Foscarnet (Injection)


Foscarnet (fos-KAR-net)

Treats infections caused by cytomegalovirus (CMV) in patients who have acquired immune deficiency (AIDS). Also treats herpes simplex virus (HSV) infections in the mucus membranes (nose, mouth, vagina, or rectum).

Brand Name(s)


When This Medicine Should Not Be Used

How to Use This Medicine


  • Your doctor will prescribe your exact dose and tell you how often it should be given.
  • Your medicine will be put directly into your body through one of your veins. This is called intravenous (in-tra-VEEN-us), or IV.
  • The medicine is usually given slowly over a period of 1 to 2 hours or more.
  • This medicine may damage your kidneys. To help prevent this, you may have extra liquids given intravenously before or with your treatment. Your doctor may also want you to drink extra liquids while you are being given this medicine.
  • Your treatment will be given by a nurse or other caregiver trained to give IV medicine. Sometimes you, a family member, or a friend can be taught to give your medicine.
  • Before your treatment, check your IV bag or bottle to make sure there are no leaks. The liquid should be clear and colorless (like water).

If a dose is missed:

  • This medicine needs to be given on a regular schedule. If you miss a dose, call your doctor for instructions.
  • You should not use two doses at the same time.

How to Store and Dispose of This Medicine

  • You should not use the medicine if it is colored or has lumps or solid pieces in it.
  • Store the medicine at room temperature. Do not let it freeze or get too cold.
  • If you have your treatments at home, you should be given a special container for the used needles, tubes, and IV bags. Keep it where children and pets cannot reach it.
  • Keep all medicine out of the reach of children.

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 also taking zidovudine (AZT, Retrovir┬«), amikacin, gentamicin, netilmicin, tobramycin, vancomycin, amphotericin B (Fungizone┬«), or pentamidine (Pentam┬«) injections.

Warnings While Using This Medicine

  • Before using this medicine, make sure your doctor knows if you have kidney disease, anemia, seizures, or low levels of calcium in your body (hypocalcemia).
  • If you are pregnant or breastfeeding, talk to your doctor before taking this medicine. You should not breastfeed if you have HIV or AIDS, because you may give the infection to your baby through your breast milk.
  • Foscarnet will not cure CMV infections or HSV infections, but may slow the progress of these diseases.
  • If you are getting this medicine for a CMV eye infection, it is important for you to have your eyes checked regularly. Keep all appointments your eye doctor makes for you.
  • Your doctor may want to test your blood on a regular schedule while you are getting this medicine. Keep all appointments your doctor makes for you.
  • Foscarnet may lower the amounts of calcium and other minerals in your body. If these levels get too low, you may feel tingling around your mouth or numbness, pain, or tingling in your hands and feet. If you have these symptoms, call your doctor right away.
  • Do not get the medicine on your skin. If this does happen, rinse the area well with water and tell your caregiver.
  • This medicine may make you dizzy. If it does, avoid driving or using machinery.

Possible Side Effects While Using This Medicine

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

  • Sudden decrease in urine amounts or urinating less than one cup in a day
  • Pain, tingling, or numbness in your hands or feet or tingling around your mouth
  • Unexplained fever, chills, or sore throat
  • Unusual bleeding or bruising
  • Seizures
  • Severe skin rash
  • Pain, redness, or swelling where the IV is given
  • Sores on the penis or vulva

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

  • Headache, dizziness
  • Nausea, vomiting, diarrhea, appetite loss
  • Confusion, nervousness

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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