How Does Viagra Work?Viagra helps increase blood flow to the penis when sexually aroused, allowing men to achieve and maintain an erection sufficient for sexual activity. The active ingredient in Viagra is sildenafil, a PDE5 inhibitor. It works by blocking the enzyme PDE5, which normally regulates blood flow in the penis. By inhibiting this enzyme, sildenafil amplifies the natural arousal process, enhancing blood flow to the penis during sexual stimulation. While sildenafil aids in achieving an erection, it requires natural sexual arousal as a trigger. Other PDE5 inhibitors like tadalafil, vardenafil, and avanafil also support sexual function when erections are difficult to maintain. How to Take ViagraThe typical starting dose for Viagra is one 50mg tablet for men who have not used it before. Men over 65 years old may begin with a lower dose of 25mg. Viagra takes effect within 30 to 60 minutes and lasts for up to 4 hours. If the 50mg dose works well, future doses may be reduced to 25mg. If the 50mg dose is not effective or doesn't last for 4 hours, the dose can be increased to 100mg. Do not take more than one dose per day or exceed the 100mg limit, as higher doses do not improve results and can increase the risk of side effects. Viagra requires sexual arousal to work effectively. It is most effective when taken an hour or two before sexual activity. Without sexual arousal, the medication will have no effect and will wear off after about 4 hours. Avoid large meals, high-fat foods, excessive alcohol, and grapefruit, as these can reduce the effectiveness of Viagra.