Snake venom is highly modified saliva. The venom is part of a whole: the apparatus, which is made up of venom glands that synthesize venom; and an injection system, consisting of modified fangs with which to make the venom penetrate into a prey item or a possible threat or predator. The glands which secrete the zootoxins are a modification of the parotid salivary gland of other vertebrates, and are usually situated on each side of the head below and behind the eye, encapsulated in a muscular sheath. The glands have large alveoli in which the synthesized venom is stored before being conveyed by a duct to the base of channeled or tubular fangs, through which it is ejected. Venoms contain more than 20 different compounds, mostly proteins and polypeptides. Snake venom has two main functions: first, the immobilization of prey and second, the digestion of prey. It is a complex mixture of proteins, enzymes, and various other substances. The proteins are responsible for the toxic and lethal effect of the venom and its function is to immobilize prey, enzymes play an important role in the digestion of prey, and various other substances are responsible for important but non-lethal biological effects. Some of the proteins in snake venom are very particular in their effects on various biological functions including blood coagulation, blood pressure regulation, transmission of the nervous or muscular impulse and have turned out to be pharmacological or diagnostic tools or even useful drugs.

Schlangengifte (Schlangentoxine) sind die physiologisch wirksamen Bestandteile des Giftapparates der Giftschlangen. Sie dienen hauptsächlich der Beutejagd und der Verdauung, daneben auch zur Verteidigung gegen Angreifer. Zur Anzahl der weltweit jährlich durch Giftschlangen verursachten Todesfälle gibt es keine sicheren Angaben, eine neuere Schätzung gibt 21.000 bis 94.000 Todesfälle pro Jahr an.

Slangengif is een mengsel van weefselvernietigende stoffen in een waterige vloeistof die geproduceerd wordt door slangen. Het bijzondere van dit vergif is dat het bestaat uit zeer sterke proteïneases, beter bekend als eiwit(proteïne)-afbrekers.