow the penis. This enables men to enjoy longer and harder erections during sexual intercourse.