Emergency Medicine

More Rain, More Rattlers: Colorado’s Venomous Summer Begins

Written by Greg Glasgow | June 19, 2025

 

A wet and rainy spring — like the one Colorado is nearing the end of — is great for lawns and parks, but it also means an increase in snakebites, research from the University of Colorado Boulder found, likely due to an increase in the numbers of prey animals like mice and other rodents.

Colorado is home to three species of venomous rattlesnakes — prairie, western, and massasauga — whose bites can cause serious complications and even death if not treated properly, says Kennon Heard, MD, a professor of medical toxicology and pharmacology in the Department of Emergency Medicine at the CU School of Medicine.

We spoke with Heard to learn more about how snakebites are treated and what to know if you are bitten.