most lethal snake in America
Snake Facts And Behaviors

What is the Most Venomous Snake in the United States?

There are approximately 20 species of venomous snakes in America, most of which are rattlesnakes. They can be found in every state, apart from Alaska and Hawaii. You can also encounter them in any habitat, from deserts to forests and even the ocean. Each snake possesses different toxins that have a range of effects, but what is the most venomous snake in the United States?

In terms of venom potency, the Mojave rattlesnake is the deadliest. By some metrics, they’re among the most venomous snakes worldwide. Eastern and western diamondback rattlesnakes bite more people per year, however. And other snakes like the cottonmouth, copperhead, and yellow-bellied sea snake are highly venomous too.

Even though they’re so lethal, though, you’re nine times more likely to die from being struck by lightning than from a venomous snake bite. That’s in equal parts to do with education about snakes, healthcare, and the relative rarity of snakes with venom that is strong enough to kill you.

What Is the Most Poisonous Snake in the USA?

According to the British Journal of Haematology, 1.8 million people are bitten and ‘envenomated’ by venomous snakes per year. Of these people, 125,000 will die.

But because of higher healthcare standards here in the United States, the Center for Disease Control and Prevention estimate that only five U.S. citizens die from snake bites each year.

The majority of deaths occur in areas like southeast Asia, where people catch venomous snakes for regional delicacies and ‘natural medicines.’ Because these people don’t have access to antivenom, many die each year.

1) Eastern Diamondback Rattlesnake

U.S. states with poisonous snakesThe Eastern Diamondback is the longest venomous snake in North America. They can reach up to 8 feet in length, and can reach 10lbs in weight too.

They don’t need to be that heavy—generally, very heavy snakes like anacondas are constrictors that need muscle mass. Eastern Diamondbacks don’t need muscle mass. All they need are their fangs.

They primarily feed on small rodents and mammals, but their venom has the same effect on us as it does on them. It’s hemotoxic, which means it destroys red blood cells.

In plain English, hemotoxic venom can:

  • Stop blood from being able to clot, meaning that you uncontrollably bleed from the bite wound. You can even bleed from the mouth, and, of course, internally.
  • Cause the bitten limb to swell up and change color.
  • Cause severe organ and tissue damage. Given that the consistency of the blood changes, this damages the heart and lungs—and everything else that needs blood to function. So, everything in your body.

Aside from that, eastern diamondbacks live in very close proximity to human populations. They live in the southeast, primarily in Florida, but also anywhere from North Carolina to Alabama and Mississippi. They live in woodland forests and swamps.

Facts About the Eastern Diamondback Rattlesnake

  • They’re endangered in all but name. They haven’t been added to the endangered species list, but their population is only about 3% of what it once was.
  • There’s a myth that the eastern diamondback has to rattle before they strike. That’s not true. They can stay still and silent before striking too, which makes them even more deadly.
  • Even though they’re natural born killers, they still have predators. Hawks and eagles can eat eastern diamondbacks.
  • Their bites are incredibly painful. According to people who’ve been bitten by them, the initial bite feels like two hot needles being jabbed into your skin. It only gets worse from there, with the bite site swelling and aching. You also get intense internal pain which is the result of the venom causing tissue to die.

2) Western Diamondback Rattlesnake

Crotalus atroxThe western diamondback rattler is not that venomous. But what nets them a place on our list is the fact that they produce so much venom, that they can knock out big prey.

There’s a way to tell when a snake produces copious amounts of venom. How? Because their venom glands are much bigger. The venom glands are located towards the back of the head. Snakes that produce and store lots of venom have thin necks, and big wide heads.

Not only that, but since they’re so common, they’re second only to the eastern diamondback in terms of deaths caused. Their venom causes severe pain, internal bleeding, and local swelling. In the worst cases of bite sites that have been heavily envenomated, the tissue will begin to die.

You can find western diamondbacks out west. They range from Texas, down south to Mexico, and west to California. They live out in rocky canyons, but can adapt to many habitats including the desert, grassland and pine-oak forests.

Facts About the Western Diamondback Rattlesnake

  • In Mexico, where the snake has a large population, it kills more people than any other snake.
  • They’re a common victim of hit and runs. Why? Because they like to sit on the blacktop in the evening and at night, while it retains the heat of the sun.
  • They’re a particularly aggressive and defensive species. When you approach one, it’ll usually stand its ground rather than trying to get away. They’ll try rattling, but if that doesn’t scare you, they won’t hesitate to strike.

3) Copperhead

most common snake bite locationCopperheads are another kind of viper. They get their name from their heads, which are—you guessed it—a red, coppery color. People use the term copperhead to refer to a few different snakes, including rat snakes and occasionally water moccasins. But the true copperhead is the North American copperhead snake, scientific name Agkistrodon contortrix.

These snakes are pit vipers. Pit vipers have infrared-sensing pits in their nose which can detect minute temperature variations nearby. This helps them to find prey on the forest floor, in the undergrowth, where mice and other small mammals like to hide. They won’t use their senses to hunt and bite you, thankfully, but they’re still dangerous.

What makes copperheads so dangerous is that they freeze when you approach them. Almost all snakes would rather avoid a person than confront them, because, after all, you’re much bigger and louder than they are. The copperhead doesn’t try and get away, though—it stands its ground. This means that they encounter and therefore bite far more people than other snakes. Not only that, but their range is quite wide, from Texas and the Midwest all the way to the east coast.

Thankfully, though, the copperhead’s venom isn’t as venomous as the other snakes in our list. In fact, it has the least potent venom of any pit vipers (a group which includes cottonmouths and rattlesnakes). Like other similar snakes, their venom is hemotoxic.

Even so, a bite from a copperhead can cause:

  • Sheer, blinding pain (like most bites from pit vipers)
  • Swelling of the wound, and if enough venom was injected, of the whole limb
  • Damage to both muscle and bone tissue
  • In the worst-case scenario, death—if enough venom is injected

It’s extremely rare for anybody to die from a copperhead bite. But their venom can easily kill smaller animals. And, if you’re not careful, a bite could get infected—and in the end, if you don’t seek medical attention, you might need a limb amputated.

Facts About the Copperhead Snake

  • Copperheads can reproduce without mating. This is known as parthenogenesis, and it’s a failsafe that means females can have young even if there aren’t any mates around.
  • A unique protein in copperhead venom called contortrostatin has been found to stop cancer cells from growing, and spreading too.
  • In the south, they’re nocturnal during the summer months. This helps them avoid the worst of the summer’s heat, which is necessary because they can’t regulate their own body heat.
  • Copperheads are much more social than other kinds of snake. You can find them in groups, either sunning themselves on communal basking rocks or getting ready to mate.
  • They’re much more likely to ‘dry bite’ you. This is where they’ve tried scaring you off, but you won’t leave you alone. They bite you, but don’t inject any venom (or hardly use any). They prefer to save their venom for killing prey.

4) Cottonmouth (Water Moccasin)

water moccasinCottonmouths get their name from their distinctive defensive display. When they’re threatened, cottonmouths will gape as wide as they can, as a threat. Because the inside of their mouth is a bright and noticeable white, they got the name ‘cottonmouth.’ The name ‘water moccasin’ has a less clear origin, but they go by both names either way.

Cottonmouths are one of the deadliest snakes—and their reputation goes before them. An old story goes that a woman was having the time of her life, water-skiing, out on a lake. But as she turned, she lost her balance and fell into the water. As the boat turned around to pick her up, her family heard her screaming. She’d fallen into a nest of dozens of cottonmouths just below the surface. When they pulled her from the water, she was covered from head to toe in bites.

There’s a similar story about a group of boys, one of whom jumps in the water before his friends, again into a nest of cottonmouths. This story isn’t true. Cottonmouths don’t group together, to sleep, hunt or mate. Nor do they nest in the water—they prefer hanging out near water, but on land. What is true, though, is that they’re an incredibly venomous snake. If they bite you with the maximum amount of venom they can deliver, it’s enough to kill you. Add in the fact that they’re found all across the southwest, and you’ve got a very deadly snake indeed.

Facts About the Cottonmouth Snake

  • Cottonmouths are the United States’ only venomous water snake.
  • They’re also the world’s only semi-aquatic pit viper. Other pit vipers like rattlesnakes much prefer to stay on land. But cottonmouths can swim quickly and even hunt underwater.
  • Cottonmouths have loads of common names. You might know them as water moccasins, mangrove rattlers, water pit vipers, black water vipers or one of a dozen or more other names.
  • Because they have so many names, they’re often confused for copperheads. Copperheads are wrongly called water moccasins all the time.
  • Cottonmouths are big and strong, thicker around the middle than most other snakes.

5) Eastern Coral Snake

deadliest snakes in the U..S.Coral snakes are the best-known venomous U.S. snake aside from rattlesnakes. That’s because of their distinctive, colorful banded pattern. Despite their colorful pattern, they’re quite shy, and would much rather try and escape from a human than get up close to one.

Whatever the case, they’re exceptionally venomous. Their venom is different to the weapon that rattlesnakes carry. It’s a neurotoxin instead of a hemotoxin. Neurotoxins don’t attack blood cells and organs; they attack the body’s nervous system. The proteins in the venom seek out the nerve endings in our body, and attach to the receptors that pick up signals from them. Once enough receptors have been completely coated in proteins, the brain can’t send signals to the body.

That’s not a minor inconvenience; it’s a major danger. The brain can’t communicate anymore with the heart, lungs or limbs. If the snake bit you with enough venom, this effect would stop your brain from being able to tell your lungs to breathe and your heart to beat. Needless to say, this will kill you.

Coral snakes used to be considered the most dangerous snake in the southeast. That’s why people developed rhymes and mnemonics to remember how to identify one. Today, though, we understand far more about snakes—so we know that they’re only one of many snakes in the southeast that can kill you! That’s why coral snakes deserve a spot on our list for being so venomous, despite being three feet long at most.

Facts About the Eastern Coral Snake

  • Coral snakes are the snake that’s the subject of the rhyme, “Red next to black—friend of Jack. Red next to yellow, kills a fellow!” This is to help distinguish them from scarlet king snakes, which have the same color bands, but in a different order.
  • The rhyme above only applies to North American coral snakes. If you encounter a South American coral snake, this rhyme could get you killed, because their red bands do touch their black bands.
  • There are Texas coral snakes and Arizona coral snakes, too. These populations are isolated from one another, but each has the same black, yellow and red color and pattern.
  • There’s a myth that coral snakes have tiny mouths, so they can’t bite anything other than the webbing between your fingers. This is not true—they can bite anything they want.

6) Yellow-bellied Sea Snake

Hydrophis PlaturusThese snakes are elapids, just like coral snakes. But unlike coral snakes, they live their whole life out at sea. As you can probably guess from their name, they’re a two-tone snake. They’ve got a yellow belly and a brown back, often with no real pattern—just flat color. They’re one of the most widely distributed snake species in the world.

Their geographic range includes:

  • The coasts of Africa, all the way from South Africa up to Ethiopia and the Gulf of Aden
  • All along the coast of southern Asia, from the middle east all the way to India and then Indonesia
  • Up north, the coasts of China and Japan
  • The shores of every island in the south Pacific, from Australia out to Fiji and French Polynesia

And then all the way across the ocean, to Mexico, Costa Rica, Colombia, and the United States. They prefer warmer waters so you’ll find them closer to the equator rather than north towards Washington state or Oregon, for example. Because they live in the ocean, the actual number of bites here in the U.S. is very low.

Their venom, though, is still extremely potent. That’s a pattern that holds true for sea snakes across the world. It several different kinds of neurotoxin, as well as isotoxins. It damages skeletal muscles, causes neuromuscular paralysis, and directly attacks the kidneys.

If they attack you with enough venom, they could easily kill you. In terms of the amount of venom needed to kill somebody, their venom is more potent than a king cobra or an eastern coral snake. So, you better watch out while you’re swimming!

But because sea snakes generally are small and have small fangs, they actually have trouble biting people. Their fangs aren’t strong enough to easily bite through a scuba diver’s suit.

They can also find it difficult to open their jaws wide enough to bite somebody on the leg or arm. It would be like a person trying to take a bite out of a whole watermelon! This means that their venom may be deadly, the snake itself isn’t much of a threat to you.

Facts About the Yellow-bellied Sea Snake

  • They’re completely adapted to living at sea. They mate, eat, and give birth out at sea. They never rest on the sea floor, or on beaches, or on anything else. It’s not clear how they sleep.
  • While they’ll surface for air every once in a while, they can actually breathe in through their skin while underwater.
  • They prefer hunting for small fish to attacking people out for a swim. When you approach one, it’ll try and get away as fast as it can.
  • They’re the most ‘pelagic’ snake in the world. This means that they’re one of the very few snakes that are comfortable swimming out in the open ocean, far away from the shore. That’s why they have such a wide range.
  • Yellow-bellied sea snakes hunt by waiting motionless at the surface of the water. Because fish are attracted to the shadows of things floating, they come straight to the waiting snake. The snake then lashes out at the nearest fish, if they get too close.

7) Mojave Rattlesnake

Crotalus scutulatusThe Mojave rattlesnake, as the name suggests, lives in the Mojave Desert. You can find them in California, Arizona, and northern Mexico too. When you find one in the desert, their coloration and pattern are quite dull.

You’d be forgiven for thinking that they’re generally a dull snake, too. But that’s anything but true. They’re easily the most venomous snake in the United States—and the most venomous rattlesnake in the world.

There are two subspecies of the Mojave rattlesnake. The population in south-central Arizona has a different venom, which isn’t quite as potent as the other subspecies. It has both neurotoxic and hemotoxic effects. This means that if you used an antivenom that works with hemotoxic venoms, you could still die (and vice versa). What makes them so deadly?

  • When a Mojave rattlesnake bites you, the onset of symptoms takes a little while. So, you might think that you’ve been unaffected by their bite, but you’re actually getting closer to death.
  • Their venom works by attacking both your red blood cells and your nervous system. This means that you’ll experience the same difficulty breathing and moving as you will when you’re bitten by a coral snake, plus the internal hemorrhaging of when you’re bitten by a rattlesnake.

Because they prefer high deserts and mountainous regions, you’re not likely to encounter one unless you go looking. This means that despite their very deadly venom, they don’t actually bite and kill that many people. If they had a similar range to the timber rattlesnake, you’d hear about a lot more Mojave rattlesnake deaths.

Facts About the Mojave Rattlesnake

  • The vast majority of the population doesn’t live in the Mojave Desert. Many more of them live in similar arid environments in Mexico instead.
  • They’re so venomous, CBS reported that a boy bitten by one needed 42 vials of antivenom.
  • Back before antivenoms became widely available, bites had a 25% mortality rate.
  • One of the chemicals in their venom was first identified from Mojave rattlesnakes (Mojave toxin.) On its own, it’s not deadly, but combined with the rest of their venom it’s highly potent.

8) Timber Rattlesnake

Crotalus horridusWe’re not done with rattlesnakes. Timber rattlesnakes are the most widespread U.S. species. Unlike many other species, you can find them from as far south as Texas to as far north as Wisconsin and even southern Minnesota.

Also, you can find them almost anywhere along the east coast, from Massachusetts in the north to Florida in the south. This huge geographic range means that they’re the deadliest snake you’ll find in many northern states like Pennsylvania, Wisconsin, New York, and Connecticut. They even used to live in Quebec and Ontario, Canada, before they became extinct that far north.

As the name suggests, it likes to live in forested areas. But they’re also quite happy sitting on rocky ledges and soaking up the sun. They’re frequently encountered by hikers and regular folks alike because of their range and habitat. But it’s not just that that’s earned their place on our list. Their venom is exceptionally potent, just like other rattlesnakes.

While the timber rattlesnake isn’t recognized as having subspecies, snakes in certain regions have different venoms. You can find timber rattlesnakes with neurotoxic effects, some with hemorrhagic effects, and some with both. All timber rattlesnakes also have long fangs, and big venom glands that can store lots more venom than other snakes like coral snakes or sea snakes. This means they deserve a place on our list!

There are a couple of factors, though, which mean that it might not be the #1 deadliest snake here in the U.S. They’re actually relatively shy for a rattlesnake, and will try to avoid people where possible. Not only that, but because of their northern range and adaptation to cold climates, they brumate for long periods of the year. If you didn’t know, brumation is similar to hibernation, where a snake or other reptile enters a period of low activity. This means that they’re asleep from fall until spring, which reduces how much contact they have with people.

Facts About the Timber Rattlesnake

  • They used to live in Canada, but became extinct there. The same is happening in their northern U.S. habitat, like in Massachusetts, where they’re now very rare. They’re disappearing from the whole of New England.
  • Despite their range shrinking, the IUCN still considers them to be a species of Least Concern (as opposed to endangered, or extinct).
  • Remember we said that the kind of venom a timber rattlesnake has varies depending on where it lives? Some have quite a weak venom that’s nowhere near strong enough to kill.
  • The timber rattlesnake is on the Gadsden flag, also known as the ‘Don’t tread on me!’ flag. It was also the snake in Benjamin Franklin’s famous ‘Join, or Die’ cartoon to encourage the colonies to join together and resist British rule. That’s because it had an aggressive reputation, despite being shy for a rattlesnake.
  • Today, it’s the state reptile of West Virginia.

9) Tiger Rattlesnake

Crotalus tigrisThey don’t get their name from being a novel crossbreed between dangerous big cats and venomous snakes. No, they get their name from having tiger-like stripes along their body. Unfortunately, they don’t have orange bodies with black stripes, which would be an incredibly impressive look on a snake. Instead, they’re normally shades of brown and maybe pale orange.

They only have a tiny natural range, in north-western Mexico and south-central Arizona. They have tiny heads in comparison to their bodies, which mean that they also have quite low venom yields. But pound for pound, their venom is the very strongest—at the top with the Mojave rattler. It contains both neurotoxins and myotoxins. Neurotoxins attack the nervous system, while neurotoxins cause muscle necrosis throughout the body.

Not to mention, they’re one of the most aggressive snakes out there. So if you ever encounter one, you better hope you have an antivenom kit with you!

Facts About the Tiger Rattlesnake

  • They’re nocturnal during the summer, to avoid heat levels that would be deadly for them.
  • During the spring or fall, though, they’re diurnal. Being diurnal means that you’re awake during the day—the opposite of nocturnal.
  • They brumate through the winter, hiding in abandoned mammal burrows or crevices in rocks.

Which Snake Bites the Most People?

There are two ways to answer this question. First, you could look at how many people die after being bitten. In terms of deaths, the ‘award’ goes to the rattlesnake—either the eastern or western diamondback rattlesnake.

The problem is that we aren’t always sure which snake bit somebody who died, because only they know what bit them. But more people die in eastern or western diamondback country than anywhere else.

A close second is the timber rattlesnake. Many of the latest deaths by snake in the U.S. were the result of timber rattlesnakes. A man at a campsite in Pennsylvania was bitten by one and airlifted to hospital, but was pronounced dead on arrival.

And according to the Charlotte Observer, another man in South Carolina died recently after he was bitten on his leg by what looked like a timber rattlesnake. Since he was a conservationist of decades’ experience, it goes to show that snake bites really can happen to anybody.

But in terms of the sheer amount of bites, non-fatal or otherwise, the crown belongs to the copperhead. These snakes bite more people than any other snake, in part because they’re so common, but also because of their temperament. While they are venomous, their venom isn’t as potent as the other snakes.

What State Has the Highest Number of Snake Bites?

The U.S. states with most poisonous snakes are Texas and Arizona. But in terms of bites, it’s a different story.

Snake populations are larger in the south. This includes both venomous and non-venomous snakes. The further south you go, the more different species of snake you find, and the larger the population of those snakes generally is. There’s a divide between east and west, though.

In the east, you’ll find:

  • Copperhead snakes
  • Cottonmouths
  • Eastern coral snakes
  • Eastern diamondback rattlesnakes
  • Timber rattlesnakes

But in the west, you’ll find:

  • Arizona coral snakes
  • Prairie coral snakes
  • Mojave rattlesnakes
  • Western diamondback rattlesnakes

So, regarding species, things are pretty even across the board. But in terms of the number of bites, there are more in the southwest than anywhere else. Texas and Florida top the list, but also up there are Georgia, Louisiana, North Carolina, West Virginia, and Oklahoma.

These states are more densely populated than Arizona and New Mexico, for example. So even though you have plenty of venomous species out west, they tend not to encounter people so much.

A big part of the reason why is the habitats that snakes choose. In the southeast, you have far more woodland next to dense urban areas. The most common snake bite location is out in the woods, or near the woods. Anybody who goes hiking, swimming or just exploring is likely to encounter a snake.

Besides that, the proximity to urban settlements means that the snakes will encroach on human spaces too. Out west, many venomous snakes live out in prairies and desert habitats where fewer people go.

But no matter where you live, you can avoid venomous snakes with a little know-how. Don’t approach them, don’t try to touch them, and don’t try to move them out of your way. If you ever find a venomous snake, take a different path. That way, you’ll avoid becoming one of the five snake bite deaths per year.