Sildenafil (Injection)


Sildenafil (sil-DEN-a-fil)

Treats pulmonary arterial hypertension (high blood pressure in the lungs).

Brand Name(s)


When This Medicine Should Not Be Used

How to Use This Medicine


  • Your doctor will prescribe your dose and schedule. This medicine is given through a needle placed in a vein.
  • A nurse or other health provider will give you this medicine.

Drugs and Foods to Avoid

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

  • Make sure your doctor knows if you are using medicine for high blood pressure (such as amlodipine, doxazosin, terazosin, Cardura®, Hytrin®, or Norvasc®). Tell your doctor if you are also using cimetidine (Tagamet®), an antibiotic (such as erythromycin, EES®, or Erytab®), medicine to treat HIV or AIDS (such as ritonavir, Norvir®), or medicine to treat fungus infections (such as itraconazole, ketoconazole, Nizoral®, or Sporanox®).

Warnings While Using This Medicine

  • Make sure your doctor knows if you are pregnant or breastfeeding, or if you have lung disease, diabetes, high cholesterol, a stomach ulcer, problems with the retina in your eyes (retinitis pigmentosa), or if your penis has an abnormal shape. Also tell your doctor if you are currently taking bosentan.
  • Your doctor needs to know if you have heart disease, a bleeding disorder, or problems related to your blood cells. This includes chest pain, high or low blood pressure, sickle cell anemia, or cancer of the blood (such as leukemia or multiple myeloma). Tell your doctor if you have had a heart attack, stroke, or uneven heartbeats in the last six months.
  • Do not take Viagra® or other similar medicines, such as tadalafil (Cialis®) or vardenafil (Levitra®). Viagra® also contains sildenafil. If you take too much sildenafil or take it together with these medicines, the chance for side effects will be higher.
  • Tell your doctor right away if you have a sudden loss of vision or a sudden decrease in hearing or loss of hearing. Hearing problems may also cause dizziness or ringing in the ears. These symptoms could be serious side effects from this medicine.
  • Your doctor needs to know if you are using medicine for high blood pressure. Sildenafil might lower your blood pressure. If your blood pressure gets too low, you might faint or have other health problems.
  • This medicine may cause the penis to become erect at unwanted times, or to stay erect for longer than needed. If you have an erection that lasts longer than 4 hours, call your doctor right away or go to an emergency room.
  • Your doctor will need to check your progress while you are receiving this medicine.

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, especially if it spreads to your jaw or arm.
  • Erection that is painful or lasts longer than 4 hours.
  • Fast, slow, or uneven heartbeat.
  • Fever, or sudden increase in body temperature.
  • Lightheadedness, dizziness, or fainting.
  • Nosebleeds.
  • Numbness, tingling, or burning pain in your hands, arms, legs, or feet.
  • Shortness of breath or troubled breathing.
  • 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.
  • Swelling in your hands, ankles, or feet.

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

  • Headache.
  • Joint or muscle pain.
  • Stuffy or runny nose.
  • Trouble with sleeping.
  • Upset stomach, diarrhea, nausea, 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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