Management of Snakebite

1. Initial Assessment - Is It a Venomous Bite?

• 20-25% of pit viper bites and up to 75% of sea snake bites are "dry bites" - no venom is released
• All bites should initially be treated as potentially venomous
• Key identification clues: triangular head, elliptical pupils, enlarged fangs, loreal pits (pit vipers), rattle (rattlesnakes)
• Coral snake rule (North America only): "Red and yellow, kill a fellow; red and black, venom lack" - this rule does NOT apply outside North America
• Do not attempt to catch, handle, or kill the snake - reflexive bites from dead snakes can occur

2. First Aid / Prehospital Management

• Move the patient away from the snake
• Immobilize the bitten limb in a neutral position, at or below heart level if significant swelling is present (above heart if minimal swelling, to reduce edema)
• Remove rings, watches, and tight clothing from the bitten extremity before swelling begins
• Transport rapidly to the nearest medical facility
• Keep the patient calm to minimize venom spread
• For neurotoxic elapid bites (especially Australian snakes, kraits): apply a pressure immobilization bandage - wrap the entire limb firmly (like a sprained ankle) from the bite site upward, then splint; this delays systemic absorption

• Apply tourniquets or constrictive bands (cause ischemia and worsen local tissue damage)
• Incise and suck the wound (ineffective and causes harm)
• Apply ice or cryotherapy
• Apply electric shock
• Give aspirin or NSAIDs (worsen coagulopathy and bleeding)
• Administer alcohol

Note: Pressure immobilization is appropriate for neurotoxic (elapid) bites but is contraindicated for cytotoxic/hemotoxic viper bites as it worsens local tissue necrosis.

3. Hospital Assessment

History

• Time of bite, snake description, symptoms since bite
• Allergies, medications, prior antivenom use (risk of hypersensitivity)

Physical Examination

• Mark the leading edge of swelling, ecchymosis, and erythema with pen and time
• Measure limb circumference at 3 points (bite site, proximal joint, distal joint) every 15 minutes until stabilized, then every 1-2 hours
• Assess for cranial nerve signs (ptosis, diplopia, dysphagia) - early signs of neurotoxic envenomation preceding respiratory failure
• Palpate axillary/inguinal lymph nodes (reflects lymphatic spread)
• Assess vital signs, cardiovascular status, airway

Envenomation Grading (Crotaline / Pit Viper)

4. Investigations

• CBC - assess hemorrhage, hemolysis, thrombocytopenia
• Blood type and cross-match
• Coagulation studies - PT/INR, aPTT, fibrinogen, fibrin degradation products (D-dimer)
• Renal and hepatic function (LFTs, BUN/creatinine)
• Creatine kinase - for rhabdomyolysis (especially sea snakes, Australian elapids)
• Urinalysis - blood, myoglobin, hemoglobin
• ECG and chest X-ray in severe envenomations

5. Antivenom - The Cornerstone of Treatment

Types

• Monospecific: against a single species
• Polyspecific: covers several species in a geographic region (e.g., VINS Polyvalent for India, covering all four "Big Four" species)

Indications for Antivenom

• Progressive local swelling crossing a joint or involving more than half the bitten limb
• Signs of systemic envenomation: hypotension, coagulopathy, neurotoxicity, rhabdomyolysis, hemolysis
• Abnormal coagulation (elevated PT, reduced fibrinogen, positive 20WBCT)
• Thrombocytopenia (<100,000/µL)
• Hemoglobinuria or myoglobinuria
• ECG abnormalities or arrhythmias

Administration

• Always give IV (intravenous only; IM is ineffective and dangerous)
• Dilute in normal saline (100-250 mL) and infuse slowly initially (over 15-30 minutes), watching for hypersensitivity reactions
• Skin testing before antivenom is unreliable and not recommended (false negatives are common)
• Have epinephrine, antihistamines, and corticosteroids at bedside before starting

Dosing

Antivenom Reactions

• Early anaphylactic reactions (within 10-180 min): urticaria, angioedema, bronchospasm, hypotension - treat with epinephrine IM/IV
• Late serum sickness (7-21 days): arthralgia, rash, fever, lymphadenopathy - treat with oral prednisolone for 5-7 days

6. Specific Envenomation Syndromes

Crotaline (Pit Viper) Envenomation

• Local effects: Intense pain, progressive edema, ecchymosis, blistering, tissue necrosis
• Systemic effects: Coagulopathy (fibrinogen depletion, thrombocytopenia), hypotension/shock (from plasma extravasation), neurotoxicity (some species, e.g., Mojave rattlesnake - ptosis, weakness)
• Treatment: Antivenom (CroFab or Anavip in US), supportive care, fluids for hypotension, FFP/platelets only if antivenom has been given and coagulopathy persists

Elapid (Cobra, Krait, Mamba) Envenomation

• Neurotoxic pattern: minimal or no local effects initially; systemic neurotoxicity may be delayed 1-12+ hours
• Features: ptosis, ophthalmoplegia, dysarthria, dysphagia, descending flaccid paralysis, respiratory failure
• Some cobras cause significant local necrosis
• Spitting cobras: if venom contacts eye - irrigate copiously with water/saline immediately; topical antibiotics to prevent secondary infection
• Treatment: Antivenom, early endotracheal intubation if any airway compromise, mechanical ventilation (may be needed for days to weeks), neostigmine ± atropine may help with post-synaptic neurotoxins (cobras)
• Coral snakes (US): admit all definite bites; 3-5 vials antivenom IV regardless of symptoms (effects may be irreversible once established); monitor pulmonary function (vital capacity, inspiratory pressure)

Viper Bites Causing Coagulopathy

• Venom-induced consumption coagulopathy (VICC): fibrinogen consumed, PT prolonged
• Do not give FFP, cryoprecipitate, or platelets before antivenom - these are consumed by ongoing venom activity; antivenom is the priority
• After adequate antivenom: clotting usually restores within 6-24 hours

7. Wound Care & Adjunctive Treatment

• Clean the wound with antiseptic; cover with sterile dressing
• Tetanus prophylaxis (toxoid or immunoglobulin as appropriate)
• Antibiotics: Routine prophylaxis is NOT recommended. Give only if there are signs of infection. (A 2025 systematic review [PMID 41287797] noted insufficient evidence to support routine antimicrobial prophylaxis)
• Elevation of bitten limb once antivenom given
• Adequate analgesia (paracetamol/opioids; avoid NSAIDs/aspirin)
• IV fluids for hypovolemia

8. Compartment Syndrome

• Suspected when: severe pain with passive stretch, tense compartment, paresthesia, pallor, pulselessness
• Management: Antivenom is the primary treatment - venom neutralization can reverse compartment pressure
• Mannitol and antivenom together may reduce compartment pressure
• Fasciotomy: only if confirmed compartment pressure >30 mmHg AND antivenom has been given and failed; avoid early fasciotomy as it worsens outcomes in most cases
• Check compartment pressures objectively before considering surgery

9. Special Situations

Renal Failure

• Common with Russell's viper, sea snakes, some African vipers (AKI from VICC, hemolysis, direct tubular toxicity)
• Maintain urine output; dialysis if needed
• A 2026 meta-analysis (PMID 41776424) confirmed snake envenomation is a significant cause of AKI

Sea Snakebites

• Up to 75% are dry bites
• Myotoxicity: rhabdomyolysis, myoglobinuria, hyperkalemia, renal failure
• Neurotoxicity similar to other elapids
• Treat with polyvalent sea snake antivenom or tiger snake antivenom

Pediatric Bites

• Same antivenom dose as adults
• Higher risk of severe envenomation for body weight
• Monitor closely (PMID 41712625 - systematic review on pediatric snakebite in Sub-Saharan Africa)

10. Disposition

11. Things That Are Ineffective/Harmful (Do NOT Do)

• Tourniquet application
• Incision and suction
• Electrocution/electric shock therapy
• Cryotherapy/ice packs
• Pressure immobilization for cytotoxic viper bites
• Routine antibiotics
• Routine fasciotomy before antivenom
• NSAIDs/aspirin (worsen coagulopathy)
• Steroids (no benefit for envenomation; may be used for antivenom reactions)

• Harrison's Principles of Internal Medicine, 22nd ed. (2025), Ch. 471
• Tintinalli's Emergency Medicine, Ch. 212
• Sabiston Textbook of Surgery, 7th ed., Ch. 44
• Mulholland and Greenfield's Surgery, 7th ed.
• Moody S et al., Antimicrobial prophylaxis in snakebite (Systematic Review, 2025) [PMID 41287797]
• Goumboundi IA et al., Snake envenomation and AKI (Meta-analysis, 2026) [PMID 41776424]