Venomous Snakes

Some Most Venomous (Poisonous) Snakes to Humans

Two major families of snakes account for most venomous snakes dangerous to humans.

The Elapid


1. The Elapid family and their snakes includes:

  • The Cobras (Naja and other genera) of Asia and Africa;
    King cobra (Ophiophagus hannah), a dangerous Asian elapid and longest of the venomous snakes at around 4 m (13 ft).
  • The Mambas (Dendroaspis) of Africa; the kraits (Bungarus) of Asia;
    Black mamba (Dendraspis polylepis), an extremely fast, large, and dangerous African elapid.
  • The Coral snakes (Micrurus) of the Americas; and the Australian elapids, which include the coastal taipan (Oxyuranus scutellatus);
    Coral snake (Micrurus fulvius), a shy American elapid that accounts for only about 1% of venomous snakebites in the United States.
  • Tiger snakes (Notechis), king brown snake (Pseudechis australis)
  • Death adders (Acanthophis).

Highly venomous sea snakes are closely related to the Australian elapids.


The Viper


1. The viper familyand their snakes includes:

  • The Rattlesnakes (Crotalus) (Western diamondback rattlesnake and timber rattlesnake);
    Western diamondback rattlesnake (Crotalus atrox), an American pit viper, with rattle vibrating. This is one of the most dangerous snakes of North America.
  • Timber rattlesnake (Crotalus horridus), American pit viper.
  • Moccasins (Agkistrodon);
    Cottonmouth or water moccasin
     (Agkistrodon piscivorous), American pit viper usually found in or near water.
  • Northern copperhead (Agkistrodon contortrix), an American pit viper. Bites by this species tend to be less severe than rattlesnake or water moccasin bites but still require urgent medical attention.
  • Lance-headed vipers (Bothrops) of the Americas
  • The saw-scaled vipers (Echis) of Asia and Africa
  • The Russell’s viper (Daboia russellii) of Asia
  • The puff adder (Bitis arietans) and Gaboon viper (Bitis gabonica) of Africa.

Most species of the most widely distributed and diverse snake family, the Colubrids, lack venom that is dangerous to humans. Some species, however, including the boomslang (Dispholidus typus), twig snakes (Thelotornis), the Japanese garter snake (Rhabdophis tigrinus), and brown tree snake (Boiga irregularis), can be dangerous. Other members of this family, including American garter snakes, kingsnakes, rat snakes, and racers, are harmless to humans.


Some venomous snakes also cause symptoms specific to their type.



Rattlesnakes are easily identifiable. They have rings at the end of their tails that shake when they feel threatened. This makes a rattling sound and is a warning for you to back away. Rattlesnakes are the largest of the venomous snakes and account for many of the venomous bites in the U.S. each year. These snakes can be found in nearly any habitat across the country. They like open areas where they can rest in the sun such as rocks, and logs.


Symptoms specific to rattlesnake bites are immediate and include:

  • severe pain
  • drooping eyelids
  • low blood pressure
  • thirst
  • tiredness or muscle weakness

Water moccasins or cottonmouths


The water moccasin is another type of pit viper. This snake is also known as a cottonmouth, because the inside of its mouth is lined with a white, cottony material. The water moccasin’s average size is between 50 to 55 inches. Adults have dark tan to black skin with faint dark brown or black crossbands. Young snakes have brown or orange crossbands with a yellow tail. These snakes are found in the southeastern states, usually in or near water. They don’t scare easily, and will defend themselves should they feel threatened.


Water moccasin bites share symptoms with copperhead bites. Specific symptoms include:

  • immediate pain and symptoms
  • change in skin color
  • shock
  • low blood pressure
  • weakness



Copperheads are reddish or gold in color with hourglass-shaped bands. This snake is typically 18 to 36 inches in length. Copperheads are mostly found in forests, swamps, rocky areas, and rivers in the eastern states (as far as Texas). They are not aggressive. Most copperhead bites occur if you accidentally step on or near one.


Copperhead snake bites share symptoms with water moccasin snake bites. Symptoms can include:

  • immediate pain and symptoms
  • change in skin color
  • shock
  • low blood pressure
  • weakness


Coral snakes

coral snake2

Coral snakes have black, yellow, and red banding and are often confused with non-venomous king snakes. You can distinguish a coral snake by the fact that the red bands touch the yellow bands. They live in the woods, marshes, and sandy areas of the South. Coral snakes typically hide underground and in leaf piles.


Symptoms specific to coral snake bites include:

  • pain that is not immediate
  • symptoms that set in hours after the bite
  • convulsions
  • drooping eyelids
  • change in skin color
  • stomach pain
  • difficulty swallowing
  • headache
  • shock
  • paralysis