Vipers can extend their fangs and bite without injecting venom. This is known as a dry bite and is common in human snakebites.

What happens if a viper bites you?

The venom of rattlesnakes and other pit vipers damages tissue around the bite. Venom may cause changes in blood cells, prevent blood from clotting, and damage blood vessels, causing them to leak. These changes can lead to internal bleeding and to heart, respiratory, and kidney failure.

How deadly is a viper bite?

The saw-scaled viper (Echis carinatus) may be the deadliest of all snakes, since scientists believe it to be responsible for more human deaths than all other snake species combined. Its venom, however, is lethal in less than 10 percent of untreated victims, but the snake's aggressiveness means it bites early and often.