If you are taking sildenafil for PAH, take the missed dose as soon as you remember it. But, you should still see your doctor to discuss other health issues. The following nonprescription or herbal products may interact with sildenafil: cimetidine Tagamet HB , St. Most adults and children aged 1 year and over can take sildenafil for pulmonary hypertension. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.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 .  · Viagra tablets may be taken with or without food. Keep in mind that meals high in fat may cause Viagra to take longer than usual to start working. Viagra is a prescription drug used to treat. Sildenafil (Viagra, Revatio) is a moderately priced drug used to treat erection problems in is also used to treat pulmonary arterial hypertension, a serious heart and lung drug is more popular than comparable drugs. It is available in generic and brand versions. Generic sildenafil is covered by most Medicare and insurance plans, but .