Overview

Pit vipers, such as the rattlesnake, copperhead, and cottonmouth (also called water moccasin), are poisonous (venomous) snakes. They leave one, two, or three puncture marks on the skin, but you won't always see any marks.

Symptoms of a pit viper snakebite usually appear within a few minutes to a few hours after a bite and may include:

• Severe, immediate pain with rapid swelling.
• Bruising of the skin.
• Trouble breathing.
• Changes in heart rate or rhythm.
• A metallic, rubbery, or minty taste in the mouth.
• Numbness or tingling around the mouth, tongue, scalp, feet, or the bite area.
• Swelling in lymph nodes near the bite.
• Signs of shock.

Other symptoms may be caused by the bite itself or from fear or worry after being bitten. You may:

• Faint or feel like you might faint.
• Sweat and have chills.
• Be sick to your stomach or vomit.
• Feel weak or dizzy.

The severity of symptoms will depend on the type of snake that bit you, how much venom was injected with the bite (envenomation), and your personal health risks. Even if you do not have symptoms within 8 hours of a bite, continue to watch for symptoms for up to 2 weeks.

If you do not have symptoms within 8 to 12 hours, the snake might not have injected any venom; this is called a dry bite. At least 25%, perhaps up to 50%, of bites are dry.

• Dry bites or bites where only a very small amount of venom is injected may cause slight bleeding, pain, and swelling at the bite injury.
• If a moderate amount of venom was injected, you are more likely to have severe pain, swelling of the whole limb, and general ill feelings, such as nausea, vomiting, and weakness. Swelling of the whole limb is an effect of the venom and can cause compartment syndrome. This is rare.
• Large amounts of venom usually cause severe pain and severe swelling. You may have trouble breathing, moderate to severe bleeding, and signs of shock after this type of bite.

If venom is injected, about 35% are mild envenomations, 25% are moderate envenomations, 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 can still hurt you after the first strike. A dead snake, even one with a severed head, can bite and release venom through reflexes for up to 90 minutes after it dies.