The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive. Especially tell your healthcare provider if you take any of the following: medicines called nitrates medicines called guanylate cyclase stimulators such as Adempas riociguat medicines called alpha-blockers, such as Hytrin terazosin HCl , Flomax tamsulosin HCl , Cardura doxazosin mesylate , Minipress prazosin HCl , Uroxatral alfuzosin HCl , Jalyn dutasteride and tamsulosin HCl , or Rapaflo silodosin. How should this medicine be used? Children—Use is not recommended. Children 1 year of age and older weighing 20 kg or less—10 mg 3 times a day. For treatment of pulmonary arterial hypertension: For oral dosage forms suspension or tablets : Adults—20 milligrams mg 3 times a day.Drug Images What is Viagra? Viagra is a brand-name prescription drug that’s approved to treat erectile dysfunction (ED). With ED, you’re unable to have or maintain an erection. Viagra is. Sildenafil (Viagra) is used to treat erectile dysfunction (impotence; inability to get or keep an erection) in men. Sildenafil (Liqrev, Revatio) is used to improve the ability to exercise in adults (Liqrev, Revatio) and children 1 year of age and older (Revatio) with pulmonary arterial hypertension (PAH; high blood pressure in the vessels carrying blood to the . How much does generic Viagra cost? Generic Viagra usually costs anywhere from about $2–$