This medicine works best when you take it on an empty stomach an hour before sex. Often, these are prescribed for chest pain called angina. As with sildenafil, a high-fat meal or alcohol keep the body from absorbing it as quickly. This will increase the supply of blood to the lungs and reduce the workload of the heart. Medicines that you take by mouth are called oral medicines. Store mixed oral liquid in the refrigerator.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 . VIAGRA contains sildenafil, which is the same medicine found in another drug called REVATIO. REVATIO is used to treat a rare disease called pulmonary arterial . Sildenafil is used to treat male sexual function problems (impotence or erectile dysfunction-ED). In combination with sexual stimulation, sildenafil works by increasing .