· 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 .If your dose is different, do not change it unless your doctor tells you to do so. To use the oral liquid: Shake the bottle well for at least 10 seconds before each use. Erectile dysfunction symptoms include persistent: Trouble getting an erection Trouble keeping an erection Reduced sexual desire Men of any age may benefit from the use of Viagra Sildenafil if they experience any of the above symptoms. Different brands may not work the same way. Common physical causes:. Men as young as 18 may experience ED.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 . 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 .Store mixed oral liquid in the refrigerator. You may take this medicine with or without food. Rarely reported side effects include: an erection that will not go away priapism. Your doctor may adjust your dose as needed and tolerated. Adults 65 years of age and older—25 mg as a single dose no more than once a day, 1 hour before sexual intercourse. If your dose is different, do not change it unless your doctor tells you to do so. If you see air bubbles in the syringe, repeat the steps.