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Erectile dysfunction: Viagra and other oral medications

Here's how Viagra, Levitra and Cialis compare with each other.

By Mayo Clinic staff

Viagra, Levitra or Cialis are often the first treatment tried for erectile dysfunction. For most men who have trouble keeping an erection firm enough for sex (erectile dysfunction), these medications work well and cause few side effects.

Sildenafil (Viagra), vardenafil (Levitra) and tadalafil (Cialis) are all medications that reverse erectile dysfunction by increasing nitric oxide, a chemical naturally produced by your body. Nitric oxide opens and relaxes blood vessels in the penis, helping you get and keep an erection. These erectile dysfunction medications don't increase your sex drive, though, and cause erections only when you are sexually stimulated.

Viagra, Levitra and Cialis — How they're different

Although they work in similar ways, each of these medications has a slightly different chemical makeup. These minor differences affect the way each medication works, such as how quickly it takes effect and wears off, and the potential side effects. Your doctor will consider these factors when deciding if one of these medications is a good choice for you. Your doctor will also consider any health problems you have and possible interactions with other medications you take.

 ViagraLevitraCialis
How to take it Without food, no more than once a day Without food, no more than once a day With or without food, no more than once a day
When to take it 60 minutes or longer before sex 30 minutes or longer before sex 30 minutes or longer before sex
How long it's effective Up to four hours Up to four hours Up to 36 hours

Side effects

Most men who take Viagra, Levitra and Cialis aren't bothered by side effects. When side effects do occur, they can include:

  • Headache
  • Flushing
  • Indigestion
  • Stuffy or runny nose
  • Back pain and muscle aches (with Levitra)
  • Temporary vision changes, including "blue vision" (with Viagra)

In a small number of cases, men taking Viagra, Levitra or Cialis have reported more serious side effects:

  • Hearing loss or vision loss. Some men have had sudden loss of hearing or loss of vision after taking one of these medications. However, it isn't clear whether vision or hearing loss was directly caused by taking the medication or by a pre-existing condition. If you're taking one of these medications for erectile dysfunction and have sudden loss of hearing or vision, seek medical help right away.
  • An erection that doesn't go away on its own. Called priapism, this rare condition can be painful and requires medical treatment to avoid damage to your penis. If you have an erection that lasts more than four hours, seek medical attention.

When these medications may not be safe

Not all men can safely take erectile dysfunction medications. They can be dangerous if you have certain health problems or you're taking particular medications. Erectile dysfunction medications may not be safe if you have:

  • Heart problems, including heart pain (angina), heart failure, abnormal heart rhythms (arrhythmias) or a recent heart attack
  • High or low blood pressure (hypertension or hypotension) that isn't controlled
  • A history of stroke within the last six months
  • Eye problems such as retinitis pigmentosa, or blood relatives with certain eye problems
  • Sickle cell anemia, leukemia or another health problem that can cause an erection that won't subside (priapism)

Tell your doctor about any medications you're taking. A number of other drugs can also interact with Viagra, Levitra or Cialis. They include:

  • Alpha blockers
  • Antibiotics
  • Anti-seizure medications
  • Blood thinners
  • Anti-arrhythmic heart medications

Never take Viagra, Levitra or Cialis if you take nitrate drugs to treat heart pain (angina). Like Viagra, Levitra and Cialis, nitrates dilate blood vessels. Their combined effects can cause dangerous low blood pressure and loss of consciousness. Medications that contain nitrates include:

  • Nitroglycerin (Nitro-Bid, Minitran, others)
  • Isosorbide (Dilatrate-SR, Isordil, Monoket, others)
  • Illegal drugs such as amyl nitrite or "poppers"
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References
  1. Spark RF. Treatment of male sexual dysfunction. http://www.uptodate.com/home/index.html. Accessed Feb. 9, 2010.
  2. Lue TF, et al. Evaluation and nonsurgical management of erectile dysfunction and premature ejaculation. In: Wein AJ. Campbell-Walsh Urology. 9th ed. Philadelphia, Pa.: Saunders; 2007. http://www.mdconsult.com/das/book/body/183878068-3/0/1445/25.html?tocnode=54301266&fromURL=25.html#4-u1.0-B978-0-7216-0798-6..50024-8_1829. Accessed Feb. 9, 2010.
  3. Heidelbaugh JJ. Management of erectile dysfunction. American Family Physician. 2010;81:305.
  4. Qaseem A, et al. Hormonal testing and pharmacologic treatment of erectile dysfunction: A clinical practice guideline from the American College of Physicians. Annals Internal Medicine. 2009;151:639.
  5. Buying Medicine Online. National Association of Boards of Pharmacy. http://www.nabp.net. Accessed Feb. 16, 2010.
MC00029 April 1, 2010

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