Before starting, stopping, or changing any medications while taking sildenafil, please get the advice of your doctor or pharmacist. You can take sildenafil with or without food. By controlling the enzyme, sildenafil helps to maintain an erection after the penis is stroked. When a man is sexually stimulated, his body’s normal response is to increase blood flow to his penis to produce an erection. Avanafil Stendra. Some medications should not be taken with sildenafil.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 . Sildenafil is used to treat male sexual function problems (impotence or erectile dysfunction-ED). In combination with sexual stimulation, sildenafil works by increasing blood flow to the.  · Sildenafil is used to treat men who have erectile dysfunction (also called sexual impotence). Sildenafil belongs to a group of medicines called phosphodiesterase 5 (PDE5) inhibitors. These medicines prevent an enzyme called phosphodiesterase type-5 from working too quickly.