It and the other members of the same genus, including the Gila monster (Heloderma suspectum), are the only lizards known to have evolved an overt venom delivery system.

The Mexican beaded lizard is larger than the Gila monster, with duller coloration, black with yellowish bands.

Maximum weight known is 4,000 g (8.8 lb)[9][10] Although males are slightly larger than females, the beaded lizards are not sexually dimorphic.

The Chiapan beaded lizard (H. alvarezi) is found in northern Chiapas and the depression of the Río Lagartero in Huehuetenango to northwestern Guatemala.

[13] The Guatemalan beaded lizard (H. charlesbogerti) is the only allopatric one, separated from the nearest population (H. alvarezi) by 250 km of unsuitable habitat.

[12] The beaded lizard is a specialized vertebrate nest predator, feeding primarily on bird and reptile eggs.

It consists of a number of components, including L-amino acid oxidase, hyaluronidase, phospholipase A, serotonin, and highly active kallikreins that release vasoactive kinins.

Almost all documented human bites (eight in the past century) have resulted from prodding captive lizards with a finger or bare foot.

In mammals such as rats, major effects include a rapid reduction in carotid blood flow followed by a marked fall in blood pressure, respiratory irregularities, tachycardia, and other cardiac anomalies, as well as hypothermia, edema, and internal hemorrhage in the gastrointestinal tract, lungs, eyes, liver, and kidneys.

Other common effects of bites on humans include local edema (swelling), weakness, sweating, and a rapid fall in blood pressure.

[17] Some compounds in its venom have been shown to have pharmacological properties relating to the possible treatment of diabetes, Alzheimer's disease, and even HIV.

[20] The beaded lizard becomes sexually mature as early as 3 years, and typically mates during summer months.

They are believed to spend much of their early lives underground, emerging at 2–3 years of age after gaining considerable size.

It is incorrectly believed, for example, to be more venomous than a rattlesnake, can cause lightning strikes with its tail, or make a pregnant woman miscarry by merely looking at her.