North American Coral Snake Antivenin
Antivenin (Micrurus fulvius)
Also known as: North American Coral Snake Antivenin · Antivenin (Micrurus fulvius)
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Coral Snake envenomation | 1-2 vials initially, and more in 4-6 hours if necessary | IV | initially, and more in 4-6 hours if necessary | — | 🌎 NA |
| Coral Snake envenomation | 1-2 vials of antivenin. Initially give one vial, by diluting to 100-250 mL of crystalloid fluids and initially administering by slow IV . In smaller patients, adjust infusion volume to prevent fluid overload. Give additional vials as indicated by the progression of the syndrome. | slow IV | Initially, then as indicated | — | 🌎 NA |
- Coral Snake envenomation: Therapy is best started within 4 hours after envenomation. Supportive care includes broad-spectrum antibiotics, fluid therapy and mechanical ventilation if necessary. Corticosteroids are not recommended.
- Coral Snake envenomation: Dose necessary is calculated relative to the amount of venom injected and the body mass of patient. Smaller patients may require higher doses (as venom amount/kg body weight is higher).
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Coral Snake envenomation | 1-2 vials of antivenin. Initially give one vial, by diluting to 100-250 mL of crystalloid fluids and initially administering by slow IV . In smaller patients, adjust infusion volume to prevent fluid overload. Give additional vials as indicated by the progression of the syndrome. | slow IV | Initially, then as indicated | — | 🌎 NA |
- Coral Snake envenomation: Dose necessary is calculated relative to the amount of venom injected and the body mass of patient. Smaller patients may require higher doses.
Horses
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Coral Snake envenomation (systemic effects) | Administer 1-2 vials slowly IV diluted in 250-500 mL saline or lactated Ringer's. | IV | Once, use only if necessary | — | 🌎 NA |
- Coral Snake envenomation (systemic effects): Use only if necessary to treat systemic effects, otherwise avoid use. Administer antihistamines; corticosteroids are contraindicated. May be used with Crotilidae antivenin.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
North American Coral Snake Antivenin is a life-saving antidote specifically formulated to treat envenomation from the Eastern coral snake (Micrurus fulvius fulvius) and the Texas coral snake (Micrurus fulvius tenere).
Important Clinical Pearl: This antivenin will NOT neutralize venom from the Sonoran/Arizona coral snake (Micruroides euryxanthus) or the Brazilian giant coral snake (Micrurus frontalis).
Unlike pit viper venom, which causes severe local tissue necrosis and coagulopathy, coral snake venom is primarily neurotoxic. Clinical signs of envenomation (such as ascending flaccid paralysis, loss of gag reflex, and respiratory failure) may be delayed by up to 12-24 hours. Therefore, any animal suspected of a coral snake bite should be hospitalized for close observation for at least 24-48 hours.
Mechanism of action
Antivenins provide passive immunity by supplying pre-formed neutralizing antibodies (globulins) derived from horses hyperimmunized with coral snake venom.
- Mechanism: The antibodies directly bind to the complex venom proteins (specifically alpha-neurotoxins) in the patient's bloodstream.
- Pathway: Venom-antibody binding → prevents neurotoxins from attaching to nicotinic acetylcholine receptors at the neuromuscular junction → halts the progression of flaccid paralysis and respiratory depression.
- Each vial neutralizes approximately 2 mg of M. fulvius fulvius venom.
Safety & warnings
Contraindications
- Envenomation by Sonoran or Arizona Coral Snake (Micruroides euryxanthus)
Adverse effects
- Hypersensitivity reactions
- Anaphylaxis (incidence <2%)
- Anaphylactoid reactions
- Serum sickness
- Erythema and wheal formation (at injection site during sensitivity testing)
Precautions
Anaphylaxis Risk: High risk of hypersensitivity reactions due to the equine serum origin.
- Sensitivity Testing: A 1:10 dilution given intracutaneously (0.02-0.03 mL) may be used to test for hypersensitivity (wheal/erythema within 30 mins indicates a positive reaction). Note: A negative test does not guarantee anaphylaxis won't occur.
- Pretreatment: Diphenhydramine is often recommended prior to administration.
- Management: If an anaphylactoid reaction occurs, stop the infusion, give additional diphenhydramine, and restart 5 minutes later at a slower rate.
- Pregnancy: FDA Category C.
Drug interactions
May mask the clinical signs associated with the venom; use initially with caution.
Theoretical potentiation of venom, though undocumented. Diphenhydramine is routinely used by clinicians for pretreatment.
May mask the early signs associated with anaphylaxis.
Contraindicated for the treatment of snakebite envenomation itself, but may be useful to treat secondary anaphylaxis.
Monitoring
- Signs associated with an allergic response to the antivenin (anaphylaxis, anaphylactoid-reactions, serum sickness)
- Cardiorespiratory monitoring
- Mechanical ventilation parameters (if necessary)
- Pulse oximetry
Overdose
Specific overdosage information is not provided, but in smaller patients, care must be taken to adjust the infusion volume of the crystalloid diluent to prevent fluid overload.
Available products
Formulations
- Powder for Injection lyophilized (with diluent)
Human-labeled
- Antivenin (Micrurus fulvius) Powder for Injection lyophilized: in single-use vials with 1 vial diluent (10 mL water for injection) (Ayerst)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Product should be stored in the refrigerator. Avoid freezing and excessive heat. Reconstitute vial with 10 mL of the supplied diluent. Gentle agitation may be used to hasten dissolution of the lyophilized powder. Reconstituted vials should be used within 48 hours (keep refrigerated) and within 12 hours once added to IV solutions.
Client information
If you suspect your pet has been bitten by a coral snake, seek emergency veterinary care immediately.
- Delayed Symptoms: Coral snake venom causes severe nerve damage, and symptoms (like weakness, inability to swallow, or breathing difficulty) may not appear for 12 to 24 hours. Your pet will need to be hospitalized and closely monitored for 1 to 2 days.
- Allergic Reactions: Because this antidote is made using horse serum, there is a risk of a severe allergic reaction (anaphylaxis). Your vet will monitor closely for this and may give medications to prevent it.
- Cost: Treatment for coral snake bites, including the antivenin, intensive care, and potentially a mechanical ventilator to help your pet breathe, can be very expensive.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.