How does Viagra work? Viagra, scientifically known as sildenafil, is a drug commonly used to treat erectile dysfunction. The effect of this drug is still very good in most people. The reason is that erectile dysfunction has psychological factors and some are organic. If the psychological factors are predominant, the effect of using Viagra is often poor. The use of Viagra for organic factors can assist in erectile function by releasing nitric oxide, which selectively dilates the blood vessels of the penile corpus cavernosum and allows a fuller blood flow. However, this effect must depend on sexual provocation or arousal, without which the treatment of erectile dysfunction will still not work very well. For Viagra to work best, it should be taken 30 minutes before sexual activity. If there is no way to determine when you want to have sexual activity, you can also take it 1-4 hours before sexual activity and it will still be effective. But these people who use Viagra should be aware that they must look at their medication to see if there is a drug called nitrate, such as isosorbide nitrate, isosorbide mononitrate, because these drugs and Viagra, that is, sildenafil are contraindicated and are not to be combined.