It lasts 4 to 5 hours, or longer if you have mild to moderate ED. If you experience chest pain, dizziness, or nausea during sex, seek immediate medical help. When oral medications might not be safe Check with your health care team before you take any medicine for erectile dysfunction. The four main medicines taken by mouth for erectile dysfunction are: Avanafil Stendra. Medicines that block an enzyme called CYP3A4. Avanafil Stendra. Oral medicines for ED usually work well and cause few side effects.Viagra vs. over-the-counter products. Many over-the-counter (OTC) products may be advertised to help with ED. Examples of these products include: dehydroepiandrosterone . Sildenafil (Viagra, Revatio) is a moderately priced drug used to treat erection problems in test1.ru is also used to treat pulmonary arterial hypertension, a serious heart and lung . Generic Viagra (sildenafil) is available as a , , , and milligram (mg) pill and in liquid form. It’s meant to be taken as needed — about an hour before sex — but .