Keep from freezing. It increases your libido, and helps you get and maintain an erection for longer. Leading causes of ED are listed below. However, the dose is usually not more than 80 mg 3 times a day. Follow your doctor’s orders or the directions on the label. For treatment of pulmonary arterial hypertension: For oral dosage forms suspension or tablets : Adults—20 milligrams mg 3 times a day. If you have an erection that lasts more than 4 hours, get medical help right away.RESOURCES GETTING STARTED WITH VIAGRA Your doctor has determined that VIAGRA may be right for you. Follow his or her instructions carefully to help you get the .  · Adults 65 years of age and older—25 mg as a single dose no more than once a day, 1 hour before sexual intercourse. Alternatively, the medicine may be taken 30 . Drug Images What is Viagra? If you have erectile dysfunction (ED), your doctor may recommend that you take Viagra. It’s a prescription drug that’s used in adult .