The only two lizards known to be poisonous are the beaded lizard of Mexico and the Gila monster, present in Arizona; Sonora, Mexico; and adjacent areas. The venom of these lizards is somewhat similar in content and effect to that of some pit vipers, although symptoms tend to be much less severe, and bites are almost never fatal. 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. Weakness, sweating, thirst, headache, and ringing in the ears (tinnitus) may develop. In severe cases, blood pressure may fall.

Various suggestions for removing Gila monsters include the following:

• Forcing the jaws open with pliers
• Applying a flame under the lizard's chin
• Immersing the lizard and body extremity under water

Once the lizard has been detached, tooth fragments often remain in the skin and must be removed. Treatment of low blood pressure or blood clotting problems is similar to that of pit viper bites. A specific antivenom is not available.

Last full review/revision February 2009 by Robert A. Barish, MD, MBA