Snakebite, scorpion and envenomation

ASV dosing and adverse reactions

Reviewed Nov 2026·2 references
New· views rounded down, updated weekly

Give 10 vials of polyvalent ASV IV over an hour for systemic envenoming, the same dose for children and pregnant women, with no test dose and adrenaline drawn up. Repeat by the 6-hour rule (haemotoxic) or 1-2-hour rule (neurotoxic), and manage reactions by pausing, adrenaline IM and restarting.

At the bedside

Timed steps
  1. 1

    Systemic envenoming

    Indication

    Incoagulable 20WBCT, spontaneous bleeding, neurotoxicity, shock, AKI, rhabdomyolysis, or local swelling > half the limb / rapidly progressive.

  2. 2

    Safety first

    Prepare

    Adrenaline 0.5 mg drawn up, resuscitation trolley; no test dose; no prophylactic premedication requirement.

  3. 3

    Loading

    Give

    10 vials in ~200 mL NS over 1 h (same in children and pregnancy).

  4. 4

    Rules

    Repeat

    Haemotoxic: 20WBCT at 6 h, repeat 10 vials if non-clotting, or if bleeding persists 1 h after the first dose. Neurotoxic: repeat 10 vials if no improvement 1-2 h after the first dose.

  5. 5

    Manage

    Reaction

    Stop infusion; adrenaline 0.5 mg IM (0.01 mg/kg child); antihistamine and hydrocortisone as adjuncts; restart ASV slowly once settled.

  6. 6

    Serum sickness

    Later

    Fever, arthralgia, rash 5-24 days later: antihistamine, prednisolone short course.

Systemic envenoming (adult or child)

Anti-snake venom (polyvalent ASV)

IV infusion
Dose
10 vials over 1 h; repeat 10 vials per rules
Worked example
A 22 kg child with incoagulable 20WBCT receives 10 vials, not a weight-based reduced dose.

Usual maximum: haemotoxic 25-30 vials, neurotoxic 20 vials (MoHFW STG).

ASV reaction / anaphylaxis

Adrenaline (epinephrine)

IM anterolateral thigh
Dose
0.5 mg (0.01 mg/kg in children, max 0.5 mg); repeat every 5-15 min
Range
0.3–0.5 mg
Worked example
22 kg child: 0.22 mg = 0.22 mL of 1 mg/mL.
Red flag · call your senior now
Hypotension, stridor or bronchospasm during ASV: anaphylaxis – adrenaline IM now.
Pitfall
Giving an intradermal test dose – delays treatment and does not predict reactions.
Pitfall
Continuing ASV beyond maximum in hump-nosed pit viper or non-Big Four bites.
Pearl
ASV cannot reverse established tissue damage (AKI, necrosis); treat early and support organs.

References

  1. 1

    Directorate General of Health Services, Ministry of Health and Family Welfare, Government of India. Standard Treatment Guidelines: Snakebite. New Delhi: MoHFW/NHSRC; June 2016

  2. 2

    World Health Organization Regional Office for South-East Asia. Guidelines for the management of snakebites. 2nd ed. New Delhi: WHO SEARO; 2016

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Educational reference for trained clinicians. Check doses against your hospital protocol and the patient in front of you.