Sildenafil (Viagra®)

Last Modified: April 20, 2012

Pronounced: sil-DEN-a-fil
Classification: Phosphodiesterase Inhibitor

About Sildenafil

Sildenafil is a medication that is taken before sexual activity and allows men with erectile dysfunction (ED) to achieve and maintain an erection. ED or impotence is a condition in which a man is unable to achieve or maintain an erection long enough for sexual intercourse. This can be a result of medical conditions such as high blood pressure, diabetes, prostate problems, and heart disease, or a side effect of the medications typically taken for these conditions. Personal lifestyle factors such as stress, alcohol and/or tobacco use can also play a contributing role. During surgery or radiation to the pelvic area (including prostate, bladder, and rectal procedures), damage can occur to the nerves that supply the penis. This can result in either temporary or permanent impotence. Some surgeons perform "nerve-sparing" surgeries in an attempt to preserve erectile function. Even in these cases, however, the nerves will suffer some injury, and it can take 18-24 months or longer for erectile function to return. These men should be treated aggressively with oral or injectable medications for ED in order to speed recovery of the nerves and to prevent muscle wasting in the penis.

How to Take Sildenafil

Sildenafil citrate is taken by mouth up to once a day, at least 30-60 minutes before sexual activity, and works for up to 4 hours. Your doctor will determine the dose that is best for you. Some men require dose adjustments to find the dose that works best for them. You should not adjust your dose without talking to your doctor first. Sildenafil works best on an empty stomach. Do not take this medication after a high-fat meal.

Men who take nitrates, such as nitroglycerin, Nitro-Bid, Isordil, or Deponit should not take sildenafil. Men who take Cardura, Hytrin, or Flomax for urinary symptoms should also not take sildenafil.

Possible Side Effects of Sildenafil

These are some of the most common side effects:

Headache, facial flushing and upset stomach can occur. Less frequent side effects include blurry vision, a bluish hue to the field of vision, a sensitivity to light, or sudden loss of vision.

If you experience any of the following while using sildenafil citrate, you should seek immediate medical attention:

  • An erection lasting more than 4 hours
  • Chest, arm or neck pain, or nausea during sexual activity
  • Sudden loss of vision

Do not take a higher dose of sildenafil citrate than your doctor orders for you.

Remember, sildenafil citrate does not protect against sexually transmitted diseases, nor does it prevent pregnancy.


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