To provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and site usage information with other information we have about you. If it is not treated right away, priapism can permanently damage your penis sudden vision loss in one or both eyes. Leukemia blood related cancer or Multiple myeloma blood related cancer or Sickle-cell anemia blood disorder —Sildenafil should be used with caution in these patients as problems with prolonged erection of the penis may occur. Children 1 year of age and older weighing 45 kilograms kg or more—20 mg 3 times a day. You may take this medicine with or without food. If you experience a prolonged or painful erection for 4 hours or more, contact your doctor immediately. · For treatment of erectile dysfunction: For oral dosage form (tablets): Adults up to 65 years of age—50 milligrams (mg) as a single dose no more than once a . Viagra: This drug is used to treat ED. With ED, you’re unable to get or maintain an erection. Revatio: This drug is used to treat PAH. With PAH, the blood . VIAGRA is available by prescription only in 25 mg, 50 mg, and mg tablets. Patients should always ask their doctors for medical advice about adverse events. You are .