What vaigra do?

Viagra, whose active ingredient is sildenafil, is a medication primarily used to treat erectile dysfunction by increasing blood flow to the penis, helping achieve and maintain an erection when combined with sexual stimulation. It works by inhibiting an enzyme called phosphodiesterase type 5 (PDE5), which allows for increased levels of a substance called cyclic GMP that relaxes blood vessels. The effects typically last for about four to six hours, making it effective for spontaneous sexual activity. It's important to use Viagra under a doctor's guidance due to potential side effects and interactions with other medications.