Overview

By Mayo Clinic Staff

Most snakes aren't dangerous to people. Only about 15% of snakes worldwide and 20% in the United States can inject poison when they bite. These snakes are called venomous. In North America, these include the rattlesnake, coral snake, copperhead and the water moccasin, also called cottonmouth. Their bites can cause serious injuries and sometimes death.

If a venomous snake bites you, call 911 or your local emergency number right away. Do not wait for symptoms to appear. Many emergency rooms have antivenom drugs, which may help you.

If possible, take these steps while waiting for medical help:

• Move far away from the snake.
• Stay still and calm.
• Remove any jewelry, watches or tight clothing before swelling starts.
• Clean the bite with soap and water. Cover or wrap it loosely with a clean, dry bandage.
• Keep the affected limb still and limit movement. If possible, position the affected limb at about heart level to help slow the spread of venom.
• If swelling develops, consider marking the edge of the swelling and noting the time. This can help healthcare professionals assess how far the venom has spread.