Skip to main content
Foscarnet Coupon - Foscarnet 250ml of 6000mg/250ml bottle of solution

foscarnet

Generic Foscavir
Used for CMV, Herpes

Foscarnet (Foscavir) is an antiviral used to treat cytomegalovirus (CMV) retinitis, an eye condition, in people with acquired immunodeficiency syndrome (AIDS). It's also used to treat certain types of herpes simplex virus (HSV) infections in people with weakened immune systems. It's given as an intravenous (IV) infusion by a trained healthcare provider, typically in a hospital setting. Your provider will closely monitor your kidney health and electrolyte levels through blood work while you're receiving foscarnet (Foscavir).

Reviewed by:
reviewerKristianne Hannemann, PharmD
reviewerAllison Gourley, PharmD
Last reviewed on September 24, 2023
basics-icon

What is Foscarnet (Foscavir)?

What is Foscarnet (Foscavir) used for?

  • Cytomegalovirus (CMV) retinitis in people with AIDs
  • Herpes simplex virus (HSV) infection that didn't respond well to acyclovir, in people with weakened immune systems

How Foscarnet (Foscavir) works

Foscarnet (Foscavir) is an antiviral that works by blocking a protein the virus needs to make copies of itself and spread in your body.

Drug facts

Common BrandsFoscavir
Drug ClassAntiviral
Controlled Substance ClassificationNot a controlled medication
Generic StatusNo lower-cost generic available
AvailabilityPrescription only
side-effects-icon

Side effects of Foscarnet (Foscavir)

The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.

Common Side Effects

Less Common Side Effects

  • Seizures
  • Feeling tired
  • Chills
  • Weakness
  • Dizziness
  • Tinging in arms and legs
  • Uncontrolled muscle movements
  • Confusion
  • Rash

Foscarnet (Foscavir) serious side effects

Contact your healthcare provider immediately if you experience any of the following.

  • Seizures
  • Abnormal heart rhythm (QT prolongation): chest pounding, trouble breathing, chest pain, feeling faint or lightheaded
  • Kidney damage: urinating less often than usual, swelling in your feet, ankles, or hands, unexplained weight gain, itchy skin
  • Electrolyte changes: tingling around the mouth, numbness, prickling sensation, muscle weakness or spasms, skipping heartbeats
  • Serious allergic reaction: swelling the face or throat, rash, trouble breathing

Source: DailyMed

The following Foscarnet (Foscavir) side effects have also been reported

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur:

More common

Increased or decreased frequency of urination or amount of urine

increased thirst

Less common

Chills

convulsions

fever

muscle twitching

pain at the injection site

pain or numbness in hands or feet

tingling sensation around the mouth

tremor

unusual tiredness and weakness

Rare

Sores or ulcers on the mouth or throat, penis, or vulva

Incidence not known

Difficulty with breathing or swallowing

fainting

hives or welts, itching, or skin rash

irregular heartbeat recurrent

large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs

nausea

reddening of the skin, especially around the ears

swelling of the eyes, face, or inside of the nose

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Abdominal or stomach pain

anxious feeling

confusion

dizziness

headache

loss of appetite

nausea and vomiting

unusual tiredness or weakness

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

pros-and-cons-icon

Pros and cons of Foscarnet (Foscavir)

Pros

  • Can be used to treat HSV infections when other antivirals, such as acyclovir, didn't work well
  • Maintenance dose for CMV retinitis is given once daily
  • Possible treatment option for people with liver problems

Cons

  • Each infusion can take 1 to 2 hours
  • Only available as an IV infusion
  • Raises risk of kidney damage and seizures
pharmacist-tips-icon

Pharmacist tips for Foscarnet (Foscavir)

pharmacist
  • It's important for your provider to closely monitor you for side effects while taking foscarnet (Foscavir). This medication can cause changes in your electrolytes, kidney damage, and heart problems. Your provider might need to adjust your dose or stop it altogether if you experience side effects.
  • Foscarnet (Foscavir) infusions might irritate your veins, especially if it's infused in the veins of the hand or arm. Your provider will try to minimize this risk by diluting it with IV fluids. Let your care team know if you notice any redness, swelling, or pain where the medication is being infused and they can try to ease your discomfort.
  • It's important to stay well-hydrated while receiving foscarnet (Foscavir) to prevent kidney damage and other side effects. Your provider will help make sure you're getting enough fluids during your treatment.
  • Since foscarnet (Foscavir) contains sodium (salt), it's important to let your provider know if you're on a low sodium diet.
  • Don't drive or operate machinery while you're receiving foscarnet (Foscavir) until you know how it affects you. This medication can cause dizziness, drowsiness, and seizures, which can lead to accidents.
faq-icon

Common questions about Foscarnet (Foscavir)

Your healthcare provider will give you foscarnet (Foscavir) as a slow infusion (over 1 to 2 hours) through either a central line or through the veins in the hand or arm. In addition, they'll also give you IV fluids before and with each dose of foscarnet (Foscavir) to lower your risk of serious side effects, such as kidney damage or electrolyte problems.

No. Foscarnet (Foscavir) isn't a cure for CMV eye infection or HSV infections. While you might fully heal from an active outbreak after receiving foscarnet (Foscavir), the virus still remains in your body. Most of the time, the virus will be stay dormant and not cause any problems. But it can get triggered in the future and cause outbreaks again. It's important to keep up with all of your appointments and have regular eye exams so your provider can check to see if your infection has come back after treatment.

It's not recommended to use foscarnet (Foscavir) if you're on hemodialysis because there isn't enough information to know which doses are safe to use, if any. Talk with your provider about safer options for you to use to treat your infection.

There isn't enough information to know if foscarnet (Foscavir) is safe to use during pregnancy. If you're pregnant or thinking of becoming pregnant, speak to your provider about the risks and benefits of this medication.

Foscarnet (Foscavir) hasn't been well-studied in children, so it isn't known if it's safe or works well in them. But animal studies show that the medication can cause problems in teeth and bones of growing animals. Because of this, providers might only consider foscarnet (Foscavir) for children if the benefits clearly outweigh the risks of harm.

Both foscarnet (Foscavir) and valganciclovir (Valcyte) are antiviral medications used to treat CMV eye infection in people with AIDs. But valganciclovir (Valcyte) is a first-choice treatment option because it has a lower risk of serious side effects compared to foscarnet (Foscavir). Your provider might consider foscarnet (Foscavir) instead if you're experiencing side effects from valganciclovir (Valcyte) and if you don't have any kidney problems. Valganciclovir (Valcyte) is taken by mouth, whereas foscarnet (Foscavir) is only available as an IV infusion.

educational-icon

How to save using GoodRx

Compare Prices
1. Compare PricesSpecify your dosage and quantity to find out exactly how much you can save.
Select your free coupon
2. Select your free couponYou can use the displayed coupon, or compare prices at other pharmacies near you.
Show coupon to your pharmacist
3. Show coupon to your pharmacistPresent your printed or electronic coupon when you pick up your prescription.
Get free couponLearn more
warnings-icon

Risks and warnings for Foscarnet (Foscavir)

Foscarnet (Foscavir) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.

Kidney damage

  • Risk factors: Lower fluids in the body | Older adults | Taking other medications that harm the kidneys | Receiving foscarnet (Foscavir) infusions too quickly

Warning Icon Foscarnet (Foscavir) can cause serious harm to the kidneys, especially in older adults. This is typically seen during the second week of treatment, but can happen at any time. The risk is higher for people who are dehydrated (not enough fluids in the body) or take other medications that can harm the kidneys. Your provider will give you IV fluids during treatment to minimize kidney damage. They'll also order blood work to check your kidney health. If your labs show changes in your kidney health, your provider might lower your dose of foscarnet (Foscavir) or stop it altogether.

Electrolyte changes and seizures

  • Risk factors: Taking a higher dose of foscarnet (Foscavir) | Receiving foscarnet (Foscavir) infusions too quickly | Kidney problems | History of seizures

Warning Icon Foscarnet (Foscavir) can cause changes to your electrolyte levels, including low calcium, low magnesium, and low potassium levels. In some cases, this can be life-threatening and have also led to seizures. Your provider will regularly monitor your electrolyte levels and provide treatment if needed. Tell your care team if you experience tingling in your arms or legs, muscle spasms, or numbness since these can be signs of electrolyte problems.

Severe allergic reaction

In some rare cases, foscarnet (Foscavir) can cause severe allergic reactions. If you notice a rash, trouble breathing, or swelling in your face or throat, get medical attention right away.

Heart rhythm problems (QT prolongation)

  • Risk factors: Older adults | Low blood potassium or magnesium levels | Kidney problems | Heart rate or heart rhythms problems | Taking other medications that can cause QT prolongation

Foscarnet (Foscavir) can affect your heart rhythm, which can be serious and life-threatening. One example includes lengthening the time period from when the heart pumps and then relaxes. This is known as QT prolongation. Your risk for QT prolongation is higher if you currently have heart or electrolyte problems, or are taking other medications that can cause heart rhythm problems. Your provider will check your heart with an electrocardiogram (ECG) before and during treatment. If you feel your chest pounding, have trouble breathing or chest pain, or feel faint or lightheaded while taking foscarnet (Foscavir), get medical help right away.

Low blood cell counts

  • Risk factors: Taking other medications that affect blood cell count | Kidney problems

Foscarnet (Foscavir) can lower your blood cell counts, including red blood cells and white blood cells. This can make you feel more tired or make it harder for your body to fight new infections. Your provider will order blood tests regularly and might change your dose of foscarnet (Foscavir). In some cases, your provider might stop the medication altogether if your blood counts become too low.

dosage-icon

Foscarnet (Foscavir) dosage

Typical dosage for Foscarnet (Foscavir)

Your provider will calculate the dose of foscarnet (Foscavir) based on your body weight. This medication is typically given as a slow infusion into the veins (IV) by a trained healthcare provider in a hospital or clinic setting.

  • Treatment of CMV eye infection

    • Starting dose: The typical dose is 90 mg/kg given IV every 12 hours, or 60 mg/kg given every 8 hours. Treatment with the starting dose usually lasts 2 to 3 weeks, depending on your condition.
    • Maintenance dose: The typical dose is 90 mg/kg given IV once daily. If needed, your provider might raise your dose to 120 mg/kg once daily. Your provider will determine when you can stop your infusions.

  • Treatment of herpes simplex virus: The typical dose is 40 mg/kg given IV every 8 to 12 hours for 2 to 3 weeks or until healed.

Your dose might differ if you have kidney problems.

interactions-icon

Interactions between Foscarnet (Foscavir) and other drugs

Foscarnet (Foscavir) may interact with certain medications or supplements. Always let your doctor and pharmacist know about any other medications or supplements (including prescribed and over-the-counter medications, vitamins, and dietary or herbal supplements) that you are currently taking. The list below does not include all possible drug interactions with Foscarnet (Foscavir). Please note that only the generic name of each medication is listed below.

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are receiving this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

alternatives-icon

What are alternatives to Foscarnet (Foscavir)?

There are a number of medications that your doctor can prescribe in place of Foscarnet (Foscavir). Compare a few possible alternatives below.
Foscarnet (Foscavir)
Used for:
  • Cytomegalovirus (CMV) retinitis in people with AIDs
  • Herpes simplex virus (HSV) infection that didn't respond well to acyclovir, in people with weakened immune systems
View prices
Used for:
  • Prevention of cytomegalovirus (CMV) infection after organ transplant
  • Treatment of CMV eye infection in adults with acquired immunodeficiency syndrome (AIDS)
$88.96Lowest GoodRx priceView prices
Used for:
  • Cytomegalovirus (CMV) retinitis in people with AIDs
$228.25Lowest GoodRx priceView prices
images-icon

Foscarnet (Foscavir) images

colorless - Foscarnet Sodium 6000mg/250mL Solution for Injection
This medicine is Colorless Bottle Of Solution.colorless - Foscarnet Sodium 6000mg/250mL Solution for Injection

Get savings updates for Foscarnet (Foscavir)

Receive price alerts, news, and other messages from GoodRx about Foscarnet (Foscavir) and other healthcare topics and relevant savings offers.

By providing your email, you consent to receive marketing communications from GoodRx, which may include content and/or data related to men's health, women's health, reproductive care, or sexual health. You agree to the GoodRx Terms of Use and acknowledge the Privacy Policy. You can unsubscribe at any time.

References

Best studies we found

Baxter Healthcare Corporation. (2023). Foscarnet sodium injection, solution [package insert]. DailyMed.

Beyer, K., et al. (2017). Outpatient foscarnet administration incorporating home infusions is feasible greatly enhancing the care of hematopoietic stem cell transplant recipients. Transplantation and Cellular Therapy.

ClinicalInfoHIV.gov. (2023). Cytomegalovirus disease.

GoodRx Health has strict sourcing policies and relies on primary sources such as medical organizations, governmental agencies, academic institutions, and peer-reviewed scientific journals. Learn more about how we ensure our content is accurate, thorough, and unbiased by reading our editorial guidelines.

Was this page helpful?