Rattlesnakes are the most widely known of the pit viper snakes that can inject venom when they bite. They are found throughout the United States and parts of Canada. They are responsible for most of the venomous snakebites in North America. They leave one, two, or three puncture marks on the skin, but you won't always see any marks.

Rattlesnakes generally will not attack unless they feel threatened or trapped. Stay safe by leaving them alone and giving them lots of space. Rattlesnakes can be up to 8 ft (2.5 m) long and have:

• Rattles at the end of the tail. Young snakes may only have one rattle that does not make the rattle sound.
• Diamond-shaped markings, blotches, or speckles down the back.
• A deep pit between each eye and nostril.
• A triangular head, slit-shaped pupils, and fangs.
• A single row of scales on the underside of the tail.

Symptoms of a rattlesnake bite usually appear from minutes to hours after a bite and can include:

• Severe, immediate pain with rapid swelling.
• Bruising or blisters near the bite.
• Nausea or vomiting.
• Trouble breathing.
• Changes in heart rate or rhythm.
• A metallic, rubbery, or minty taste in the mouth.
• Numbness or tingling around the face or in the arms or legs.
• Signs of shock.

If you think you have been bitten by a rattlesnake, call 911 or other emergency services immediately.