Search Content

Foscarnet

Warning

This medication is used only for cytomegalovirus (CMV) eye infections and acyclovir-resistant herpes infections.

Foscarnet may cause serious side effects such as kidney problems and seizures due to mineral/electrolyte imbalance. You may be given fluids and/or minerals/electrolytes while receiving this medication. Your doctor should check your kidney function and lab tests while you are using this medication to decrease the risk of these side effects. Tell your doctor right away if you have any of signs of kidney problems or mineral/electrolyte imbalance, such as change in the amount of urine, numbness/tingling of arms/legs, tingling around the mouth, seizures, muscle cramps/spasms, mental/mood changes, weakness, or irregular heartbeat.

Precautions

Before using foscarnet, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: liver disease, kidney disease (including being on dialysis), dehydration, low electrolyte levels (calcium, magnesium, potassium, phosphate), nervous system problems (such as a history of seizures), a low sodium diet.

This drug may make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Children may be more sensitive to the side effects of this drug, especially the effects on developing bones.

Older adults may be more sensitive to the side effects of this drug, especially kidney problems.

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

It is unknown if this drug passes into breast milk. Because of the possible risk to the infant, breastfeeding is not recommended while using this drug. Consult your doctor before breastfeeding.

Side Effects

See also Warning section.

Nausea, vomiting, headache, diarrhea, dizziness, or swelling/pain at the injection site may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including: new vision problems, fast breathing, unusual tiredness, painful urination, irritation/sores on the penis, vaginal irritation/sores, signs of infection (such as sore throat that doesn't go away, fever).

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

RxAnswers™ is a copyrighted combined product from TraceGains and First DataBank, Inc.

Drug information is selected from data included with permission and copyrighted by First DataBank, Inc. This is a summary and does not contain all possible information about this product. For complete information about this product or your specific health needs, ask your healthcare professional. Always seek the advice of your healthcare professional if you have any questions about this product or your medical condition. This information is not intended as individual medical advice and does not substitute for the knowledge and judgment of your healthcare professional. This information does not contain any assurances that this product is safe, effective or appropriate for you.

This information is intended only for residents of the United States. Products sold under the same brand names in other countries may contain different ingredients.

Learn more about First DataBank

There are some limitations on the information provided in “Nutrient Interactions.” Do NOT rely solely on the information in this article. Please read the disclaimer.

Learn more about TraceGains, the company.

TraceGains and/or its suppliers make no warranties or representations as to the accuracy or completeness of this content herein or that of any organization referred or linked to within this content and will not be liable for any damages arising out of your access to or use of any information found herein or that of any organization referred to within this content.

Information expires December 2025.