Unlike most snakes, the Gila monster and beaded lizard clamp on firmly when they bite and chew the venom into the person rather than injecting it through fangs. The lizard may be difficult to dislodge. Common symptoms include pain, swelling, and discoloration in the area around the bite as well as swollen lymph nodes.

Toxicity. The venom of a Gila monster is normally not fatal to healthy adult humans. One fatality has been confirmed since 1930, on February 12th, 2024, and the rare fatalities recorded before 1930 occurred in adults who were intoxicated by alcohol or had mismanaged the treatment of the bite.

The Gila monster's bite may be agonising, but humans have been using the lizard's venom to save lives. Over 30 years ago scientists discovered the potential of Gila monster venom as a treatment for type 2 diabetes.

When biting, the beaded lizard hangs on its victim and chews to get its venomous saliva into the wound. Although its jaw grip is strong, its unsocketed teeth are easily broken off at their bases. The beaded lizard's venom is a weak hemotoxin, and although human deaths are rare, it can cause respiratory failure.