Snake And Lizard Bites

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Topic Overview

Poisonous snake or lizard bite

A bite from a poisonous (venomous) snake or lizard requires emergency care. If you have been bitten by a snake or lizard that you know or think might be poisonous, call 911 or other emergency services immediately. Do not wait for symptoms to develop.

If you are not sure what type of snake or lizard bit you, call the Poison Control Center immediately to help identify the snake or lizard and find out what to do next. Medicine to counteract the effects of the poison (antivenom) can save a limb or your life.

It is important to stay calm.

Poisonous snakes or lizards found in North America include:

• Pit vipers (family Viperidae), such as the rattlesnake, copperhead, and water moccasin (also called cottonmouth).
• Coral snake (family Elapidae).
• Gila monster and Mexican beaded lizard.

Maine, Alaska, and Hawaii are the only states that do not have at least one poisonous snake species in the wild.

Poisonous snakebite

Symptoms of a pit viper snakebite often appear from minutes to hours after a bite. Severe burning pain at the site usually begins within minutes, and then swelling starts spreading out from the bite.

Factors that affect the severity of a poisonous snake or lizard bite include the:

• Type and size of the snake or lizard.
• Amount of venom injected (if any).
• Potency of the venom injected.
• Location and depth of the bite.
• Number of bites and where they occurred on the body.
• Age, size, and health of the person who was bitten.

If you do not develop symptoms within 8 to 12 hours, it is possible that no venom was injected; this is called a dry bite. At least 25%, perhaps up to 50%, of bites are dry. If poison is released in the bite, about 35% of the bites have mild injections of poison (envenomations), 25% are moderate, and 10% to 15% are severe.

It is important to remember that a snake only injects part of its venom with each bite, so it is still dangerous after the first strike. A bite from a young snake can be serious. And a dead snake, even one with a severed head, can still bite and release venom by reflex action for up to 90 minutes after it dies. Even if you do not develop symptoms within 8 hours, continue to watch for symptoms for 2 weeks or more.

Nonpoisonous snake or lizard bite

Most snakes and lizards in North America are not poisonous. Bites may be frightening, but most do not cause serious health problems. A bite from a small nonpoisonous snake might leave teeth marks, a minor scrape, or a puncture wound without other symptoms. Home treatment often relieves symptoms and helps prevent infection.

Although most nonpoisonous snakebites can be treated at home, a bite from a large nonpoisonous snake (such as a boa constrictor, python, or anaconda) can be more serious. In North America, these snakes are often found in zoos, but they may also be kept as exotic pets. The force of the bite can injure the skin, muscles, joints, or bones. Other problems can occur with a nonpoisonous snake or lizard bite even if the reptile is small. A snake or lizard's tooth may break off in a wound or a skin infection may develop at the site of the bite.

Review the Emergencies and Check Your Symptoms sections to determine if and when you need to see a doctor.

Last updated:	June 19, 2008
Author:	Jan Nissl, RN, BS
Reviewed By:	William M. Green, MD - Emergency Medicine, Sean P. Bush, MD, FACEP - Emergency Medicine and Envenomation Specialist
Editors:	Susan Van Houten, RN, BSN, MBA, Tracy Landauer