Severe liver disease. Oral medicines for ED usually work well and cause few side effects. Oral medicine for ED also might not be safe or work well if you have: Very low blood pressure, called hypotension, or uncontrolled high blood pressure, called hypertension. These are commonly prescribed for an enlarged prostate or male pattern baldness. Do not take more or less of it or take it more often than prescribed by your doctor. This will increase the supply of blood to the lungs and reduce the workload of the heart. Slowly pull back the plunger until the required dose. · Sildenafil under the name Viagra is used to treat erectile dysfunction (impotence) in men. Another brand of sildenafil is Revatio, which is used to treat pulmonary arterial hypertension and improve exercise capacity in men and women. Do not take Viagra while also taking Revatio. Warnings. Oral medications are a successful erectile dysfunction treatment for many men. They include: Sildenafil (Viagra) Tadalafil (Adcirca, Cialis) Vardenafil (Levitra, Staxyn) Avanafil (Stendra) All four medications enhance the effects of nitric oxide — a natural chemical your body produces that relaxes muscles in the penis. It’s a prescription drug that’s used in adult males* with ED. With ED, you have trouble getting or keeping an erection. Viagra treats ED by increasing the amount of blood flow to your penis.