Rattlesnakes are venomous. If you’re bitten by one it can be dangerous, but it’s very rarely fatal if treated within the first 6 hours, ideally the first hour with antivenom treatment from your local hospital. The venom from the majority of rattlesnake bites will damage tissue and affect your circulatory system by destroying skin tissues and blood cells and by causing you to hemorrhage internally. If you are bitten by a rattlesnake, seek medical attention at once.