First aid and what to undo, the clinical syndrome, the clotting test, and whether antivenom is indicated. Follows the WHO guideline step by step.
Antivenom is not dosed by body weight. Snakes inject the same dose of venom into children and adults. Children must therefore be given exactly the same dose of antivenom as adults.
Decision-support only. This tool reproduces the WHO SEARO Guidelines for the Management of Snakebites, 2nd edition (2016) so you can apply them quickly. It does not replace clinical judgement, your hospital protocol, or the guideline itself. It deliberately does not print antivenom vial counts — see step 5 for why.
✓ Clinically reviewed by Dr Syed Usama Hussain, MBBS, BSc · 05 Aug 2026.
Step 1 · First aid — and what to undo
WHO SEARO 2016 §6.2–6.3
Do this
✓
Reassure the victim
Reassurance slows the heart rate and reduces the spread of venom. Grounds for reassurance: a bite by a venomous snake may still be a "dry bite", severe envenoming usually evolves slowly, and modern management is effective.
✓
Immobilise the whole patient, not just the limb
Lay them down in the recovery position and splint or sling the bitten limb. "Any movement or muscular contraction, even undressing or walking, will increase absorption and spread of venom by squeezing veins and lymphatics."
✓
Apply pressure-pad immobilisation unless an elapid bite can confidently be excluded
WHO: apply pressure-pad immobilisation, or pressure-bandage immobilisation if the equipment and skills are available. The pressure-pad method is "preferred and recommended as being simpler and more practicable". It reduced venom spread in Russell's viper bite victims in Myanmar.
✓
Remove rings, bangles and anything constricting
Before swelling makes removal impossible.
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Transport quickly, but safely and comfortably
Minimise movement of the bitten limb in transit. Keep the patient in the recovery position in case they vomit.
✓
Photograph the snake — do not chase or kill it
"Do not attempt to kill it as this may be dangerous." If it is already dead, bring it — but never handle it with bare hands, "as even a severed head can bite!"
Never do this
MOST TRADITIONAL FIRST-AID METHODS SHOULD BE DISCOURAGED: THEY DO MORE HARM THAN GOOD!
✕Tight (arterial) tourniquets — "must never be recommended or condoned!" Many gangrenous limbs have resulted.
✕Incisions, or any interference with the bite wound
✕Rubbing, massage or vigorous cleaning of the wound
✕Suction — by mouth, device or "snake stone"
✕Application of herbs or chemicals
✕Ice, electric shock, and cautery
The patient arrives with a tight band already tied. Do not just cut it off.
CAUTION Delay the release of tight bands, bandages and ligatures: if the patient has already applied these very popular methods of first-aid, they should not be released until the patient is under medical care in hospital, medical staff and resuscitation facilities are available and antivenom treatment has been started.
WHO lists "sudden deterioration, or rapid development of severe systemic envenoming after releasing a tight tourniquet or compression bandage" among the clinical situations requiring urgent resuscitation. Releasing the band delivers a bolus of pooled venom into the circulation.
In practice: Secure IV access, have adrenaline drawn up, start antivenom if indicated — and only then release the band, with resuscitation facilities to hand.
Step 2 · Resuscitate first, diagnose second
WHO SEARO 2016 §6.4
ABCDE: Airway · Breathing · Circulation · Disability (level of consciousness) · Exposure and environmental control. Check airway patency, respiratory movements, arterial pulse and level of consciousness immediately, and record the vital signs.
Do not use the Glasgow Coma Scale on a paralysed patient. The Glasgow Coma Scale cannot be used to assess the level of consciousness of patients paralysed by neurotoxic venoms. A fully conscious patient with complete paralysis can score as deeply comatose.
Tick any that apply — these need urgent resuscitation now
Early systemic envenoming is easy to dismiss
A common early symptom of systemic envenoming is vomiting and, after bites by some species, fainting and collapsing (sometimes causing injury) with transient unconsciousness and features of anaphylaxis such as angioedema.
Local signs to look for and record
Fang marks
Persistent local bleeding from the fang marks
Spreading local swelling
Lymphangitis and tender enlargement of the draining lymph node
Inflammation — swelling, redness, heat
Blistering
Local infection, abscess formation
Necrosis
No signs yet is not a discharge criterion. A "dry bite" is common even when the snake was venomous. Absence of envenoming at presentation is not a discharge criterion — the emerging clinical syndrome is what matters, so observe.
Step 3 · Which syndrome — not which photograph
WHO SEARO 2016 §5.3, §6.5
Do not identify the snake from a photo and treat on that. Identifying a dead snake "requires skill and even experienced medical personnel may mistake harmless mimics for venomous snakes, or they may confuse different venomous species. As a result, the patient may be given antivenom unnecessarily." Do not let a photograph override the clinical syndrome.
Syndrome 1 · Local envenoming (swelling etc.) with bleeding/clotting disturbances
→ Viperidae — all species
Syndrome 2 · Local envenoming with bleeding/clotting disturbances, shock or acute kidney injury
→ Russell's viper. Conjunctival oedema (chemosis) and acute pituitary insufficiency, or ptosis, external ophthalmoplegia and facial paralysis with dark brown urine, are described in Russell's viper envenoming in parts of the region.
Syndrome 3 · Local envenoming (swelling etc.) with paralysis
→ Cobra or king cobra
Syndrome 4 · Paralysis with minimal or no local envenoming
→ Bitten on land while sleeping on the ground, with or without abdominal pain = krait. Bitten in the sea, an estuary or some freshwater lakes = sea snake.
Syndrome 5 · Paralysis with dark brown urine and acute kidney injury
→ Bitten on land with bleeding/clotting disturbance = Russell's viper. Bitten on land while sleeping indoors = krait. Bitten in the sea, an estuary or some freshwater lakes, with no bleeding/clotting disturbance = sea snake.
Limitations of the syndromic approach: "The more carefully the clinical effects of snakebites are studied, the more it is realised that the range of activities of a particular venom is very wide." There is considerable overlap between species. The syndromic approach is useful when the snake has not been identified — it is not a species diagnosis.
Which species these are in Pakistan
Group
Species encountered in Pakistan
Cobra
Naja naja (black/spectacled cobra) throughout; Naja oxiana (Oxus or Central Asian cobra) in the north and north-west
The bite with nothing to see. The krait bite that kills is the one with nothing to see: bitten while sleeping on the ground, minimal or no local signs, abdominal pain, then progressive paralysis. Syndrome 4 exists precisely because there is no swelling to prompt the diagnosis.
Step 4 · The 20-minute whole blood clotting test
WHO SEARO 2016 §6.6
1
Place 2 ml of freshly sampled venous blood in a small, new, dry, ordinary glass vessel
2
Leave undisturbed for 20 minutes at ambient temperature
3
Tip the vessel once
4
If the blood is still liquid (unclotted) and runs out, the patient has hypofibrinogenaemia ("incoagulable blood") from venom-induced consumption coagulopathy
What a positive test means. In the South-East Asia Region, incoagulable blood is diagnostic of a viper bite and rules out an elapid bite.
It must be ordinary glass. If the vessel used for the test is not made of ordinary glass, or if it has been cleaned with detergent, its wall may not stimulate clotting of the blood sample (surface activation of factor XII — Hageman factor) and the test will be invalid.
False positives. A "false positive" (non-clotting) result comes from using plastic, polystyrene or polypropylene, or a glass vessel that has been cleaned with detergent, soap or washing fluid, or is wet or contaminated, or a glass syringe with an anticoagulant lubricant.
False negatives. A "false negative" (clotting) result occurs with milder coagulopathy. The 20WBCT is less sensitive than PT, aPTT or fibrinogen assay in the early stages of evolving venom-induced DIC. It becomes positive at plasma fibrinogen below 0.5 g/L.
If glass tubes are hard to get. Recycled glass antibiotic bottles can be made suitable, provided they are washed with normal 0.9% saline only — no detergent or other cleansing agent — followed by hot air drying.
Do not substitute a variant. Variants such as the 30-minute WBCT, the "2,3,5 syringe test" and the capillary tube test "have not been standardised or validated" and carry the same risk of false positives.
WHO's recommendation, in full
In the absence of an alternative simple bed-side test of blood coagulability available in hospitals in the developing world, the 20WBCT should continue to be used. However, every effort should be made to eliminate false positive (non-clotting) results by ensuring that ordinary glass is used, that recycled glass vessels are not cleaned with detergents or other cleansing fluids and that a normal control blood is used for comparison in cases where the 20WBCT result is inconsistent with the patient's clinical condition. Accepting that the 20WBCT may remain negative (clotting) in patients with evolving venom-induced DIC, the test should be repeated frequently and antivenom treatment should not be delayed if there is other evidence of anti-haemostatic disturbances (e.g. spontaneous systemic bleeding distant from the bite site).
Everything else worth sending
Test
Why
Prothrombin time (PT/INR), aPTT, fibrinogen
More sensitive than the 20WBCT and detect evolving coagulopathy earlier.
Platelet count
Thrombocytopenia below 100 × 10⁹/L is itself an indication for antivenom.
Haematocrit
A transient increase indicates haemoconcentration from generalised capillary leak (Russell's viper). A decrease reflects blood loss.
Creatinine and urea
Acute kidney injury is an indication for antivenom and may require renal replacement therapy.
Creatine kinase, urine dipstick for blood
Rhabdomyolysis and haemoglobinuria/myoglobinuria — dark brown urine. Alkaline diuresis is continued until CK falls below 5000 U.
ECG and potassium
Cardiac arrest can be precipitated by hyperkalaemia from rhabdomyolysis after bites by sea snakes, certain kraits and Russell's vipers.
Step 5 · Is antivenom indicated?
WHO SEARO 2016 §6.7
Antivenom is the only specific antidote to snake venom. A most important decision in the management of a snakebite victim is whether or not to give antivenom.
Antivenom should be given only to patients in whom its benefits are considered likely to exceed its risks. Since antivenom is relatively costly and often in limited supply, it should not be used indiscriminately. The risk of reactions should always be taken into consideration.
Systemic envenoming — tick any that apply
Local envenoming — tick any that apply
Dose
Children get the adult dose. Snakes inject the same dose of venom into children and adults. Children must therefore be given exactly the same dose of antivenom as adults.
Repeat dose. If the blood remains incoagulable (as measured by 20WBCT) six hours after the initial dose of antivenom, the same dose should be repeated. This is based on the observation that, if a large dose of antivenom (more than enough to neutralize the venom procoagulant enzymes) is given initially, the time taken for the liver to restore coagulable levels of fibrinogen and other clotting factors is 3–9 hours.
Why this tool gives no vial count. No vial count is given here. WHO states initial doses per manufacturer in Annex 3, and its own entry for the National Institute of Health, Biological Production Division, Islamabad reads "(no recent information available)". Read the neutralising capacity printed on the product you are actually holding, and follow your hospital protocol.
Giving it
Adrenaline (epinephrine) should always be available at the bed-side, ideally drawn up in readiness, before antivenom is administered.
Antivenom is given by the intravenous route — diluted in about 5 ml per kg body weight of isotonic saline or 5% dextrose (roughly 250 ml in an adult) and infused at a constant rate over about 30–60 minutes.
Patients must be closely observed for at least one hour after starting intravenous antivenom administration, so that early anaphylactic antivenom reactions can be detected and treated early.
Reactions
A substantial proportion of patients develop reactions, either early (within a few hours) or late (5 days or more). In Sri Lanka, Indian polyvalent antivenoms caused reactions in as many as 81% of recipients and severe reactions in as many as 43%. In India, reported reaction rates range from 5.6% to 56%, of which 10–15% are moderate to severe.
Adrenaline (epinephrine) intramuscularly, ideally into the upper lateral thigh — 0.5 mg for adults, 0.01 mg/kg body weight for children.
Give it at the very first sign of a reaction — "even when only a few spots of urticaria have appeared or at the start of itching, tachycardia or restlessness" — because severe anaphylaxis can evolve very rapidly.
Then chlorphenamine maleate (adults 10 mg, children 0.2 mg/kg IV over a few minutes). Hydrocortisone (adults 100 mg, children 2 mg/kg) may be given but is unlikely to act for several hours.
Unresponsive anaphylaxis: lie supine with legs elevated, 1–2 litres of 0.9% saline rapidly in an adult, then consider an adrenaline infusion and a vasopressor.
Premedication does not work. Histamine anti-H1 and anti-H2 blockers, corticosteroids, and the rate of intravenous infusion of antivenom (between 10 and 120 minutes) do not affect the incidence or severity of early antivenom reactions. Corticosteroids do not reduce the risk of biphasic anaphylaxis.
Giving it when it is not indicated
In some parts of the world, a small standard dose of antivenom is given routinely to any patient claiming to have been bitten by a snake, irrespective of symptoms or signs of envenoming. Sometimes the local community are so frightened of snakebite that they compel the doctor to give antivenom against medical judgement.
Step 6 · Neurotoxicity, the limb, and discharge
WHO SEARO 2016 §6.9–6.13
Trial of anticholinesterase in every neurotoxic patient
A trial of anticholinesterase should be performed in every patient with neurotoxic envenoming, as it would be in any patient with suspected myasthenia gravis. However, this should not delay antivenom treatment or endotracheal intubation. Patients must be observed closely as they may deteriorate while the trial of anticholinesterase is being carried out.
1
Make baseline observations against which to assess the effect — ptosis is measured as the distance between the upper and lower lid margins with a millimetre ruler; ventilatory capacity as peak flow, FEV1 or maximum expiratory pressure.
2
Give atropine sulphate intravenously — 0.6 mg for adults, 50 µg/kg for children — or glycopyrronium.
3
Then give neostigmine bromide or methylsulphate intramuscularly — 0.02 mg/kg for adults, 0.04 mg/kg for children. Edrophonium (Tensilon) 10 mg for adults or 0.25 mg/kg for children is ideal but is rarely available in the region.
4
Observe over the next 30–60 minutes for neostigmine, or 10–20 minutes for edrophonium. Ptosis may disappear and ventilatory capacity may improve.
5
Patients who respond convincingly can be maintained on neostigmine methylsulphate 0.5–2.5 mg every 1–3 hours, up to 10 mg per 24 hours in adults, or 0.01–0.04 mg/kg every 2–4 hours in children, together with atropine to block muscarinic side effects.
Ventilation. Assisted ventilation may be needed for prolonged periods. Manual ventilation with an anaesthetic bag, by relays of doctors, medical students, relatives and nurses, has been effective where no mechanical ventilator was available.
The bitten limb
Leave the wound alone. Surgical débridement is for frankly necrotic tissue. Tetanus toxoid booster and prompt antibiotic treatment of necrotic wounds is recommended.
Not into an incoagulable patient. Haemostatic abnormalities — strict bed rest to avoid even minor trauma including intramuscular injections. Give the tetanus toxoid once coagulopathy has been corrected, not before.
Compartment syndrome and fasciotomy
Clinical features:
Disproportionately severe pain
Weakness of intracompartmental muscles
Pain on passive stretching of intracompartmental muscles
Hypoaesthesia of areas of skin supplied by nerves running through the compartment
Obvious tenseness of the compartment on palpation
The classical signs are difficult to assess in snake-bitten limbs and "many unnecessary, dangerous and debilitating fasciotomies are performed, especially where surgeons rather than physicians have the primary responsibility for managing snakebite cases". Palpable or Doppler-detectable arterial pulses do not exclude intracompartmental ischaemia.
All three criteria must be met before fasciotomy:
Haemostatic abnormalities have been corrected — antivenom with or without clotting factors
Clinical evidence of an intracompartmental syndrome
Intracompartmental pressure above 40 mmHg in adults, measured directly
Direct measurement of intracompartmental pressure is mandatory and fasciotomy must not be attempted before haemostatic disturbances have been corrected by antivenom. Early treatment with antivenom remains the best way of preventing irreversible muscle damage.
Before discharge
Most patients can be assured of a full recovery in time.
Encourage rehabilitation exercises until normal function is restored to the bitten limb — "conventional physiotherapy accelerates functional recovery of the bitten limb, but is often forgotten".
Arrange follow-up after 1–2 weeks to check progress and give further reassurance.
Warn about late serum sickness-type reactions 5 days or more after antivenom, and reassure them that this complication can be treated.
Give advice on reducing the risk of further bites, ideally as a leaflet to share with family and neighbours.
Four things worth carrying with you
A "dry bite" is common even when the snake was venomous. Absence of envenoming at presentation is not a discharge criterion — the emerging clinical syndrome is what matters, so observe.
The krait bite that kills is the one with nothing to see: bitten while sleeping on the ground, minimal or no local signs, abdominal pain, then progressive paralysis. Syndrome 4 exists precisely because there is no swelling to prompt the diagnosis.
Do not use the Glasgow Coma Scale on a paralysed patient. A fully alert person with complete neurotoxic paralysis can be scored as deeply comatose and managed as if unconscious.
Antivenom is the treatment for coagulopathy. Fresh frozen plasma and platelets do not substitute for it, and fasciotomy before the coagulopathy is corrected causes catastrophic bleeding.
Common questions
Do children need a smaller dose of antivenom?
No. WHO states it plainly: snakes inject the same dose of venom into children and adults, so children must be given exactly the same dose of antivenom as adults. Scaling antivenom by body weight under-doses a child and is one of the most dangerous errors in snakebite care.
The patient arrives with a tight tourniquet already tied. Should I remove it?
Not immediately. WHO cautions that tight bands, bandages and ligatures should not be released until the patient is under medical care in hospital, medical staff and resuscitation facilities are available, and antivenom treatment has been started. Sudden deterioration after releasing a tourniquet is listed among the situations requiring urgent resuscitation.
When is antivenom indicated?
When there is systemic envenoming — haemostatic abnormality (spontaneous systemic bleeding, non-clotting 20WBCT, INR above 1.2, or platelets under 100 000), neurotoxicity, cardiovascular abnormality, acute kidney injury, or haemoglobinuria/myoglobinuria. Or significant local envenoming — swelling involving more than half the limb within 48 hours, swelling after a bite on a digit, rapid extension of swelling, or an enlarged tender draining lymph node.
How do I do the 20-minute whole blood clotting test?
Place 2 ml of fresh venous blood in a small, new, dry, ordinary glass vessel. Leave it undisturbed for 20 minutes at ambient temperature, then tip it once. If the blood is still liquid and runs out, the patient has incoagulable blood from venom-induced consumption coagulopathy. Plastic tubes, or glass washed with detergent, invalidate the test.
A patient was bitten while sleeping and has no swelling at all. Can it still be envenoming?
Yes, and this is the presentation that gets missed. Paralysis with minimal or no local envenoming after being bitten on land while sleeping on the ground, with or without abdominal pain, is WHO Syndrome 4 and points to a krait. There is nothing to see at the bite site, so the diagnosis depends on recognising the syndrome.
When should fasciotomy be done for a swollen snake-bitten limb?
Rarely, and never early. WHO requires all three: haemostatic abnormalities corrected with antivenom, clinical evidence of a compartment syndrome, and a directly measured intracompartmental pressure above 40 mmHg in adults. Direct measurement is mandatory, and fasciotomy before the coagulopathy is corrected causes catastrophic bleeding.
Can I use the Glasgow Coma Scale on a snakebite patient?
Not on a paralysed one. WHO states the GCS cannot be used to assess the level of consciousness of patients paralysed by neurotoxic venoms. A fully alert patient with complete neurotoxic paralysis can be scored as deeply comatose.
How much antivenom should I give?
This tool deliberately does not print a vial count. WHO states initial doses per manufacturer, Pakistan uses a mix of NIH Islamabad, Indian and Saudi products, and WHO's own record for the Pakistani producer reads "no recent information available". Read the neutralising capacity printed on the product you are holding and follow your hospital protocol. The rules that do not vary: the same dose for children as adults, and repeat the same dose if blood is still incoagulable six hours later.
Clinically reviewed by Dr Syed Usama Hussain, MBBS, BSc
MBBS, BSc — active medical practitioner in Pakistan. Graduated from Federal Medical & Dental College, Islamabad (2021) and completed a one-year clinical internship at the Pakistan Institute of Medical Sciences (PIMS), Islamabad (2022).
Sources
World Health Organization, Regional Office for South-East Asia. Guidelines for the Management of Snakebites, 2nd edition. New Delhi: WHO; 2016. ISBN 978-92-9022-530-0.
WHO SEARO 2016, Foreword — scope: "Countries such as Malaysia, Singapore, Cambodia, Lao People's Democratic Republic, Republic of Korea, Philippines, Pakistan and Afghanistan may share many of the same medically-important species of snakes that occur in the South-East Asia Region and may find these guidelines useful."
Species commonly encountered in Pakistan (Naja naja, N. oxiana, Bungarus caeruleus, Daboia russelii, Echis carinatus) are drawn from the Pakistani venomics literature, not from the WHO species chapter, which is organised by SEARO country.
Background reading — why the tourniquet stays on until antivenom is running, the krait bite that leaves nothing to see, and how the clotting test fails: snake bite in Pakistan.