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Foscarnet (By injection)

Foscarnet (fos-KAR-net)

Treats cytomegalovirus (CMV) eye infection in patients with AIDS. Also treats herpes simplex virus infections in the nose, mouth, vagina, or rectum.

Brand Name(s):

Foscavir, Foscavir Novaplus

There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

This medicine is not right for everyone. You should not receive it if you had an allergic reaction to foscarnet.

How to Use This Medicine:


  • Your doctor will prescribe your dose and schedule. This medicine is given through a needle placed in a vein. This medicine is given slowly, so the needle will stay in place for 1 to 2 hours or longer.
  • A nurse or other health provider will give you this medicine.
  • Missed dose: Call your doctor or pharmacist for instructions.

Drugs and Foods to Avoid:

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

  • Some medicines can affect how foscarnet works. Tell your doctor if you are using any of the following:
    • Acyclovir, amphotericin B, cyclosporine, methotrexate, pentamidine, or tacrolimus
    • Aminoglycoside antibiotic
    • Diuretic (water pill)
    • Medicine to treat depression
    • Medicine to treat heart rhythm (including amiodarone, dofetilide, procainamide, quinidine, sotalol)
    • Medicine to treat an infection
    • Phenothiazine medicine

Warnings While Using This Medicine:

  • Tell your doctor if you are pregnant or breastfeeding, or if you have kidney disease, anemia, heart disease, a history of seizures, or if you are on a low sodium diet.
  • Do not breastfeed. You can spread HIV or AIDS to your baby through your breast milk.
  • This medicine may cause the following problems:
    • Kidney damage
    • Seizures
    • Electrolyte imbalances in your blood, such as low calcium, potassium, or magnesium
    • Heart rhythm problem (such as QT prolongation)
  • This medicine may make you dizzy or drowsy. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.
  • Drink extra fluids so you will urinate more often and help prevent kidney problems.
  • Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments. You will need regular eye exams if you are receiving this medicine for a CMV eye infection.

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
  • Decrease in how much or how often you urinate
  • Dry mouth, increased thirst, muscle cramps, nausea, vomiting
  • Fast, pounding, or uneven heartbeat
  • Fever chills, cough, sore throat, body aches
  • Muscle cramps or spasms, confusion
  • Pain, tingling, or numbness in your hands or feet or tingling around your mouth
  • Seizures
  • Unusual bleeding, bruising, tiredness, or weakness

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

  • Diarrhea
  • Headache
  • Irritation or sores in your genital area
  • Pain, itching, burning, swelling, or a lump under your skin where the needle is placed

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

Last Updated: 5/1/2020

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites.

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