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Foscarnet

Generic Name: foscarnet (fos-KAR-net)
Brand Name: Foscavir

Foscarnet may cause kidney damage or seizures. Notify your doctor immediately if you experience a change in the amount of urine. It is important you receive appropriate amounts of fluid (hydration) when foscarnet is used. Your doctor will monitor your blood and kidneys while you are using foscarnet.

Foscarnet is only approved for use in people with a weak immune system to treat eye problems caused by cytomegalovirus (CMV). It is also used to treat a type of herpes simplex virus (HSV) infection that cannot be treated by another medicine. Discuss any questions or concerns with your doctor.


Foscarnet is used for:

Treating eye problems caused by CMV in people with AIDS. It is also used to treat a type of HSV that cannot be treated by another medicine in people with a weak immune system. It may also be used for other conditions as determined by your doctor.

Foscarnet is an antiviral agent. It works by inhibiting the growth and reproduction of viruses, which helps fight off infections caused by viruses.

Do NOT use foscarnet if:

  • you are allergic to any ingredient in foscarnet
  • you have certain heart problems or you are on a low-sodium diet
  • you are on hemodialysis

Contact your doctor or health care provider right away if any of these apply to you.

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Before using foscarnet:

Some medical conditions may interact with foscarnet. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:

  • if you are pregnant, planning to become pregnant, or are breast-feeding
  • if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
  • if you have allergies to medicines, foods, or other substances
  • if you have central nervous system problems, blood electrolyte problems (eg, calcium, phosphate, magnesium, potassium), heart problems, or kidney problems
  • if you are dehydrated or have a blood problem (eg, anemia, low white blood cell counts)
  • if you have a history of seizures

Some MEDICINES MAY INTERACT with foscarnet. Tell your health care provider if you are taking any other medicines, especially any of the following:

  • Pentamidine because the risk of low blood calcium levels may be increased. Deaths have also happened when foscarnet was used with pentamidine
  • Loop diuretics (eg, furosemide) because they may increase the risk of foscarnet's side effects
  • Acyclovir, aminoglycoside antibiotics (eg, gentamicin), amphotericin B, cyclosporine, methotrexate, ritonavir, saquinavir, tacrolimus, or other medicines that may harm the kidney because the risk of kidney side effects may be increased. Check with your doctor if you are unsure if any of your medicines may harm the kidney
  • Medicines that may change the amount of calcium in your blood because the risk of low blood calcium levels may be increased. Check with your doctor if you are unsure if any of your medicines may change the amount of calcium in your blood

This may not be a complete list of all interactions that may occur. Ask your health care provider if foscarnet may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.

How to use foscarnet:

Use foscarnet as directed by your doctor. Check the label on the medicine for exact dosing instructions.

  • Foscarnet is given as an injection at your doctor's office, hospital, or clinic. Contact your health care provider if you have any questions.
  • Drinking extra fluids while you are taking foscarnet is recommended. Check with your doctor for instructions.
  • If you miss a dose of foscarnet, contact your doctor right away.

Ask your health care provider any questions you may have about how to use foscarnet.

Important safety information:

  • Foscarnet may cause dizziness. This effect may be worse if you take it with alcohol or certain medicines. Use foscarnet with caution. Do not drive or perform other possibly unsafe tasks until you know how you react to it.
  • If you have seizures, dizziness, or drowsiness while using foscarnet, do not drive or perform other possibly unsafe tasks. Discuss any questions or concerns with your doctor.
  • Foscarnet is not a cure for CMV infection, and eye inflammation may progress during and after treatment.
  • Foscarnet is not a cure for HSV infections. While complete healing is possible, the infection may return.
  • Seizures have happened with foscarnet. Sometimes, deaths have happened with seizures. Discuss any questions or concerns with your doctor.
  • Foscarnet may irritate the vein. It may burn the skin if the medicine leaks from the vein when it is given. Tell your nurse if you have any redness, burning, pain, swelling, or leaking of fluid where the medicine is going into your body.
  • Lab tests, including eye exams, kidney function tests, and electrolyte levels, may be performed while you use foscarnet. These tests may be used to monitor your condition or check for side effects. Be sure to keep all doctor and lab appointments.
  • Safety and effectiveness in CHILDREN have not been confirmed. Use foscarnet with caution if it is given to a child. Talk with the doctor.
  • PREGNANCY and BREAST-FEEDING: If you become pregnant, contact your doctor. You will need to discuss the benefits and risks of using foscarnet while you are pregnant. It is not known if this medicine is found in breast milk. Do not breast-feed while taking foscarnet.

Possible side effects of foscarnet:

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome:

Anxiety; decreased appetite; diarrhea; dizziness; headache; nausea; stomach pain; sweating; tiredness; vomiting; weakness.

Seek medical attention right away if any of these SEVERE side effects occur:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); burning, numbness, or tingling; depression; genital ulcers or irritation; not able to control muscle movements; seizures; shortness of breath; symptoms of fluid and electrolyte problems (eg, mood changes; confusion; muscle cramps, pain, spasms, or weakness; numbness or tingling around the mouth or in the arms or legs; fast or irregular heartbeat; seizures; loss of appetite; severe nausea or vomiting; severe dizziness or fainting; more thirst; dry mouth or eyes); symptoms of infection (eg, fever, chills, cough, sore throat); symptoms of kidney problems (eg, not able to pass urine, change in how much urine is passed, blood in the urine, big weight gain); unusual tiredness or weakness; vision changes.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. To report side effects to the appropriate agency, please read the Guide to Reporting Problems to FDA.

If OVERDOSE is suspected:

Contact 1-800-222-1222 (the American Association of Poison Control Centers), your local poison control center, or emergency room immediately.

Proper storage of foscarnet:

Foscarnet will be handled and stored by a health care provider. You will not store it at home. Keep all medicines out of the reach of children and away from pets.

General information:

  • If you have any questions about foscarnet, please talk with your doctor, pharmacist, or other health care provider.
  • Foscarnet is to be used only by the patient for whom it is prescribed. Do not share it with other people.
  • If your symptoms do not improve or if they become worse, check with your doctor.
  • Check with your pharmacist about how to dispose of unused medicine.

This information should not be used to decide whether or not to take foscarnet or any other medicine. Only your health care provider has the knowledge and training to decide which medicines are right for you. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about foscarnet. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to foscarnet. This information is not specific medical advice and does not replace information you receive from your health care provider. You must talk with your healthcare provider for complete information about the risks and benefits of using foscarnet.

Issue Date: June 3, 2015
Database Edition 15.2.1.003
Copyright © 2015 Clinical Drug Information, LLC

Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only your health care provider has the knowledge and training to decide which medicines are right for you. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from your health care provider. You must talk with your healthcare provider for complete information about the risks and benefits of using this medicine.

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