Most people think snakebite first aid is settled. Wrap the limb, stretch the bandage until the printed rectangles become squares, keep still, call 000. The last two parts are solid. The rest is less certain than you might think. Two examples show how much is still unresolved: the indicators printed on snakebite bandages, and the disagreement between experts over how the bandage should be applied.
Example one: the rectangle does not measure pressure
We've been told that stretching a bandage until the rectangles become squares gives the correct pressure. It doesn't measure pressure at all. It measures tension. Tension is not pressure, and pressure is not tension.
Tension is how hard the bandage is stretched along its length. That's what the printed shapes show. Pressure is the squeeze the bandage puts on the limb underneath, which is what matters for slowing venom and what can do harm if it's too high.
The two are linked, but the link depends on the limb. Roughly, the pressure under a bandage equals the tension multiplied by the number of layers, divided by the size of the limb. Put the same squares on a large man's thigh and a small woman's forearm, and the forearm gets considerably more pressure. It changes along one limb too: a square at the ankle squeezes harder than one at the thigh, and a square at the wrist harder than one at the upper arm. Wherever turns overlap more, the extra layers add more again.
Time matters as well. Dr David Williams, former head of the Australian Venom Research Unit, has pointed out that common crepe bandages can lose much of their tension within about two hours. So a neat row of squares tells you the bandage was stretched a certain amount when it went on. It does not tell you the pressure on the limb, and it does not tell you the pressure an hour later.
That doesn't make indicators useless. Studies have found that bandages applied in the field are often too loose, and an indicator at least gives a rough idea of how far to stretch. The problem is treating it as a precise gauge of pressure.
Example two: the experts disagree on the details
Even well credentialed experts give different advice on how the bandage should be applied.
Take the sling. Dr David Williams, a recognised snakebite expert now working with the World Health Organization in Geneva, advises against one. His reasoning is that bending a bandaged arm at the elbow can turn the bandage into a tourniquet, so the arm should be splinted straight and gently secured to the body. Australia's official first aid guideline, from ANZCOR, says to use a sling for the arm, as part of keeping the limb still.
ANZCOR is candid about the gaps in its own advice. Its guideline notes that no field studies directly compare first aid techniques in people bitten by snakes. It says it is not clear which part of the technique matters most: the pressure over the bite, the bandage along the whole limb, or the immobilisation. It even notes that bandaging from the fingers upward, the standard method, may push venom along, while bandaging the other way may be too uncomfortable to keep on. And it accepts either two bandages, one over the bite and one up the limb, or a single bandage doing both.
Overseas, Williams favours a firm pad over the bite plus a splint for some bites, rather than bandaging the whole limb. Small studies of that approach in Myanmar have shown promise, but larger studies are still needed.
What both examples tell us
Put the two together and a clear picture emerges. The printed indicator can't tell you the pressure you've achieved, and the experts can't yet agree on exactly what pressure, where, or how. Snakebite first aid is a field still very much in flux.
That is not a reason to skip first aid. It's a reason to understand what the bandage can and can't do, and to put the parts nobody disputes at the centre of everything.
What to do now
Australian guidelines still recommend pressure immobilisation for snakebite. Until that changes, this is what to do:
Call 000 straight away.
Keep the person completely still. Immobilisation is the part of first aid nobody disputes.
Apply a firm, broad bandage over the bite site as soon as possible. It should be firm enough that you can't easily slide a finger between the bandage and the skin.
Apply a second bandage starting at the fingers or toes, extending up to cover as much of the limb as possible.
Treat any indicator on the bandage as a guide, not a guarantee.
Check the fingers or toes beyond the bandage. If they turn pale, blue or cold, the bandage is too tight.
Splint the limb, including the joints either side of the bite. If you use a sling for an arm, avoid bending the elbow sharply, as that can tighten the bandage.
Don't remove the bandage. Leave that to the hospital. The bandage buys time. It is not the treatment.
Sources
ANZCOR Guideline 9.4.8, Envenomation: Pressure Immobilisation Technique
Dr David Williams, First aid for snake bites, WHO webinar, July 2025
For snake removal anywhere in Sydney, call Urban Reptile Removal on 0418 633 474.
