MSD Manual

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Reviewed/Revised May 2023
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Both poisonous and nonpoisonous snakes bite people. Poisonous snakes may inject venom (poison) when they bite. In the United States, people rarely die from snakebites. Some other countries have different poisonous snakes that kill many people.

Only a few types of poisonous snakes live in the United States:

  • Most common: pit vipers, such as rattlesnakes, copperheads, and cottonmouths

  • Rare: coral snakes

Most poisonous bites are caused by rattlesnakes. Coral snake bites are very rare.

What are the symptoms of a snakebite?

Nonpoisonous snakebites cause small puncture wounds that are slightly painful. However, if you're scared about being bitten, you may breathe fast, feel sweaty and sick to your stomach, and feel your heart pounding. These symptoms may make you think you have a poisonous snakebite.

Poisonous snakebites cause different symptoms depending on:

  • The type of snake

  • The snake's size (bigger snakes carry more venom)

  • The amount of venom injected (a snake can put different amounts of venom in a bite)

  • What part of you was bitten

  • Your age, size, and health

Symptoms of a poisonous pit viper snakebite

Not all pit viper bites involve venom. If the bite doesn't hurt or swell in the first 30 to 60 minutes, you probably didn't get any venom. If the bite oozes, that can be a sign of venom.

After a venomous bite from a pit viper snake, you'll have:

  • Redness and swelling, about 30 to 60 minutes after the bite

  • Bruising and tightness, appearing 3 to 6 hours after the bite

  • Blisters filled with blood near the bite

You may get a lot of swelling. The swelling usually keeps getting worse for a couple of days.

If you got a lot of venom, you may also have:

  • Weakness and confusion

  • Nausea (feeling sick to your stomach) and vomiting (throwing up)

  • Bleeding gums

  • Blood in your throw-up, stool (poop), or urine

  • Breathing trouble, especially if a Mojave rattlesnake bit you

Hours later, you may have

  • Headache

  • Blurry vision

  • Drooping eyelids

  • Dry mouth

  • Tingling, numbness, or a metal taste in your mouth, if a rattlesnake bit you

Symptoms of a coral snakebite

  • Little or no pain or swelling around the bite

  • After several hours, the bite may tingle

  • Muscle weakness, which becomes more severe over time

You may also have:

  • Blurry vision or double vision

  • Weakness and confusion

  • Trouble breathing

  • Trouble talking or swallowing

What do I do if I'm bitten by a snake?

If you're bitten by a snake and have symptoms, go to the hospital right away. While you're waiting for medical help:

  • Move away from the snake

  • Keep the bitten arm or leg below the level of your heart

  • Try to stay calm and still

  • Take off jewelry and tight clothing from the bite area

Things you shouldn't do:

  • Don’t cut the bite open or suck the bite to try to get the venom out (doesn't work)

  • Don’t use an ice pack (harmful)

  • Don't put on a tight band or tourniquet (harmful)

  • Don't try to catch the snake to bring to the doctor (if the snake is dead, a cellphone picture may help)

If medical care is far away (like when you're out camping) and you don't have any symptoms, clean the bite with soap and water. Watch for signs of infection like you would with any other shallow wound.

How can doctors tell if the snakebite is poisonous?

To find out if the snakebite is poisonous, your doctor will look at the bite marks. The doctor will ask what the snake looked like. The doctor will also ask about your symptoms.

Is That a Pit Viper?

Pit vipers have certain features that can help distinguish them from nonvenomous snakes:

  • Vertical slitlike pupils

  • Pits between the eyes and nose

  • Retractable fangs

  • Rows of single scales across the underside of the tail

  • Triangular heads (like an arrowhead)

Nonvenomous snakes tend to have the following:

  • Rounded heads

  • Round pupils

  • No pits

  • No fangs

  • Rows of double scales across the underside of the tail

If people see a snake with no fangs, they should not assume it is nonvenomous because the fangs may be retracted.

Is That a Pit Viper?

The shape of the bite can sometimes help you know if the snake is poisonous:

  • Nonpoisonous snakebites usually leave rows of small scratches

  • Bites from poisonous snakes are usually one or two large punctures (holes)

How do doctors treat a snakebite?

For a nonpoisonous snakebite, doctors will treat it the same way they treat other puncture wounds. They will:

For a poisonous snakebite, the doctor will:

  • Usually give you snake antivenom (medicine that works against a specific poison) through an IV (into your vein)

  • Keep you in the hospital for 6 to 8 hours to watch your symptoms, and longer if needed

  • Put you in intensive care in the hospital, if you took in a large amount of venom

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