Children 1 year of age and older weighing 20 kg or less—10 mg 3 times a day. If it is not treated right away, priapism can permanently damage your penis sudden vision loss in one or both eyes. Precautions It is important that you tell all of your doctors that you take sildenafil. These medicines all work well for ED. Take sildenafil as needed before sexual activity. As with sildenafil, a high-fat meal or alcohol keep the body from absorbing it as quickly.Less than 2% of men with erection problems reported their symptoms first started before the age of Only 4% reported symptoms of ED starting between 40 and 49 years of age. About 1 in 4 said their ED symptoms started between the ages of 50 to Two in five men reported their symptoms started between age 60 and VIAGRA can cause serious side effects. Rarely reported side effects include: an erection that will not go away (priapism). If you have an erection that lasts more than 4 hours, get medical help right away. 1 day ago · How we vet brands and products. If you’re interested in buying Viagra online, five of the best options available are Hims, Roman, Lemonaid, Optum Store, and REX MD. Read on for full details on.