Foscarnet Injection
Foscarnet Injection is an intravenous (IV) antiviral used to treat CMV retinitis in people with AIDS and acyclovir-resistant mucocutaneous herpes simplex virus (HSV) infections in people with weakened immune systems.
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 10 clinical label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
Foscarnet Injection (Foscavir) is a specialist IV antiviral, available as a generic, usually held in reserve for CMV retinitis in people with AIDS and acyclovir-resistant herpes (HSV) sores in people with weakened immune systems; it blocks the enzyme the virus uses to copy its DNA, without needing viral enzymes to activate it first. It is one of the harder antivirals to tolerate, with nausea, vomiting, fever and headache common. The boxed warning covers kidney damage (the reason for fluids with every infusion and frequent blood tests) and drops in calcium and magnesium that can cause seizures, so report tingling around the mouth or numb hands or feet right away.
Clinical pearls
- It runs slowly on an infusion pump, never as a quick push, and needs diluting when given through an arm vein.
- Make sure prescribers know you are on it, since amphotericin B, aminoglycosides, tacrolimus and IV pentamidine add kidney or calcium risk.
- It can disturb heart rhythm (QT prolongation), so expect ECGs and avoid amiodarone, sotalol and certain antibiotics alongside it.
- If you need a water pill, thiazides are preferred, since loop diuretics can slow how fast the kidneys clear foscarnet.
⚠️ FDA Boxed Warning — the FDA’s strongest safety alert ▾
Foscarnet can seriously damage the kidneys. Your kidney function must be checked often, your dose adjusted, and you must stay well hydrated.
It can also upset blood minerals and electrolytes, which can cause seizures. Your care team will watch for these changes and may give mineral or electrolyte supplements. Report tingling around the mouth, numbness in your hands or feet, or any unusual symptoms right away.
Foscarnet is meant only for people with weakened immune systems who have CMV retinitis or acyclovir-resistant mucocutaneous HSV infections.
Patient information guide A plain-language walkthrough of Foscarnet Injection, written from its FDA label.
What Foscarnet Injection is used for
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Foscarnet Injection is an antiviral used for these conditions:
- CMV retinitis (cytomegalovirus infection of the eye) in people with AIDS
- CMV retinitis that returned after treatment with foscarnet or ganciclovir alone, using both drugs together
- Acyclovir-resistant mucocutaneous HSV infections in people with weakened immune systems
How Foscarnet Injection works
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Foscarnet blocks the virus's DNA polymerase, an enzyme the virus needs to copy its genetic material. It does this at levels that don't affect the body's own DNA enzymes.
Unlike some antivirals, it doesn't need to be activated by viral enzymes first.
Foscarnet Injection dosage
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Foscarnet is given by IV infusion through a pump, at a controlled slow rate. Dosing is individualized by weight, kidney function and the condition being treated.
- Induction treatment usually lasts a few weeks.
- CMV retinitis is followed by once-daily maintenance treatment.
- Fluids are given before and during infusions to protect the kidneys.
Dosing details from the FDA-approved label
From the Foscarnet Injection prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.
- CMV retinitis - induction treatment (normal renal function)
- Either 90 mg/kg (1-1/2 to 2 hour infusion) every twelve hours or 60 mg/kg (minimum one hour infusion) every eight hours over 2 to 3 weeks depending on clinical response
- Maximum: The rate of controlled intravenous infusion must be no more than 1 mg/kg/minute
- All doses must be individualized for renal function; hydration recommended before and during treatment
- Acyclovir-resistant HSV - induction treatment (normal renal function)
- 40 mg/kg (minimum one hour infusion) either every 8 or 12 hours for 2 to 3 weeks or until healed
- Maximum: The rate of controlled intravenous infusion must be no more than 1 mg/kg/minute
- All doses must be individualized for renal function; infusion pump must be used
- CMV retinitis - maintenance treatment
- 90 mg/kg/day to 120 mg/kg/day (individualized for renal function) given as an intravenous infusion over 2 hours
- Most patients should be started at 90 mg/kg/day
- Maximum: 120 mg/kg/day
- Escalation to 120 mg/kg/day may be considered should early re-induction be required because of retinitis progression
- Patients with abnormal renal function
- Dose must be adjusted per the Table 13 dosage guide based on creatinine clearance (mL/min/kg)
- E.g. maintenance 90 mg/kg/day equivalent is 90 Q24h for CrCl > 1.4
- If creatinine clearance falls below 0.4 mL/min/kg, discontinue, hydrate and monitor daily; not recommended in patients undergoing hemodialysis
Read the label’s full dosing text
DOSAGE AND ADMINISTRATION CAUTION - DO NOT ADMINISTER FOSCARNET SODIUM INJECTION BY RAPID OR BOLUS INTRAVENOUS INJECTION. THE TOXICITY OF FOSCARNET SODIUM INJECTION MAY BE INCREASED AS A RESULT OF EXCESSIVE PLASMA LEVELS. CARE SHOULD BE TAKEN TO AVOID UNINTENTIONAL OVERDOSE BY CAREFULLY CONTROLLING THE RATE OF INFUSION. THEREFORE, AN INFUSION PUMP MUST BE USED. IN SPITE OF THE USE OF AN INFUSION PUMP, OVERDOSES HAVE OCCURRED. ADMINISTRATION Instructions for Administration and Preparation Foscarnet sodium injection is administered by controlled intravenous infusion, either by using a central venous line or with dilution by using a peripheral vein. The rate of controlled intravenous infusion must be no more than 1 mg/kg/minute. An individualized dose of foscarnet sodium injection should be calculated on the basis of body weight (mg/kg), renal function, indication of use and dosing frequency (refer to DOSAGE subsection). To reduce the risk of nephrotoxicity, creatinine clearance (mL/min/kg) should be calculated even if serum creatinine is within the normal range, and doses should be adjusted accordingly. An individualized dose at the required concentration (24 mg/mL or 12 mg/mL) for the route of administration (central line or peripheral line) needs to be aseptically prepared prior to dispensing. The standard 24 mg/mL solution may be used with or without dilution when using a central venous catheter for infusion. When a peripheral vein catheter is used, the 24 mg/mL injection must be diluted to a 12 mg/mL concentration with 5% dextrose in water or with a normal saline solution prior to administration to avoid local irritation of peripheral veins. Dilutions and/or removals of excess quantities should be accomplished under aseptic conditions. Solutions thus prepared should be used within 24 hours of first entry into a sealed bottle or infusion bag. Hydration Hydration may reduce the risk of nephrotoxicity. Clinically dehydrated patients should have their condition corrected before initiating foscarnet sodium injection therapy. It is recommended that 750 to 1,000 mL of normal saline or 5% dextrose solution should be given prior to the first infusion of foscarnet sodium injection to establish diuresis.
Excerpted — the section continues on the label. Read the full Dosage and Administration section on DailyMed →
Foscarnet Injection side effects
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Common side effects seen in clinical trials include:
Common side effects
- Fever
- Nausea
- Vomiting
- Diarrhea
- Headache
- Anemia (low red blood cells)
- Abnormal kidney function
- Low potassium, calcium or magnesium levels
When to get medical help
- Seizures, or tingling around the mouth, numbness or tingling in the arms or legs (possible signs of low calcium)
- Signs of kidney problems, such as changes in urination
- Signs of a serious allergic reaction, such as hives, swelling or trouble breathing
- Fast or irregular heartbeat, fainting or dizziness (possible QT prolongation, a heart rhythm problem)
- Chest pain during an infusion
- Signs of low blood counts, such as unusual infections or bleeding
Foscarnet Injection warnings and precautions
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- Kidney damage is the major risk. Monitoring and hydration are essential.
- Electrolyte and mineral changes can cause tingling, seizures or heart rhythm problems.
- Seizures are more likely with kidney problems, low calcium or nervous system conditions.
- Serious allergic reactions have been reported.
- QT prolongation can lead to a dangerous heart rhythm, so ECGs are checked.
Foscarnet Injection interactions
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Foscarnet can clash with several drugs that affect the kidneys, calcium or the heart rhythm.
- IV pentamidine: low calcium and kidney problems
- Kidney-harming drugs such as aminoglycosides, amphotericin B, cyclosporine, acyclovir, methotrexate and tacrolimus: added kidney risk
- QT-prolonging drugs such as quinidine, procainamide, dofetilide, amiodarone and sotalol: heart rhythm risk
- Loop diuretics: may slow foscarnet clearance
- Ritonavir, with or without saquinavir: abnormal kidney function
Interactions listed in the FDA-approved label
From the Foscarnet Injection prescribing information (“Drug Interactions”): what the manufacturer studied or reported to the FDA.
- Intravenous pentamidine: Concomitant use may have caused hypocalcemia (one patient died with severe hypocalcemia), and renal impairment and symptomatic hypocalcemia have been observed. Extreme caution is advised when used concurrently with drugs that influence serum calcium levels; avoid combination with potentially nephrotoxic drugs unless benefits outweigh risks.
- Aerosolized pentamidine: Toxicity associated with concomitant use has not been reported.
- Potentially nephrotoxic drugs (aminoglycosides, amphotericin B, cyclosporine, acyclovir, methotrexate, tacrolimus): Because of foscarnet's tendency to cause renal impairment, there is added risk of renal toxicity. Avoid use in combination unless the potential benefits outweigh the risks to the patient.
- Diuretics (thiazides vs loop diuretics): Loop diuretics inhibit renal tubular secretion and may impair elimination of foscarnet, potentially leading to toxicity. When diuretics are indicated, thiazides are recommended over loop diuretics.
- Ritonavir, or ritonavir and saquinavir: Abnormal renal function has been observed in clinical practice during concurrent use. See DOSAGE AND ADMINISTRATION.
- QT-prolonging agents (Class IA antiarrhythmics such as quinidine or procainamide; Class III such as dofetilide, amiodarone, sotalol; phenothiazines, tricyclic antidepressants, certain macrolides and fluoroquinolones): Risk of QT prolongation and potential for torsades de pointes. Avoid use in combination.
Read the label’s full interactions text
Drug Interactions A possible drug interaction of foscarnet sodium injection and intravenous pentamidine has been described. Concomitant treatment of four patients in the United Kingdom with foscarnet sodium injection and intravenous pentamidine may have caused hypocalcemia; one patient died with severe hypocalcemia. Toxicity associated with concomitant use of aerosolized pentamidine has not been reported. Because foscarnet sodium injection can reduce serum levels of ionized calcium, extreme caution is advised when used concurrently with other drugs known to influence serum calcium levels (e.g., intravenous pentamidine). Renal impairment and symptomatic hypocalcemia have been observed during concurrent treatment with foscarnet sodium injection and intravenous pentamidine. Because of foscarnet's tendency to cause renal impairment, the use of foscarnet sodium injection should be avoided in combination with potentially nephrotoxic drugs such as aminoglycosides, amphotericin B, cyclosporine, acyclovir, methotrexate, tacrolimus and intravenous pentamidine (see above) unless the potential benefits outweigh the risks to the patient. When diuretics are indicated, thiazides are recommended over loop diuretics because the latter inhibit renal tubular secretion, and may impair elimination of foscarnet sodium injection, potentially leading to toxicity. Abnormal renal function has been observed in clinical practice during the use of foscarnet sodium injection and ritonavir, or foscarnet sodium injection, ritonavir, and saquinavir. (See DOSAGE AND ADMINISTRATION .) Because of the risk of QT prolongation and the potential for torsades de pointes, the use of foscarnet sodium injection should be avoided in combination with agents known to prolong the QT interval including Class IA (e.g., quinidine or procainamide) or Class III (e.g., dofetilide, amiodarone, sotalol) antiarrhythmic agents, phenothiazines, tricyclic antidepressants, and certain macrolides and fluoroquinolones.
Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.
Before taking Foscarnet Injection
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- Not for people who have had a significant allergic reaction to foscarnet.
- Use with caution with kidney problems; doses must be adjusted.
- Not recommended during hemodialysis.
- Use caution with low calcium or other electrolyte problems, seizure disorders or heart conditions.
- Not shown to be safe or effective in people with healthy immune systems.
Foscarnet Injection overdose
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Overdoses have occurred even with infusion pumps. They can cause seizures, kidney problems, tingling in the limbs or around the mouth, and electrolyte imbalances, mainly of calcium and phosphate. There is no specific antidote. Hemodialysis and hydration may help, and patients are watched for kidney and electrolyte problems.
How your body processes Foscarnet Injection
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Foscarnet is given by IV infusion. Its half-life in plasma is about 3 to 4 hours, though a longer terminal half-life suggests it is released slowly from bone. It reaches the cerebrospinal fluid and clears mainly through the kidneys. With reduced kidney function, clearance falls and levels stay higher, so dose adjustment is needed.
How to store Foscarnet Injection
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Store at 20° to 25°C (68° to 77°F). Protect from excessive heat (above 40°C) and from freezing. refrigerated or exposed to temperatures below the freezing point, precipitation may occur.
Written from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
Supplements & herbs that interact with Foscarnet Injection
12 supplements and herbal products have documented interactions with Foscarnet Injection in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.
- Major · 2
- Moderate · 9
- Minor · 1
Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.
Nutrient depletion considerations
Foscarnet Injection has been associated with lower levels of 1 nutrient in the clinical literature. This does not mean a deficiency will occur — it means these may be worth discussing with your pharmacist or healthcare provider, especially with long-term use.
Educational information from a licensed clinical database (Natural Medicines) — not medical advice. Do not start or stop medications or supplements without professional guidance.
Foscarnet Injection: pharmacist answers to common questions
Quick, plain-English answers to the questions patients ask most about Foscarnet Injection — the kind of thing our pharmacy team would talk through with you at the counter.
What is foscarnet used for?
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How will I receive it?
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Why do I need so many blood tests?
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What symptoms should I report right away?
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Can I take other medicines with it?
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What side effects are most common?
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Is Foscarnet Injection available over the counter?
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When was Foscarnet Injection first available?
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Who makes Foscarnet Injection?
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Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
More about Foscarnet Injection on HelloPharmacist
Foscarnet Injection forms and strengths (how it comes)
Foscarnet Injection is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Need a version that does not list lactose, a gluten source, a dye or gelatin? Inactive ingredients differ by manufacturer: see Foscarnet Injection inactive ingredients by manufacturer.
Injection
How this form is used
- Foscarnet sodium injection is used for CMV retinitis in people with AIDS.
- Foscarnet sodium injection is used for acyclovir-resistant mucocutaneous HSV infections in people with weakened immune systems.
- Foscarnet sodium injection is given as a controlled IV infusion with an infusion pump, never as a rapid injection.
- Foscarnet sodium injection can be given through a central line, or diluted for a peripheral vein.
- Foscarnet sodium injection should not be mixed with ganciclovir or run in the same line as other drugs.
Foscarnet Injection on the U.S. market: products, makers and brands
How Foscarnet Injection appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
10 companies list 10 Foscarnet Injection product records with the FDA, mostly as injection; the earliest marketing or approval year on record is 1991. Brand names on the directory include Foscavir; the rest are generics.
Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
How widely Foscarnet Injection is used (Medicaid data)
A general measure of how commonly Foscarnet Injection is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.
Think of this as a proxy for how widely Foscarnet Injection is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.
How commonly is Foscarnet Injection prescribed? Of the 1,601 medications we measure, Foscarnet Injection ranks #1,512 by Medicaid prescriptions — more than 6% of them.
Utilization by Foscarnet Injection product
Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.
250 ML foscarnet sodium 24 MG/ML Injection
Summed across the 2 of 18 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1734377
Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.
Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Foscarnet Injection, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 2 of 18 listed Foscarnet Injection NDCs with Medicaid activity.
Compare Foscarnet Injection products
A representative set of FDA-listed product records for Foscarnet Injection — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Injection | ||||
| 24 mg/mL | Intravenous | Amneal Pharmaceuticals LLC | ANDA | View NDC → |
| 6000 mg/250 mL | Intravenous | Baxter Healthcare Corporation | ANDA | View NDC → |
| 24 mg/mL | Intravenous | Caplin Steriles Limited | ANDA | View NDC → |
| 24 mg/mL | Intravenous | Clinigen Limited | NDA | View NDC → |
| 24 mg/mL | Intravenous | Fresenius Kabi USA, LLC | ANDA | View NDC → |
| 24 mg/mL | Intravenous | Gland Pharma Limited | ANDA | View NDC → |
| 24 mg/mL | Intravenous | Heritage Pharmaceuticals Inc. d/b/a Avet Pharmaceuticals Inc. | ANDA | View NDC → |
| 24 mg/mL | Intravenous | Hikma Pharmaceuticals USA Inc. | ANDA | View NDC → |
| 24 mg/mL | Intravenous | Sagent Pharmaceuticals | ANDA | View NDC → |
| 24 mg/mL | Intravenous | Somerset Therapeutics, LLC | ANDA | View NDC → |
Showing 10 of 10 products — FDA National Drug Code Directory. See every product, package size and price: browse all 10 Foscarnet Injection NDCs →
Foscarnet Injection side effects reported to the FDA (FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Foscarnet Injection — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Foscarnet Injection in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
Foscarnet Injection FDA approval history
How Foscarnet Injection went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
Foscarnet Injection recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
The FDA’s enforcement reports list no Foscarnet recalls since July 2021.
✅No Foscarnet recalls on record since July 2021Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Sep 24, 2026.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 33562 1 dose form · 1 strength
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Dose form (SCDF) Injection RxCUI 1734376In current FDA listingsClinical drug / strength (SCD) 250 ML foscarnet sodium 24 MG/MLRxCUI 1734377
Look up RxCUI 33562 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
Foscarnet Injection supply and shortage status
Whether Foscarnet Injection is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
Foscarnet Injection brand names
Foscarnet Injection is sold under one brand name in the FDA directory — Foscavir. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.
Who makes Foscarnet Injection: manufacturers and labelers
10 companies list Foscarnet Injection products with the FDA. By number of product records, the largest are Amneal Pharmaceuticals LLC, Baxter Healthcare Corporation, Caplin Steriles Limited. Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.
Foscarnet Injection drug class (RxNorm)
Foscarnet Injection belongs to the Pyrophosphate Analog DNA Polymerase Inhibitor class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
Sources for this Foscarnet Injection page
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How this page is built
HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. Clinigen Limited is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →