Sildenafil (By mouth)


Sildenafil (sil-DEN-a-fil)

Treats erectile dysfunction (trouble having an erection). Also treats pulmonary arterial hypertension (high blood pressure in the lungs).

Brand Name(s)

Revatio, Viagra

When This Medicine Should Not Be Used

How to Use This Medicine


  • Take your medicine as directed.
  • For erectile dysfunction: Take this medicine about 60 minutes (1 hour) before you have sex. Do not take it more than once a day. Always allow at least 24 hours between doses.
  • For pulmonary arterial hypertension: Take this medicine 3 times a day, 4 to 6 hours apart.
  • Read and follow the patient instructions that come with this medicine. Talk to your doctor or pharmacist if you have any questions.
  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.

Drugs and Foods to Avoid

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Do not use this medicine if you also use a nitrate medicine, often used to treat angina (chest pain) or high blood pressure. Nitrate medicines include nitroglycerin, isosorbide, amyl nitrate, butyl nitrate, and nitrite.
  • Some medicines can affect how sildenafil works. Tell your doctor if you are using the following:
    • amlodipine
    • cimetidine
    • medicine for prostate problems or high blood pressure (alfuzosin, doxazosin, prazosin, silodosin, tamsulosin, terazosin)
    • medicine to treat HIV or AIDS (atazanavir, indinavir, ritonavir, saquinavir)
    • medicine to treat infections (erythromycin, itraconazole, ketoconazole)
    • rifampin

Warnings While Using This Medicine

  • Tell your doctor if you are pregnant or breastfeeding, or if you have kidney disease, liver disease, a bleeding disorder, blood problems (such as leukemia, multiple myeloma, sickle cell anemia), diabetes, heart disease, heart failure, high cholesterol, high or low blood pressure, a stomach ulcer, vision or eye problem, or a penis with an abnormal shape. Tell your doctor if you smoke.
  • Tell your doctor if you have ever had chest pain during sex, or if you had a stroke or heart attack within the past 6 months.
  • If you take this medicine for pulmonary arterial hypertension, do not take Viagra┬« or other similar medicines, such as tadalafil or vardenafil. Viagra┬« also contains sildenafil.
  • It is important that you tell all of your doctors that you take sildenafil. If you need emergency medical care for a heart problem, it is important that your doctor knows when you last took sildenafil.
  • This medicine may cause the following problems:
    • Low blood pressure (especially if taken with other medicines that lower blood pressure)
    • Painful or prolonged erection
  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Possible Side Effects While Using This Medicine

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Chest pain, trouble breathing, or sudden, severe headache
  • Erection that is painful or lasts longer than 4 hours
  • Fast, slow, pounding, or uneven heartbeat
  • Lightheadedness, dizziness, or fainting
  • Sudden changes in your vision or changes in how you see colors (especially blue or green)
  • Sudden decrease in hearing or hearing loss, ringing in the ears, or dizziness

If you notice these less serious side effects, talk with your doctor:

  • Headache
  • Nosebleeds
  • Tiredness or weakness
  • Upset stomach or indigestion
  • Warmth or redness in your face, neck, arms, or upper chest

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Version Info

  • Last reviewed on 8/4/2014

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