Sildenafil usually should not be taken more than once every 24 hours. No dose adjustment is required for mild to moderate hepatic impairment. Your doctor will tell you not to take sildenafil if you are taking street drugs containing nitrates. Without physical action to the penis, such as that occurring during sexual intercourse, sildenafil will not work to cause an erection. Rarely reported side effects include: an erection that will not go away priapism. Follow the manufacturer’s directions to use and clean the oral syringe.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 . Bookshelf ID: NBK PMID: Sildenafil is a medication used in the management and treatment of erectile dysfunction and pulmonary arterial hypertension. It is in the phosphodiesterase-5 inhibitor (PDE5-I) class of medications. This activity describes the indications, actions, adverse effects, and contraindications of . AdRead Customer Reviews & Find Best Sellers. Free, Easy Returns On Millions Of Items. Get Deals and Low Prices On sildenafil mg On Amazon1M+ visitors in the past month.