Treatment algorithm

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

INITIAL

presumed snakebite

1st line – local wound care

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INITIAL
|
presumed snakebite
1st line – 

local wound care

Local wound care includes to rest and immobilize the bitten extremity and minimize exertion of the patient to delay centripetal spread of the venom.[31][32][33]​​ Complete immobilization is key in that movement of the extremity leads to centripetal spread of the venom. Potentially constricting objects (i.e., rings, bracelets) should be removed as subsequent soft tissue swelling may make later removal more difficult.[34]​

For venomous snakebites that do not cause local tissue damage and are neurotoxic (i.e., Elapidae or coral snakes) a pressure-immobilization bandage may be considered if the snake is definitively identified as a coral snake and not a crotaline or pit viper.[35] However, studies have demonstrated that medical personnel and lay rescuers have a low rate of applying such bandages at the appropriate pressure, which may limit their benefit.[34]​ An elastic bandage should be applied with 40 to 70 mmHg pressure for an upper limb or 55 to 70 mmHg pressure for a lower limb.[36]​​ A finger should be able to pass easily underneath the bandage. Elastic bandages may be superior to crepe bandages in maintaining an ideal pressure and preventing centripetal spread of venom.[37]

The use of pressure-immobilization bandages in snakebites that do cause local tissue damage (i.e., Crotalinae or pit vipers) should be avoided as it does not improve outcomes and may increase intracompartmental pressures in the bitten extremity.[34][38]​​

Plus – observation

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INITIAL
|
presumed snakebite
Plus – 

observation

Treatment recommended for ALL patients in selected patient group

If there is any uncertainty as to whether the bite was from a venomous snake, the patient should be observed for 12 hours to assess for developing toxicity.

Elapidae envenomation may initially be asymptomatic, but if neurologic deficits develop they are difficult to reverse. Therefore, patients who are suspected of, but not confirmed as, having been bitten by the Texas coral snake or Eastern coral snake should be observed for 24 hours for signs and symptoms of envenomation and treated with antivenom as soon as such signs and symptoms develop.

ACUTE

confirmed snakebite

1st line – inspection of local wound and irrigation with saline solution

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ACUTE
|
confirmed snakebite
1st line – 

inspection of local wound and irrigation with saline solution

The wound should be inspected and thoroughly irrigated with normal saline to minimize the risk of infection.

As with other puncture wounds, primary closure with sutures or wound adhesive is thought to increase the risk of infection and is generally not performed.

Consider – anesthesia, wound exploration, and foreign body removal

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ACUTE
|
confirmed snakebite
Consider – 

anesthesia, wound exploration, and foreign body removal

Treatment recommended for SOME patients in selected patient group

Anesthesia may be obtained with a regional nerve block or local infiltration. Adequate anesthesia is necessary to allow thorough wound exploration. Any foreign bodies should be removed.

Consider – tetanus immunization

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ACUTE
|
confirmed snakebite
Consider – 

tetanus immunization

Treatment recommended for SOME patients in selected patient group

Any patient whose last tetanus booster was more than 5 years ago should receive tetanus immunization.

Consider – analgesia

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ACUTE
|
confirmed snakebite
Consider – 

analgesia

Treatment recommended for SOME patients in selected patient group

Pain may be treated with nonsteroidal anti-inflammatory drugs (NSAIDs) or with opioids if severe. Clinicians should use opioids cautiously in patients with hypotension and respiratory impairment because they may lead to further deterioration of the patient's condition.

NSAIDs should be avoided in patients with clinical or laboratory evidence of coagulopathy as they may increase the risk of hemorrhage.

Primary options

morphine sulfate: 2-4 mg intravenously every 5-15 minutes when required until pain is controlled

OR

fentanyl: 50 micrograms intravenously every 2 hours as needed for pain

OR

oxycodone: 5-10 mg orally (immediate-release) every 6 hours when required

OR

ibuprofen: 400-800 mg orally every 6-8 hours when required, maximum 2400 mg/day

OR

naproxen: 250-500 mg orally twice daily when required, maximum 1250 mg/day

OR

diclofenac potassium: 50 mg orally (immediate-release) twice or three times daily when required

OR

ketorolac: 10 mg orally every 6 hours for 3-5 days

Consider – antibiotics

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ACUTE
|
confirmed snakebite
Consider – 

antibiotics

Treatment recommended for SOME patients in selected patient group

The use of prophylactic antibiotics is not generally thought to be necessary. Prospective trials found that snakebite patients who do not receive prophylactic antibiotics do not develop wound infections, and suggest reserving antibiotics for cases where necrosis or signs of infection are present.[39][40][41][42]​ No infectious complications were noted in pediatric patients who abandoned prophylactic antibiotic treatment.[42]

The risk of snakebite infection in immunocompromised patients is not well defined, and the use of prophylactic antibiotics may be prudent.

If prophylactic antibiotics are indicated due to the presence of necrosis or signs of infection, wound cultures following snakebite infection predominantly grow gram-negative aerobic bacilli (primarily Enterobacteriaceae) and gram-positive aerobic cocci, so antibiotic therapy should be directed against these bacteria.

A total treatment duration of 7 to 10 days would be appropriate.

Primary options

cephalexin: 500 mg orally every 8 hours

OR

amoxicillin/clavulanate: 875 mg orally every 12 hours

More

Secondary options

cefazolin: 1000 mg intravenously every 6 hours

OR

vancomycin: 15 mg/kg intravenously every 12 hours

Plus – observation

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ACUTE
|
confirmed snakebite
|
domestic Crotalinae snakebite: local symptoms with no progression
Plus – 

observation

Treatment recommended for ALL patients in selected patient group

Patients with Crotalinae snakebites with minimal swelling at the bite site or without progressive worsening of local symptoms should be observed, and antivenom should not be administered.

Patients with local or systemic symptoms should be admitted to an intensive care setting to monitor for hypotension, bleeding, and compartment syndrome.

Patients bitten by crotalines other than the Mojave rattlesnake may be discharged after 8 to 12 hours of observation if they are asymptomatic. Patients bitten by the Mojave rattlesnake require observation for 12 to 24 hours because delayed neurotoxicity may occur.

Plus – intravenous Crotalidae antivenom

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ACUTE
|
confirmed snakebite
|
domestic Crotalinae snakebite: systemic manifestations or progressive local symptoms
Plus – 

intravenous Crotalidae antivenom

Treatment recommended for ALL patients in selected patient group

Crotalidae polyvalent immune Fab (ovine) antivenom (known as CroFab®) or Crotalidae immune F(ab’)2 (equine) antivenom (known as Anavip®) is indicated in all patients with systemic symptoms, laboratory derangements, or progressively worsening local symptoms.[20]

Some patients with initial improvement after CroFab® antivenom administration may experience a recurrent coagulopathy hours to days later.[47][48]​ In one study, medically significant delayed hemorrhage was reported in approximately 0.5% of North American crotaline snakebite victims treated with CroFab® antivenom.[49] These patients may benefit from repeat administration or use of the longer-acting Anavip®, if available.[50]

Clinicians should closely monitor patients for allergic reaction, including anaphylaxis, and serum sickness. Antivenom is contraindicated in patients with hypersensitivity to: CroFab® or Anavip® antivenom, other related antivenoms, papain, papaya, latex, dust mites, or any ingredient in the formulation. It should be used with caution in patients who have been previously treated with CroFab® or Anavip® antivenom. In patients with contraindications, the risk of antivenom administration must be weighed against the severity of envenomation.

The initial infusion should be started at a low rate (25-50 mL/hour) while assessing for any allergic reaction. If no allergic reaction occurs in the first 10-15 minutes, the rate of infusion may be increased.

After the initial infusion is complete, the treating clinician should assess whether initial control of the envenomation (defined as complete arrest of local manifestations and normalization of vital signs and coagulation parameters) has been attained.

If initial control has not been attained, the initial dose should be repeated until initial control has been achieved.

Primary options

Crotalidae polyvalent immune Fab (ovine): consult specialist for guidance on dose

OR

Crotalidae immune F(ab')2 (equine): consult specialist for guidance on dose

Consider – supportive care

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ACUTE
|
confirmed snakebite
|
domestic Crotalinae snakebite: systemic manifestations or progressive local symptoms
Consider – 

supportive care

Treatment recommended for SOME patients in selected patient group

Cardiogenic and noncardiogenic pulmonary edema may occur. Supplemental oxygen should be provided to maintain oxygenation. Patients with hypoxemia despite supplemental oxygen may require noninvasive positive pressure ventilation such as bi-level positive airway pressure. Endotracheal intubation and mechanical positive pressure ventilation may be necessary in severe pulmonary edema. Positive end-expiratory pressure may minimize atelectasis and improve oxygenation.

Crotalinae envenomation may, in some cases, cause severe coagulopathy leading to hemorrhage. Although reversal of coagulopathy generally occurs with antivenom administration, some patients may require transfusion of blood products such as platelets, packed red blood cells, or fresh frozen plasma. Routine repletion of clotting factors in patients with venom-induced consumption coagulopathy is controversial but may be associated with earlier improvement in coagulation function. It is unclear whether the improvement in coagulation function is associated with any clinical benefit.[54][55]

Hypotension secondary to capillary third-spacing or cardiac myotoxicity should be treated with fluid resuscitation and vasopressors.

Consider – intravenous antivenin North American coral snake

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ACUTE
|
confirmed snakebite
|
domestic Elapidae snakebite
Consider – 

intravenous antivenin North American coral snake

Treatment recommended for SOME patients in selected patient group

Patients who are known to have been bitten by the Texas coral snake or Eastern coral snake should receive antivenom even if they are asymptomatic.[1][26]​ Further doses of antivenom should be administered to patients who develop symptoms of envenomation.

Patients who have been bitten by the Arizona coral snake (also known as the Sonoran coral snake) generally develop only mild symptoms. Antivenom is not typically used.

The antivenom consists of equine immunoglobulin G. A history of atopy or allergy to horses or horse serum is a relative contraindication to the antivenom. A skin test to evaluate for allergic reaction to the antivenom should be performed prior to antivenom administration.

Vial administration is either by slow piggyback injection into a wide-open line of normal saline or by dilution in 250 mL of normal saline and running it wide-open.

When giving the initial dose, the treating clinician should start by infusing slowly while monitoring for allergic reaction.

Additional vials should be administered as needed to control signs or symptoms of Elapidae envenomation.

Primary options

North American coral snake (Micrurus fulvius) antivenin (equine): consult specialist for guidance on dose

Consider – supportive care

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ACUTE
|
confirmed snakebite
|
domestic Elapidae snakebite
Consider – 

supportive care

Treatment recommended for SOME patients in selected patient group

Elapidae envenomation may cause weakness culminating in respiratory paralysis.

Patients with an impaired ability to protect their airway or inadequate minute ventilation/oxygenation require endotracheal intubation and mechanical ventilation. In some cases, prolonged mechanical ventilation may be necessary until the patient regains use of the muscles of respiration.

Plus – observation, expert consultation, and zoo antivenom

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ACUTE
|
confirmed snakebite
|
exotic or non-native snakebite
Plus – 

observation, expert consultation, and zoo antivenom

Treatment recommended for ALL patients in selected patient group

Exotic snakebites and envenomations present unique problems. Difficulties with snake identification, and with procuring and administering antivenom, may all complicate management.

Close observation in an intensive care unit may prevent unexpected morbidity or mortality.

Early involvement of a herpetologist and a medical toxicologist may improve the quality of care provided.

In some cases, the snake involved is a pet or part of a collection and can be collected by animal control and identified by a herpetologist.

Antivenom for exotic snakes is not commercially available in the US and may be difficult to obtain. However, herpetologists, zoos, and certain specialist emergency services, such as the Miami-Dade Fire Rescue Venom Response Unit, have antivenom for a variety of exotic snakes. Miami-Dade Fire Rescue: Venom Response Unit Opens in new window

Foreign medical institutions may have antivenom for species native to their areas.

Consider – supportive care

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ACUTE
|
confirmed snakebite
|
exotic or non-native snakebite
Consider – 

supportive care

Treatment recommended for SOME patients in selected patient group

Envenomation by exotic snakes of the family Viperidae may cause systemic derangements similar to those caused by their Crotalinae relatives. Clinicians should be aware of the risks of pulmonary edema, hypotension, and coagulopathy and treat accordingly.

Envenomation by exotic Elapidae snakes may produce symptoms similar to those produced by domestic elapids.

Despite these potential similarities, clinicians must be aware that within a given family, subfamily, or genus there can be significant interspecies differences in venom composition and clinical effects.

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Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups. See disclaimer

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