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How do you tell the difference between a poisonous and nonpoisonous snake?

Being able to identify whether a snake is poisonous or not can literally be a matter of life and death, especially if you spend a lot of time hiking or camping outdoors. While there are some general rules of thumb when it comes to identifying poisonous snakes, it’s important to learn how to distinguish specific species based on their unique markings and behaviors.

There are two main types of venomous snakes in the United States: vipers and coral snakes. Within these two families, there are dozens of different species with distinct appearances and habits. The key to staying safe around snakes is learning how to properly identify venomous species based on certain visual and behavioral cues.

When encountering any snake in the wild, the first rule is to give it space and not try to touch or handle it in any way. If you aren’t able to confidently identify it as harmless, then treat it as potentially dangerous. It’s better to be cautious and keep your distance. With knowledge and experience identifying snakes, you’ll be able to relax around the harmless ones while taking proper precautions around venomous species.

Differences Between Poisonous and Venomous

Before going any further, it’s important to clarify the difference between a poisonous snake and a venomous snake. These terms are not interchangeable.

Poisonous snakes have toxins inside their bodies, especially in their skin and organs. The toxins take effect when another animal eats or touches the snake. Poison dart frogs operate similarly, having poisonous secretions. There are no snakes that are truly poisonous.

Venomous snakes, on the other hand, produce venom in specialized glands and can inject this venom through fangs or spurs. The venom takes effect rapidly when injected into prey or a potential threat. All venomous snakes are dangerous if they bite you.

How to Identify Venomous Snakes in the U.S.

There are four main types of venomous snakes found in the continental United States: rattlesnakes, copperheads, cottonmouths (also called water moccasins), and coral snakes. The vast majority of venomous snakebites in the U.S. come from these four genera of snakes.


Rattlesnakes are easily identifiable by the signature rattle at the end of their tail. When threatened, they make a loud buzzing noise by rapidly shaking their rattle. However, it’s important to note that not all rattlesnakes retain their rattle through life, so you can’t definitively rule out a rattlesnake just because you don’t hear rattling. There are over 30 species of rattlesnakes found throughout the Americas in diverse habitats from swamps to deserts to mountain forests.

Some key traits for identification:

  • Triangular heads that are often much wider than the neck
  • Vertical slit-like pupils
  • Heat-sensing facial pits between the nostrils and eyes
  • Tan, brown, olive, or grey camouflage patterns
  • Dark bands, chevrons, or diamonds running down their backs


Copperheads have chunky, reddish-brown bodies with hourglass-shaped darker bands down their length. They blend in well with leaf litter and live throughout the eastern and central United States. Copperheads are not known for being aggressive unless threatened. More than half of all snakebites in the U.S. are attributed to copperheads.

Some key traits for identification:

  • Pink, tan, or copper-colored heads
  • Slitted pupils
  • Blocky, hourglass patterns
  • Squat, heavy-bodied
  • Live in wooded, brushy areas


As their name suggests, cottonmouths often showcase the white interior of their mouths when threatened. They have heavy bodies and often swim in the lakes, ponds, and swamps of the southeastern U.S. Cottonmouths have a reputation for being aggressive when approached.

Some key traits for identification:

  • Stout, dark brown or black bodies
  • Bands as juveniles that fade to solid coloring as adults
  • Triangular heads wider than the neck
  • Vertical pupils
  • Live around water

Coral Snakes

Coral snakes have distinctive red, yellow, and black banding throughout their slender bodies. They are related to cobras and live in the southern U.S. states. Coral snakes have round pupils and a black snout. Their venom is highly potent, but they are not aggressive and rarely bite humans.

Some key traits for identification:

  • Slender bodies
  • Red, yellow, and black bands running the length of their bodies
  • Red bands touch yellow bands (white bands separate the red and yellow bands on lookalike scarlet kingsnakes)
  • Round pupils
  • Small heads the same width as neck
  • Live in forested and scrub areas
Species Geographic Range Key Identifiers
Rattlesnakes Throughout the Americas Triangular heads, slit pupils, facial pits, rattles, tan camouflage with dark diamonds
Copperheads Eastern and central North America Hourglass patterns, coppery color, chunky bodies
Cottonmouths Southeastern U.S. Black or brown, live around water, white mouths
Coral snakes Southern U.S. states Red, yellow, and black banding, round pupils, slender bodies

Tips for Identification

In addition to looking for distinguishing physical characteristics, here are some other tips that can aid in properly identifying venomous snakes:

  • Learn local species. Only certain snakes live in certain parts of the country. Knowing which venomous snakes are plausible in your area makes identification easier.
  • Watch their movement. The way a snake moves and carries itself provides clues. Venomous snakes often move in an efficient, deliberate straight line compared to more wandering movements of nonvenomous species.
  • Note their habitat. While habitats do overlap at times, cottonmouths frequent aquatic environments, copperheads like wooded areas, and rattlesnakes live in more open, rocky terrain.
  • Be familiar with lookalikes. Certain harmless species like milk snakes and kingsnakes are frequently mistaken for coral snakes because of similar coloring. Learn the subtle differences.
  • Identify age. Young venomous snakes sometimes look very different from adults. Baby copperheads have yellowish green tails, for example.
  • Don’t rely on folk wisdom. Myths like “triangle heads are always venomous” or “coiling to strike means it’s harmless” are not reliable ways to identify snakes.

With experience and knowledge of snake behaviors and environments, you’ll become adept at distinguishing dangerous from benign snakes. When in doubt, err on the side of caution and give snakes their space in the wild.

What to Do If Bitten by a Venomous Snake

If you are bitten by a venomous snake, here are the steps you should immediately take:

  1. Remain calm and immediately move beyond the snake’s striking distance.
  2. Call 911 or emergency services if possible. Seek medical attention as rapidly as possible.
  3. Remove jewelry or tight clothing from the area of the bite as swelling can occur quickly.
  4. Position yourself to keep the bite area immobilized and below heart level if able.
  5. Clean the bite area with soap and water if possible but don’t flush heavily or attempt to suction out the venom.
  6. Take photos of the snake from a safe distance if it can be done safely and without delaying medical care.
  7. Monitor symptoms of nausea, numbness, blurred vision, and difficulty breathing which can set in rapidly with venom.
  8. Keep the bite victim as still as possible until anti-venom can be administered.

Never make cuts at the site of a venomous snakebite or attempt to suction out the venom. This can cause infection and actually increase how quickly venom spreads through the body. Leave treatment to anti-venom administration experts at hospitals.

Preventing Snake Encounters

Using caution and proper preparedness, snakebites can often be avoided in many cases:

  • Wear sturdy boots and thick pants when hiking.
  • Avoid reaching into spaces where snakes may hide like under rocks or logs.
  • Use extra caution around pools of water.
  • Stay on trails and avoid high grass when possible.
  • Keep hands and feet where you can see them when climbing over logs.
  • Make noise or carry a stick when walking to alert snakes.
  • Never try to handle or kill a venomous snake, even if it is dead.

Snakes benefit local ecosystems by controlling pests and don’t want to bite humans. Respect their space, and they’ll respect yours. But preparedness in snake country can help avoid bad encounters. Knowing how to identify dangerous snakes gives you confidence outdoors.


Being able to distinguish a venomous snake from a harmless one takes practice more than anything else. Educating yourself on local species, their key identifying features, habitats, and behaviors goes a long way for safe encounters. While some general rules of thumb exist, each species has distinctive markings and patterns to recognize. With experience in the field, you’ll become adept at making the critical distinctions that could save a life. If there’s ever doubt, don’t risk it – give snakes their space and leave identification to the experts. The most important tip is to remain calm and get medical help rapidly in the event of a venomous snakebite to prevent serious complications from the toxins.