🚑 EmergencyToxicology / EmergencyStudentInternResident

Snakebite Envenomation

Also known as: snake bite · ASV · envenoming

A medical emergency from a venomous snakebite. In India the “Big Four” (cobra, krait, Russell's viper, saw-scaled viper) cause neurotoxic and/or haemotoxic envenomation. Polyvalent anti-snake venom (ASV) is the antidote; many bites are “dry”.

Source · Reviewed 2026-08-15 · v1.0— AI-assisted draft — confirm ASV dosing against the current National/ICMR snakebite protocol before clinical use.

⚕️ Education only — not medical advice. Verify against the latest official guideline and your local protocol; confirm every drug dose against the cited source before clinical use.

Who gets it

Rural and agricultural communities, especially in the monsoon and when sleeping on the floor outdoors; bites are often on the limbs.

Red flags — escalate / refer

Signs of SYSTEMIC envenomation → give ASV: neuroparalysis (ptosis, ophthalmoplegia, bulbar/respiratory weakness), OR coagulopathy/bleeding with a non-clotting 20-minute WBCT, OR shock/severe local necrosis.
Respiratory muscle paralysis → intubate and ventilate.
Russell's viper bites can cause acute kidney injury and capillary leak — monitor urine output and renal function.

Work-up / diagnosis

1Keep the patient calm and still; look for systemic envenomation clinically.
220-minute Whole Blood Clotting Test (20WBCT): 2 mL fresh venous blood in a clean, dry glass tube left undisturbed for 20 minutes — non-clotting means coagulopathy (haemotoxic envenomation) and is an indication for ASV. Repeat 6-hourly to guide re-dosing.
3Monitor neurological signs, urine output and renal function; keep adrenaline ready for ASV anaphylaxis.

Management — overview

First aid: reassure; immobilise the bitten limb with a splint (as for a fracture) at about heart level; remove rings/tight items; transport to hospital urgently. Do NOT cut, suck, apply a tight tourniquet, or use herbal remedies.
Give polyvalent ASV ONLY for systemic envenomation (positive 20WBCT, neurotoxicity, or significant progression) — not for every bite.
Neurotoxic envenomation: trial neostigmine with atropine; be ready to support the airway and ventilate.
Supportive care: paracetamol for pain (not NSAIDs/aspirin), tetanus prophylaxis, wound care; treat AKI (dialysis if needed).
Keep adrenaline drawn up to treat ASV anaphylaxis.

In-depthFull dosing & advanced protocol

Drug dosing

Polyvalent Anti-Snake Venom (ASV)

Systemic envenomation only

Adult dose: Initial 8–10 vials, reconstituted and given IV over ~1 h in isotonic fluid; repeat per 20WBCT (6-hourly) or worsening neurotoxicity
Paediatric: SAME dose as adults — the venom load is identical
Route: Intravenous infusion

Caution: Keep adrenaline ready for anaphylaxis. Confirm the dose and schedule against the current National/ICMR snakebite protocol.

ICMRStandard Treatment Workflows (STWs), India — Dept. of Health Research & ICMR (2022+) ↗

Neostigmine + Atropine (neurotoxic bites)

Neuroparalysis (esp. cobra)

Adult dose: Neostigmine 0.5 mg IV with atropine 0.6 mg IV; reassess response
Paediatric: Neostigmine 0.04 mg/kg with atropine 0.05 mg/kg
Route: Intravenous

ICMRStandard Treatment Workflows (STWs), India — Dept. of Health Research & ICMR (2022+) ↗

Adrenaline 1 mg/mL (1:1000)

Ready for ASV anaphylaxis

Adult dose: 0.5 mg IM if a reaction occurs
Route: Intramuscular

WHOWHO Model List of Essential Medicines (electronic EML) (2025 (24th)) ↗

Species patterns & complications

Krait: nocturnal, often a painless bite with delayed descending paralysis and abdominal pain; little local swelling.
Russell's viper: coagulopathy plus acute kidney injury and capillary-leak — monitor renal function and consider dialysis.
Cobra: prominent local necrosis plus neurotoxicity.

WHOWHO SEARO — Guidelines for the management of snakebites ↗

Ventilation & ASV reactions

Bulbar/respiratory paralysis: intubate and ventilate; recovery follows as venom is neutralised/cleared.
ASV anaphylaxis: pause the infusion, give IM adrenaline, then cautiously resume once stable.

WHOWHO SEARO — Guidelines for the management of snakebites ↗

References

Guidelines change. If something here is out of date, tell us — we keep these current.

🚩 Report outdated / suggest update

More protocols

AnaphylaxisAcute, life-threatening systemic hypersensitivity with airway, breathing or circulation compromise within minutes of a trigger. Intramuscular adrenaline is the immediate, life-saving treatment.Sepsis & Septic ShockLife-threatening organ dysfunction from a dysregulated host response to infection. Early recognition and the “hour-1 bundle” save lives; septic shock adds fluid-refractory hypotension.Animal Bite & Rabies ProphylaxisRabies is almost 100% fatal once symptomatic but almost 100% preventable with correct post-exposure prophylaxis (PEP). Treat every mammal bite as an emergency for wound care and risk assessment.

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👤 Who gets it

🚩 Red flags — escalate / refer

🔎 Work-up / diagnosis

🧭 Management — overview

💊 Drug dosing

Polyvalent Anti-Snake Venom (ASV)

Neostigmine + Atropine (neurotoxic bites)

Adrenaline 1 mg/mL (1:1000)

📈 Species patterns & complications

📈 Ventilation & ASV reactions

📚 References

More protocols

👤 Who gets it

🚩 Red flags — escalate / refer

🔎 Work-up / diagnosis

🧭 Management — overview

💊 Drug dosing

Polyvalent Anti-Snake Venom (ASV)

Neostigmine + Atropine (neurotoxic bites)

Adrenaline 1 mg/mL (1:1000)

📈 Species patterns & complications

📈 Ventilation & ASV reactions

📚 References

More protocols

Who gets it

Red flags — escalate / refer

Work-up / diagnosis

Management — overview

Drug dosing

Species patterns & complications

Ventilation & ASV reactions

References

Who gets it

Red flags — escalate / refer

Work-up / diagnosis

Management — overview

Drug dosing

Species patterns & complications

Ventilation & ASV reactions

References