How Venomous Are Coral Snakes? Neurotoxic Venom Explained

What makes coral snake venom so potent

Coral snakes belong to the family Elapidae, the same group as cobras, mambas, kraits and sea snakes. Like most elapids, they rely on neurotoxins: venom proteins that stop nerves from passing signals to muscles. Without those signals, muscles weaken and eventually stop working, including the muscles that control breathing.

The venom is built for the coral snake’s usual prey, other snakes and slender lizards, which must be subdued quickly before they can wriggle free or bite back. In standard laboratory tests on mice, eastern coral snake venom is among the most toxic of any snake in the United States, considerably stronger per milligram than the venom of most rattlesnakes.

Coral snake venom also contains enzymes that can damage muscle, but it causes little of the swelling, bruising and tissue damage typical of rattlesnake bites. That difference matters, because a coral snake bite can look harmless at first.

Short fangs, small doses

Potency is only half the story. The other half is delivery. A coral snake has a pair of short, fixed fangs at the front of the upper jaw, and a small mouth. Rattlesnakes, by contrast, have long, hinged fangs that fold forward to inject large amounts of venom in a fraction of a second.

Estimates suggest that an eastern coral snake usually delivers only a few milligrams of dried venom in a bite, while the dose that could kill an adult person is thought to be around 5 mg. That margin is thin, but many bites deliver little or no venom. These are called dry bites, and studies disagree on how common they are, with estimates ranging from about a quarter to more than half of all bites.

The “they have to chew” myth

A popular belief says that coral snakes must chew on a person for a long time to inject venom, so a quick bite is harmless. This is false. Coral snakes often hang on and make chewing motions, which helps venom flow down their short fangs, but a quick bite can still inject a dangerous amount.

Another old claim is that coral snakes can only bite small, thin parts of the body, such as a finger or the skin between fingers. Their mouths are small, and most recorded bites are indeed on the hands and fingers, but that is because the victims were handling the snake. Any bite should be taken seriously.

What a bite does to a person

Because the venom targets nerves, a coral snake bite may cause only mild pain and little swelling at first. Symptoms can be delayed for several hours, sometimes much longer. When they appear, they can include numbness, drooping eyelids, double vision, slurred speech, difficulty swallowing, drooling and spreading muscle weakness. In severe cases the muscles that control breathing become paralyzed.

This delay is what makes coral snake bites tricky: someone may feel fine and decide not to get help. Anyone bitten by a coral snake, or by any snake that might be one, should seek emergency medical help immediately: call 911. Hospitals can monitor the patient and support breathing, and an antivenom for North American coral snakes has been available since the 1960s.

How rare are coral snake bites?

The CDC estimates that 7,000 to 8,000 people are bitten by venomous snakes in the United States each year, and that about five of them die. Coral snakes account for less than 1 percent of these bites. The rest are mostly from rattlesnakes, copperheads and cottonmouths.

Deaths from coral snakes are extremely rare. Only a handful have been documented in the US over the past century. The most recent widely reported case, in Florida in 2006, was the first death from an eastern coral snake in several decades, and the man involved did not seek medical treatment. The eastern coral snake itself is secretive and reluctant to bite, and most bites happen when people deliberately pick one up, sometimes because they mistook it for a harmless look-alike. To learn the difference, see does the “red touches yellow” rhyme work?

How the three US coral snakes compare

The eastern coral snake and the Texas coral snake are the two medically important species in the US. The Texas coral snake is a little larger on average and has a somewhat larger venom yield. The small Sonoran coral snake of Arizona and New Mexico has potent venom too, but its tiny size and very small fangs mean that no human deaths from its bite have been reported.

Elsewhere in the Americas, more than 80 species of coral snakes range south to Argentina. They also cause only a small share of snakebites, mostly because of their secretive habits. Asia has its own coral snakes, including the blue Malaysian coral snake, whose venom glands extend about a quarter of the way down its body and whose venom over-stimulates nerves rather than simply blocking them.

How coral snakes compare with the world’s deadliest snakes

Coral snakes are not usually listed among the world’s most dangerous snakes. Species such as the inland taipan, with even more potent venom, or the saw-scaled vipers and Indian cobras, which bite huge numbers of people, are far more significant to human health. For context, see the most venomous snakes in the world and venomous snakes in the US.

The coral snake’s real lesson is that potency and danger are not the same thing. A snake with powerful venom that hides underground and rarely bites causes far fewer injuries than a common snake with weaker venom that lives close to people. Leaving coral snakes alone keeps the risk close to zero.