When choosing one, tell your doctor or other health care professional what your preferences are, such as cost, ease of use, how long the drug’s effects last and side effects. Recent heart or blood vessel problems. They include dutasteride Avodart, Jalyn and finasteride Propecia, Proscar. When oral medications might not be safe Check with your health care team before you take any medicine for erectile dysfunction. You’ll soon start receiving the latest Mayo Clinic health information you requested in your inbox.Viagra takes around 30 minutes to become effective and lasts about 4 hours. Cialis lasts much longer — up to 36 hours in some cases. Stendra can start doing its thing in as little .  · Viagra; Descriptions. Sildenafil is used to treat men who have erectile dysfunction (also called sexual impotence). Sildenafil belongs to a group of medicines . Last updated: June 14, If you’re looking for a less costly Viagra, you might want to ask your doctor about sildenafil. It’s the active ingredient in both branded Viagra and the drug.