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Foscavir

Generic name: foscarnetfos-KAR-net ]
Drug class: Miscellaneous antivirals

Medically reviewed by Drugs.com on Mar 11, 2024. Written by Cerner Multum.

What is Foscavir?

Foscavir is an antiviral medicine that prevents certain viruses from multiplying in your body.

Foscavir is used to treat cytomegalovirus (CMV) retinitis in people with AIDS.

Foscavir is also used to treat herpes simplex virus (HSV) in people with a weak immune system. This medicine is usually given for HSV after other antiviral medications have been tried without successful treatment.

Foscavir is not a cure for CMV or HSV, and your virus may progress during or after treatment.

Foscavir may also be used for purposes not listed in this medication guide.

Foscavir side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Foscavir may cause serious side effects. Call your doctor at once if you have:

Some of Foscavir leaves the body in urine, which can cause irritation when you urinate. You may also develop sores or ulcers around your urethra (the opening where urine passes out of your bladder). Drink plenty of fluids and take care to keep your genital area clean while receiving this medicine.

Common side effects of Foscavir may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Warnings

Foscavir can harm your kidneys. This effect is increased when you also use certain other medicines, including: antivirals, chemotherapy, injected antibiotics, medicine for bowel disorders, medicine to prevent organ transplant rejection, injectable osteoporosis medication, and some pain or arthritis medicines (including aspirin, Tylenol, Advil, and Aleve).

Your kidney function and electrolytes (potassium, sodium, magnesium, phosphorus) will need to be tested often.

Injecting Foscavir too fast can cause dangerous or unwanted side effects.

Before taking this medicine

You should not use Foscavir if you are allergic to it.

To make sure Foscavir is safe for you, tell your doctor if you have:

It is not known whether Foscavir will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

It is not known whether foscarnet passes into breast milk or if it could harm a nursing baby. You should not breast-feed while using this medicine.

How is Foscavir given?

Follow all directions on your prescription label. Your doctor may occasionally change your dose. Do not use this medicine in larger or smaller amounts or for longer than recommended.

Foscavir is injected into a vein through an IV using an infusion pump. The medicine enters the body through a catheter placed into the vein. A healthcare provider will show you how to use an infusion pump. Do not self-inject this medicine if you do not understand how to give the injection and properly dispose of used needles, IV tubing, and other items used to inject the medicine.

You may also be given IV fluids to keep you from getting dehydrated.

You may need to mix Foscavir with a liquid (diluent) before using it. If you are using the injections at home, be sure you understand how to properly mix and store the medicine. Do not give this medicine with other medicines in the same IV line.

Foscavir should be clear and colorless. Gently shake the medicine if appears to have separated. Do not use the medicine if it has changed colors or has particles in it. Call your pharmacist for new medicine.

The medicine must be injected slowly and can take up to 2 hours to complete. Injecting Foscavir too fast can cause dangerous or unwanted side effects.

Foscavir is usually given for 2 to 3 weeks. Follow your doctor's dosing instructions very carefully.

While using Foscavir, your kidney function and electrolytes (potassium, sodium, magnesium, phosphorus) will need to be tested often, and you may also need regular eye exams.

Store Foscavir at room temperature away from very hot or very cold temperature.

What happens if I miss a dose?

Call your doctor for instructions if you miss a dose of Foscavir.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while using Foscavir?

Avoid getting Foscavir in your eyes, as it may cause burning or irritation. If it does get into your eyes rinse with water and call your doctor.

This medicine may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.

What other drugs will affect Foscavir?

Foscavir can harm your kidneys. This effect is increased when you also use certain other medicines, including: antivirals, chemotherapy, injected antibiotics, medicine for bowel disorders, medicine to prevent organ transplant rejection, injectable osteoporosis medication, and some pain or arthritis medicines (including aspirin, Tylenol, Advil, and Aleve).

Tell your doctor about all your current medicines and any you start or stop using, especially:

This list is not complete. Other drugs may interact with foscarnet, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

acyclovir, valacyclovir, Valtrex, Zovirax, Valcyte, famciclovir, valganciclovir, Famvir, cidofovir, foscarnet

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.