There are 20 species of venomous snakes found in the U.S. Of those, 16 are rattlesnakes, 2 are coral snakes, and the other 2 are water moccasins and copperheads. Each snake produces a venom that leads to a range of adverse effects, but what is America’s most venomous snake species?
In terms of venom potency, the coral snake has the most deadly venom, but you’re unlikely to ever get bitten by one due to their short fangs. The Mojave is the deadliest of all rattlesnakes, but eastern and western diamondback rattlesnakes bite more people per year. The cottonmouth and copperhead are also venomous. Yellow-bellied sea snakes are also extremely deadly, but the U.S. is not their natural habitat.
Even though some snakes have lethal venom, you’re 9 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?
The Center for Disease Control and Prevention estimates that only 5 U.S. citizens die from snake bites annually. This is due to superior healthcare standards (antivenom) and less dangerous snakes in America.
This should be contrasted with the rest of the world. According to the British Journal of Haematology, 1.8 million people are bitten and ‘envenomated’ by venomous snakes around the world every year. Of these people, an estimated 125,000 will die.
1) Eastern Coral Snake
Coral snakes are among the best-known venomous U.S. snakes, 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 that which 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 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. However, coral snakes are unlikely to bite you because they only have short fangs. This makes it far more difficult to pierce the skin and deliver potent venom.
Today, 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 kingsnakes, 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.
2) Mojave Rattlesnake
The Mojave rattlesnake lives in the Mojave Desert. You can find them in California, Arizona, and northern Mexico. When you find one in the desert, their coloration and pattern are dull.
You’d be forgiven for thinking that they’re generally a dull snake. They’re easily the most venomous rattlesnake in America.
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. What makes the Mojave rattlesnake so deadly?
- When a Mojave rattlesnake bites you, the onset of symptoms takes a 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 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 hiking. Despite their lethal venom, they don’t 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 majority of the population doesn’t live in the Mojave Desert. Many more of them live in similar arid environments in Mexico instead.
- CBS reported that a boy bitten by one needed 42 vials of antivenom.
- Back before antivenoms became widely available in America, 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.
3) Eastern Diamondback Rattlesnake
The Eastern Diamondback is the longest venomous snake in North America. These deadly snakes can reach 8 feet in length and weigh up to 10lbs.
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 humans as it does on rats. 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.
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 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 eastern diamondbacks have to rattle before they strike. That’s not true. They can stay still and silent before striking.
- Even though they’re natural-born killers, they still have predators. Hawks and eagles can eat eastern diamondbacks.
- Their bites are very painful. 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 the tissue to die.
4) Western Diamondback Rattlesnake
The western diamondback rattler is not that venomous. But what nets them a place on this 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. Their venom glands, towards the back of the head, are much bigger. 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 type of snake.
- They’re a common victim of hit and runs. They 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 escape. They’ll try rattling, but won’t hesitate to strike.
Copperheads 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, 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 that includes cottonmouths and rattlesnakes). Like other similar snakes, their venom is hemotoxic. A bite from a copperhead can cause:
- 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
It’s extremely rare for anybody to die from a copperhead bite. But their venom can easily kill smaller animals.
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.
- 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 most 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.
6) Cottonmouth (Water Moccasin)
Cottonmouths 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. If the water moccasin bit you with the maximum amount of venom they can deliver, it’s enough to kill you. Add given the fact that they’re found all across the southwest, you’ve got a very deadly snake.
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.
- Cottonmouths are big and strong, thicker around the middle than most other types of venomous snakes.
7) Yellow-bellied Sea Snake
These 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 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.
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.
- 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.
- 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.
8) Timber Rattlesnake
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 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.
They like 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.
There are a couple of factors which mean that they might not be the deadliest snake 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. Brumation is like 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 rare. They’re disappearing from New England.
- Despite their range shrinking, the IUCN still considers them to be a species of Least Concern.
- 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
They 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. 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 means 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.
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, 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.
Don’t approach venomous snakes, and never 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 5 U.S. snake bite deaths each year.