Most patients start with 50 mg. Even if you take Viagra, you still need physical and mental stimulation and desire to have an erection. If your first dose of Viagra doesn't help, call your doctor. Your doctor may want to change your tablet size. Headache is the most common side effect.
Vision changes are the least common.
Talk to your doctor if you have any side effect that bothers you. This handout provides a general overview on this topic and may not apply to everyone. To find out if this handout applies to you and to get more information on this subject, talk to your family doctor. Visit familydoctor.org for information on this and many other health-related topics. Permission is granted to print and photocopy this material for nonprofit educational uses.