An adder coiled up on mossy ground — The adder, *Vipera berus*, is the UK’s only venomous snake. © Miroslav Hlavko/ Shutterstock

British snakes: Are there dangerous reptiles in the UK?

By Emily Osterloff

First published 23 August 2018Last updated 27 February 2024

During the summer months, snakebites are more often reported across Britain. But are our native reptiles really more volatile when temperatures warm up?

There are very few dangerous animals living in and around Britain. Although the sight of a snake might be terrifying to some, the species found in the wild in the UK are rarely cause for concern.

Get to know the snake species you might spot out and about in Britain and how to work out what you’ve seen.

Types of snakes in the UK and how to identify them

There are four species of snake living in the wild in Britain. Three are native and one is a non-native, introduced species.

Common European adder

An adder curled up in a pile of dead bracken. Its zig-zag markings are visible down the length of the body. — Adders have a distinctive zigzag pattern running down the full length of their backs. © Jamie Hall/ Shutterstock

The common European adder, also known as the common European viper, is Britain’s only venomous snake. In the UK, it’s often just referred to as the adder and is found across England, Scotland and Wales. They’re mainly found in heathlands, commons and woodland.

Adders have stocky bodies, reaching a maximum length of approximately one metre. They vary in colour: males are usually grey and female adders are often reddish, although there are some that are entirely black, which is what’s known as a melanistic form.

They have a distinctive, darker zigzag pattern down the middle of their backs and a clear V or X marking on the top of the head. These snakes have a slit pupil - similar to a cat’s - instead of a round one. They also have keeled scales - rather than being smooth, they have a raised ridge down their centre.

Barred grass snakes

A barred grass snake resting on leaves in a pond — Grass snakes are the largest snakes native to Britain. © Dr.Pixel/ Shutterstock

Barred grass snakes, Natrix helvetica, are the largest snakes native to Britain. They generally reach approximately 1.3 metres long.

These snakes are green with dark bars and they have a black and cream or white collar at the base of the head. Their eyes have a round pupil.

Grass snakes are proficient swimmers and feed mostly on amphibians. You will find these snakes across England and Wales, often in or near water, but also in grasslands and gardens.

Smooth snakes

A smooth snake on the ground, wrapped around a small plant. — The smooth snake has polished scales and a round pupil with a golden iris. It has less distinctive markings on its back than the adder. © Martin Pelanek/ Shutterstock

Smooth snakes, Coronella austriaca, are very rarely encountered. In the UK they’re only found in the heathlands of Dorset, Surrey and Hampshire.

These snakes are up to about 70 centimetres long. The colour of their scales makes them look a bit like the adder. But you can tell these two apart, as the pattern on the smooth snake’s back is not as distinctly zigzagged as the adder's. Additionally, smooth snakes have polished - unkeeled - scales and a round pupil with a golden iris.

Smooth snakes are also found across continental Europe and into Asia, from northern Spain to Iran.

British snakes: Are there dangerous reptiles in the UK?

Types of snakes in the UK and how to identify them

Common European adder

Barred grass snakes

Smooth snakes

Aesculapian snakes