The Gila monster is one of only a handful of venomous lizards in the world. Others include the similar-looking Mexican beaded lizards, as well as iguanas and monitor lizards. Its venom is a fairly mild neurotoxin. And though a Gila bite is extremely painful, none has resulted in a reported human death.
It has been accused of many things, such as spitting venom, leaping several feet in the air to attack, stinging with its tongue, and killing people with gusts of poisonous breath. ... It may even chew so that the venom goes deeper into the wound. A Gila monster bite is painful to humans, but it rarely causes death.
Powerful muscles control the jaws and give the Gila Monster a bite like a bulldog--it just won't let go. This gives the venom a chance to work, weakening or disabling the lizard's prey.