These include a heart attack, stroke or a serious heart rhythm disorder in the past six months. The Korean Court system made a ruling against Pfizer in June , allowing for the unhindered domestic production of generic prescription sildenafil. How should this medicine be used? Do not start these medications while taking sildenafil without discussing it with your healthcare provider. If you experience chest pain, dizziness, or nausea during sexual activity, call your doctor immediately and avoid sexual activity until your doctor tells you otherwise. Medicines that you take by mouth are called oral medicines.Viagra; Descriptions. Sildenafil is used to treat men who have erectile dysfunction (also called sexual impotence). Sildenafil belongs to a group of medicines called . Viagra – Uses, Side Effects, and More Generic Name (S): sildenafil Uses Sildenafil is used to treat male sexual function problems (impotence or erectile dysfunction-ED). Sildenafil is in a class of medications called phosphodiesterase (PDE) inhibitors. Sildenafil treats erectile dysfunction by increasing blood flow to the penis during sexual stimulation. .