What symptoms of a poisonous snake bite does Anavip help with?

Anavip works as an antivenom by neutralizing and removing the venom from your body. As a result, it can improve some [symptoms from a poisonous snake bite](https://www.merckmanuals.com/home/injuries-and-poisoning/bites-and-stings/snakebites), such as pain, weakness, dizziness, and nausea. In addition, Anavip can also [lower the risk](https://www.sciencedirect.com/science/article/pii/S0041010122000137) of abnormal bleeding and clotting due to the snake venom that can happen days after the bite. Typically, symptoms start to improve within [2 infusions](https://anavip-us.com/) of Anavip. Because Anavip attaches to the venom to neutralize its effect, make sure to get treatment as soon as possible, before the venom has the chance to spread.

How long does Anavip stay in your system?

It can take [about a month](https://www.sciencedirect.com/science/article/pii/S0041010122000137) for most of Anavip to leave your body. Keep in mind that this time frame is estimated based on the [half-life](https://www.goodrx.com/drugs/medication-basics/drug-half-life) of the medication. Since Anavip stays in your system longer, it can continue to neutralize the snake bite venom and help your body remove it after you get discharged from the hospital.

Anavip

crotalidae immune f(ab)2

Used for Venom Poisoning

Anavip, also known as crotalidae immune F(ab')2 (equine), is an antivenom that’s used for snake bites from certain types of North American pit vipers. Anavip is given in the hospital as an injection through the vein (also called intravenous or IV). The medication should be given as soon as possible after the snake bite, even if there are no symptoms. The most common side effects of Anavip include itchiness and nausea.

Reviewed by:

Ally Tsai, PharmD

Cydnee Ng, PharmD

Last reviewed on November 13, 2023

What is Anavip?

What is Anavip used for?

Bites from certain poisonous North American pit viper snakes (e.g., copperheads, rattlesnakes, cottonmouths)

How Anavip works

Anavip works as an antivenom for certain types of pit viper snake bites. It contains proteins that attach to the snake venom in your body. Once attached, the medication neutralizes the venom and helps the body quickly remove it from your system. As a result, symptoms from the venom, such as itching, nausea, and rash.

Are you looking for information on CroFab (crotalidae polyvalent immune Fab) instead?

Drug facts

Common BrandsAnavip

Drug ClassAntivenom

Controlled Substance ClassificationNot a controlled medication

Generic StatusNo lower-cost generic available

AvailabilityPrescription only

Side effects of Anavip

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

Itching (43%)
Nausea (23%)
Rash (12%)
Joint pain (11%)
Swelling in arms, legs, or feet (8%)
Muscle pain (7%)
Vomiting (6%)
Headache (6%)
Pain in arms or legs (6%)

Less Common Side Effects

Skin redness
Skin blister
Chills
Fever
Anxiety
Trouble sleeping
Dehydration
Shortness of breath

Anavip serious side effects

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

Allergic reaction: hives, rash, trouble breathing, chest tightness, wheezing, low blood pressure

Source: DailyMed

Pros and cons of Anavip

Pros

Can use in people of all ages
Can control most symptoms of venom poisoning within 4 hours
Can be prepared and quickly given within minutes
Can prevent further symptoms of venom poisoning for up to 8 days

Cons

Might not be safe for people with allergies to horse protein
Commonly causes skin reactions, like itching and rash
Need injections every hour until symptoms get better
Can only be given at certain hospitals, which requires transportation and potential delays to treatment

Pharmacist tips for Anavip

After you get Anavip injections, you might still be at risk for unusual bleeding or clotting from the snake bite for a few weeks. Lower your risk for bleeding by avoiding contact sports, dental procedures, tattoos, piercings, and surgery for as long as 2 weeks after treatment.
Call a provider if you have any unusual bruising or bleeding (e.g., bleeding from the gums after brushing teeth, nosebleeds) or other serious bleeding. These can be late signs of venom poisoning. The provider might decide to treat you with Anavip again or with other medications to help stop or prevent further problems.
Contact a healthcare provider if you have allergic reactions to Anavip after you've been discharged from the hospital. Watch out for symptoms such as rash, itchiness, fever, muscle pain, and joint pain. Your provider might prescribe antihistamines or corticosteroids to help relieve symptoms.
Certain medications, such as NSAIDs (nonsteroidal anti-inflammatory drugs), might raise your risk of bleeding. Talk to your provider first before you use any over-the-counter (OTC) medications. Your provider can make sure these medications are safe for you to take.
Your healthcare team will follow up with you after you leave the hospital to make sure you’re recovering well from your snake bite. You might need to do follow-up lab work so your care team can check for your risk for late signs of venom poisoning and make sure your blood work is normal. Be sure to get your blood tests done as instructed after you've been discharged.
To help your snake bite heal after you're treated with Anavip, be sure to take extra care of the bite site. Keep it clean to prevent infection, and take any newly prescribed medications as instructed. Speak with your healthcare team about whether physical therapy or home exercises would help improve movement of the bitten limb.

Common questions about Anavip

Both CroFab and Anavip are given in the hospital as antivenoms. They're both used to treat snake bites from poisonous pit vipers. One difference is that Anavip stays in the body longer than CroFab does. This means that you might be at lower risk for abnormal bleeding or clotting from the snake venom after treatment with Anavip than with CroFab. In fact, Anavip can prevent late venom effects for up to 8 days.

Anavip works as an antivenom by neutralizing and removing the venom from your body. As a result, it can improve some symptoms from a poisonous snake bite, such as pain, weakness, dizziness, and nausea. In addition, Anavip can also lower the risk of abnormal bleeding and clotting due to the snake venom that can happen days after the bite. Typically, symptoms start to improve within 2 infusions of Anavip. Because Anavip attaches to the venom to neutralize its effect, make sure to get treatment as soon as possible, before the venom has the chance to spread.

It can take about a month for most of Anavip to leave your body. Keep in mind that this time frame is estimated based on the half-life of the medication. Since Anavip stays in your system longer, it can continue to neutralize the snake bite venom and help your body remove it after you get discharged from the hospital.

Anavip only works for bites from venomous North American pit vipers (snakes), which include rattlesnakes, copperheads, and cottonmouths. Get medical attention right away if you get bitten by a snake. Try to take a picture of the snake from a safe distance, if possible. This can help your healthcare team quickly identify the right treatment for your snake bite.

It's not clear how safe Anavip is if you’re pregnant or breastfeeding. There aren't any studies that look at whether this medication can cause birth defects to unborn babies or whether it ends up in breast milk. Make sure your healthcare team is aware that you’re pregnant or breastfeeding as soon as possible. This will help your care team decide whether Anavip is necessary for you.

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Risks and warnings for Anavip

Anavip 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.

Allergic reactions

Risk factor: Horse protein allergy

Anavip can sometimes cause allergic reactions. You might be more likely to have an allergic reaction to this medication if you have allergies to horse proteins. This is because Anavip is made using horse blood products.

Symptoms of an immediate allergic reaction include hives, rash, trouble breathing, chest tightness, wheezing, low blood pressure, and anaphylaxis. Since you’re typically in the hospital when these reactions happen, your care team will monitor you closely and quickly give you appropriate treatment. Otherwise, call for help right away if you have these allergic reactions.

Other times, delayed reactions can happen after you’ve gone home from the hospital. You might have a fever, rash, itchiness, and aches in your muscles or joints. It’s important to watch out for these symptoms and call your healthcare provider as soon as possible if you experience them.

Possible risk of serious infections

Since Anavip is made from horse blood products, it can potentially carry viruses or harmful proteins that can make you sick. Typically, blood products like Anavip are thoroughly purified so they meet high manufacturing standards to lower your risk. Let your provider know right away if you think that you've developed an infection as a result of this medication.

Possible reactions to cresol

Risk factors: History of allergic reaction to cresols

Anavip might contain a small amount of a chemical called cresol. This chemical is considered an inactive ingredient in Anavip. Some people have reported having reactions or muscle pain when they used other injections containing cresol as an inactive ingredient. Watch out for itching, swelling or redness around the site of injection or muscle pain.

Anavip dosage

Typical dosage for Anavip

Anavip is only available as an IV infusion that's administered by a healthcare provider. The dose depends on how poisonous the venom is, what symptoms of venom poisoning the person has, and how soon the person can get medical attention (ideally, as soon as possible).

The typical starting dose is 10 vials injected through the veins over a 1-hour period. Each vial of Anavip contains up to 120 mg of medication.

If you're still having symptoms an hour after the first dose, your healthcare team will inject additional doses (each consisting of 10 vials) through the veins every hour until your symptoms get better.

Once your symptoms start to improve after the first dose(s), your healthcare team will monitor you in the hospital for at least 18 more hours. If symptoms return, you'll be given 4 vials through the veins as needed.

What are alternatives to Anavip?

There are a number of medications that your doctor can prescribe in place of Anavip. Compare a few possible alternatives below.

Anavip

Used for:

Bites from certain poisonous North American pit viper snakes (e.g., copperheads, rattlesnakes, cottonmouths)

View prices

CroFab

Used for:

Bites from certain venomous North American pit viper snakes (e.g., copperheads, rattlesnakes, cottonmouths)

View prices

Anavip images

This medicine is Colorless Vial.

References

Best studies we found

Agency for Toxic Substances and Disease Registry. (2021). Cresols.

Barish, R. A., et al. (2022). Snakebites. Merck Manual Consumer Version.

Buchanan, J. T., et al. (2022). Crotalidae envenomation. StatPearls.

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.

Anavip