This condition may require prompt medical treatment to prevent serious and permanent damage to your penis. Children 1 year of age and older weighing 20 kg or less—10 mg 3 times a day. Click here for an email preview. Erectile dysfunction medications require a prescription from a licensed provider. Some services offer a subscription option where they’ll send your medications every month at a discount. · The effects may be increased because of slower removal of the medicine from the body. 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. Find information on sildenafil and cost, how generic and brand-name prices compare, what financial assistance is available, and more. Viagra (sildenafil) and cost. Viagra (sildenafil) is a brand-name oral tablet prescribed for erectile dysfunction. The cost of the drug with and without insurance can depend on several factors.