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Foscarnet injection

Foscarnet is an antiviral medication that treats and prevents infections causes by viruses like herpes and cytomegalovirus (CMV). CMV is an illness you get from a type of herpes virus, which is an organism that uses your cells to make more copies of itself. A healthcare provider will give you this medication through an infusion into a vein.

What is this medication?

FOSCARNET (fos KAR net) is an antiviral medicine. It is used to treat or prevent infections caused by certain kinds of viruses. Examples of these infections include herpes and cytomegalovirus (CMV).

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This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.

COMMON BRAND NAME(S): Foscavir

What should I tell my care team before I take this medication?

They need to know if you have any of these conditions:

  • heart disease
  • high levels of phosphorus in the blood
  • kidney disease
  • low blood counts, like white cell, platelets, or red cell counts
  • low levels of calcium, magnesium, phosphorus, or potassium in the blood
  • seizures
  • an unusual or allergic reaction to foscarnet, other medicines, drugs, dyes, or preservatives
  • pregnant or trying to get pregnant
  • breast-feeding

How should I use this medication?

This medicine is for infusion into a vein. It is given by a health care professional in a hospital or clinic setting.

Talk to your pediatrician regarding the use of this medicine in children. Special care may be needed.

Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.

NOTE: This medicine is only for you. Do not share this medicine with others.

What if I miss a dose?

This does not apply.

What may interact with this medication?

Do not take this medicine with any of the following medications:

  • cidofovir
  • cisapride
  • dronedarone
  • pimozide
  • thioridazine

This medicine may also interact with the following medications:

  • aspirin and aspirin-like medicines
  • cisplatin
  • cyclosporine
  • diuretics
  • dofetilide
  • medicines for infection like acyclovir, adefovir, amphotericin B, bacitracin, ganciclovir, gentamicin, pentamidine, vancomycin
  • methotrexate
  • NSAIDs, medicines for pain and inflammation, like ibuprofen or naproxen
  • other medicines that prolong the QT interval (cause an abnormal heart rhythm)
  • pamidronate
  • ritonavir
  • saquinavir
  • tacrolimus
  • ziprasidone
  • zoledronic acid

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This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.

What should I watch for while using this medication?

Visit your doctor or health care professional for regular checkups. Discuss any new symptoms with your doctor. Your vision and blood may be tested before and during use of this medicine.

Check with your doctor or health care professional if you get an attack of severe diarrhea, nausea and vomiting, or if you sweat a lot. The loss of too much body fluid can make it dangerous for you to take this medicine.

Tell your doctor right away if you have any tingling or numbness in your mouth or in your arms or legs. This may be a sign of a serious problem.

You may get drowsy or dizzy. Do not drive, use machinery, or do anything that needs mental alertness until you know how this medicine affects you. Do not stand or sit up quickly, especially if you are an older patient. This reduces the risk of dizzy or fainting spells.

What side effects may I notice from receiving this medication?

Side effects that you should report to your doctor or health care professional as soon as possible:

  • allergic reactions like skin rash, itching or hives, swelling of the face, lips, or tongue
  • breathing problems
  • changes in vision
  • dizziness
  • fast or irregular heartbeat
  • fever or chills, sore throat
  • numb, tingling pain
  • pain, swelling at site where infused
  • seizures
  • trouble passing urine or change in the amount of urine
  • unusual bleeding or bruising
  • unusually tired or weak

Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):

  • anxious
  • depressed mood
  • diarrhea
  • headache
  • loss of appetite
  • nausea, vomiting
  • stomach pain
  • weight loss

This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Where should I keep my medication?

Keep out of the reach of children.

If you are using this medicine at home, you will be instructed on how to store this medicine. Throw away any unused medicine after the expiration date on the label.

NOTE: This sheet is a summary. It may not cover all possible information. If you have questions about this medicine, talk to your doctor, pharmacist, or health care provider.

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Note: Introduction and Additional Common Questions written and medically approved by Cleveland Clinic professionals.

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