Some examples of nitrates are nitroglycerin Nitro-Dur, Nitrostat, others , isosorbide mononitrate Monoket and isosorbide dinitrate Bidil. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine. When a man is sexually stimulated, his body’s normal response is to increase blood flow to his penis to produce an erection. To use the oral liquid: Shake the bottle well for at least 10 seconds before each use. Shake the liquid well for 10 seconds before each use to mix the medication evenly. They’re often the first line of treatment for trouble getting or keeping an erection, called erectile dysfunction ED. If you become pregnant while taking sildenafil, call your doctor.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 penis.  · Proper Use. Drug information provided by: Merative, Micromedex ®. Use sildenafil exactly as directed by your doctor. Do not use more of it and do not use it more often than your doctor ordered. If too much is used, the chance of side effects is increased. This medicine comes with a patient information leaflet.  · Description and Brand Names. Drug information provided by: Merative, Micromedex ®. US Brand Name. Revatio. Viagra. Descriptions. 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.