You can use prescription medicine taken by mouth (oral medicine) for erectile dysfunction (ED). They often work well. But like all medicines, they can have side effects. Also, you can't use them if you have certain health problems or take certain other medicines. Talk with your doctor about oral ED medicine. Ask if it's right for you.

Your doctor may advise 1 of 4 different prescription oral ED medicines. Each one increases blood flow to the penis. When the penis is stimulated, an erection results. The medicines are:

• Sildenafil citrate
• Tadalafil
• Vardenafil
• Avanafil

There are some things ED medicines can't do.

• They don't cure the cause of your ED. Without the medicine, you'll still have trouble getting an erection.
• They can't produce an erection without sexual stimulation.
• They won't increase sexual desire. They also won't solve any other sexual issues. Psychological, emotional, or relationship issues won't be fixed.

• Don't combine ED medicines with other treatments unless your doctor tells you to.
• Don't take ED medicines more often or in larger doses than prescribed.
• Tell your doctor about your health history. Mention all medicines you take. This includes over-the-counter and prescription medicines, vitamins, herbs, and other supplements.
• Ask your doctor if you can drink alcohol while taking ED medicine.
• Check with your pharmacist before using any new over-the-counter medicines to make sure that they're safe to use with your ED medicine.

• Headache
• Facial flushing
• Runny or stuffy nose
• Indigestion
• Distorted color vision for a short time
• Dizziness
• Sudden vision or hearing loss (rare)
• Erection that lasts 4 hours or longer

• Taking ED medicines with medicines that contain nitrates can cause your blood pressure to drop to a dangerous level. Nitrates include nitroglycerin (a medicine for angina or chest pain). They are also in “poppers,” an inhaled recreational drug. Don't take ED medicines if you take medicines containing nitrates. If you're not sure if you're taking nitrates, ask your doctor or pharmacist.
• Medicines called alpha-blockers can interact with ED medicines. They can cause a sudden drop in blood pressure. Alpha-blockers are a common treatment for prostate problems. They're also used to treat high blood pressure. Be sure your doctor knows if you take these medicines.
• If you've had a heart attack or have heart disease and you haven't had sex for a while, having sex again can put extra strain on your heart. Talk with your doctor about whether your heart is healthy enough for sex.
• It's rare, but some men taking ED medicines have had sudden vision loss. This may be more likely if you have other health problems, such as high blood pressure and diabetes. Ask your doctor if you're at risk for this type of vision loss.
• In rare cases, an erection may last too long. This can badly damage the blood vessels in your penis. If an erection lasts longer than 4 hours, go to the emergency room right away.