A female adder (vipera berus) basking during March 2010. She had not long emerged from hibernation and was a little sluggish as it was still pretty cold.
The adder is Britain's only venomous snake, but their venom is not that potent. However, if you are bitten you should treat it as an emergency, as an allergic reaction to the venom can cause anaphylactic shock. If this goes untreated it can prove fatal.
Young children and old people are more vulnerable to the adders venom. And don't forget dogs - If your dog is bitten, get it to the vet asap!
The adder will only release venom if hunting for food, or if it feels its life is in danger. They sometimes give a warning bite and this is called a dry bite, where they bite, but don't release venom.
It takes a lot of the snakes energy to produce venom, venom that they rely on for catching their prey.