It's the UK's only venomous snake – but how likely are you to be bitten by one and are they really that deadly?

The adder is the UK’s only venomous snake and its numbers have declined dramatically over the past 50 years.

Today, it is largely restricted to dunes, heathland, woodland edges and coastal paths where most human encounters occur. For instance, in July 2024, two people were bitten at Braunton Burrows Nature Reserve in Devon.

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How common are adder bites?

There are probably more scare stories published about adders each year than actual adder bites (some 50–100 bites, according to Amphibian and Reptile Conservation, with an additional 100 bites of dogs).

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Adders only bite people if threatened, such as when handled or trodden on; they are small, cryptically coloured and easily overlooked. If bitten, seek immediate medical help, as the bites, though potentially serious, are easily treated. And in 70% of cases, there’s virtually no reaction beyond stinging and a rash. The last confirmed death from an adder bite was in 1975; there have been 14 deaths since 1876.

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