If you are a Mayo Clinic patient, this could include protected health information. This is a type of high blood pressure that occurs between the heart and the lungs. If we combine this information with your protected health information, we will treat all of that information as protected health information and will only use or disclose that information as set forth in our notice of privacy practices. By controlling the enzyme, sildenafil helps to maintain an erection after the penis is stroked. You’ll soon start receiving the latest Mayo Clinic health information you requested in your inbox. These are commonly prescribed for an enlarged prostate or male pattern baldness.Sildenafil (Viagra). This medicine works best when you take it on an empty stomach an hour before sex. The body takes longer to absorb it after a high-fat meal or alcohol. Its effects . In most males,* Viagra works within 1 hour after it’s taken. It’s possible that Viagra can begin working within 30 minutes of being taken. But other times, it may take up to 4 . Revatio Viagra Descriptions Sildenafil is used to treat men who have erectile dysfunction (also called sexual impotence). Sildenafil belongs to a group of medicines called .