[2] The venom may cause bleeding, kidney failure, a severe allergic reaction, tissue death around the bite, or breathing problems.

[3][12][13] Allergic reactions to snake venom can further complicate outcomes and can include anaphylaxis, requiring additional treatment and in some cases resulting in death.

[26][27] Some Australian elapids and most viper envenomations will cause coagulopathy, sometimes so severe that a person may bleed spontaneously from the mouth, nose, and even old, seemingly healed wounds.

Children playing within short distances of their homes crawl under porches, jump into bushes, pull boards of wood from a pile and are bitten.

Some dry bites may also be the result of imprecise timing on the snake's part, as venom may be prematurely released before the fangs have penetrated the person.

As open grasslands replaced forested areas in parts of the world, some snake families evolved to become smaller and thus more agile.

The venom itself evolved through the process of natural selection; it retained and emphasized the qualities that made it useful in killing or subduing prey.

[40][39] Other research on Toxicofera, a hypothetical clade thought to be ancestral to most living reptiles, suggests an earlier time frame for the evolution of snake venom, possibly to the order of tens of millions of years, during the Late Cretaceous.

[citation needed] Venom in many snakes, such as pit vipers, affects virtually every organ system in the human body and can be a combination of many toxins, including cytotoxins, hemotoxins, neurotoxins, and myotoxins, allowing for an enormous variety of symptoms.

[citation needed] When in the wilderness, treading heavily creates ground vibrations and noise, which will often cause snakes to flee from the area.

It is advised not to reach blindly into hollow logs, flip over large rocks, and enter old cabins or other potential snake hiding places.

[46] It is also important to avoid snakes that appear to be dead, as some species will roll over on their backs and stick out their tongue to fool potential threats.

The outcome of all snakebites depends on a multitude of factors: the type of snake, the size, physical condition, and temperature of the snake, the age and physical condition of the person, the area and tissue bitten (e.g., foot, torso, vein or muscle), the amount of venom injected, the time it takes for the person to find treatment, and finally the quality of that treatment.

[2][49] An overview of systematic reviews on different aspects of snakebite management found that the evidence base from majority of treatment modalities is low quality.

[50] An analysis of World Health Organization guidelines found that they are of low quality, with inadequate stakeholder involvement and poor methodological rigour.

Attempting to catch or kill the offending snake also puts one at risk for re-envenomation or creating a second person bitten, and generally is not recommended.

[59] The object of pressure immobilization is to contain venom within a bitten limb and prevent it from moving through the lymphatic system to the vital organs.

Antivenom is made by injecting a small amount of venom into an animal (usually a horse or sheep) to initiate an immune system response.

In extreme cases, in remote areas, all of these misguided attempts at treatment have resulted in injuries far worse than an otherwise mild to moderate snakebite.

In worst-case scenarios, thoroughly constricting tourniquets have been applied to bitten limbs, completely shutting off blood flow to the area.

For instance, the metal chelator dimercaprol has recently been shown to potently antagonize the activity of Zn2+-dependent snake venom metalloproteinases in vitro.

When isolated, fang sheath retraction has experimentally been shown to induce very high pressures in the venom delivery system.

[90] A similar method was used to stimulate the compressor musculature, the main muscle responsible for the contraction and squeezing of the venom gland, and then measuring the induced pressures.

For these reasons, the pressure balance hypothesis concludes that external factors, mainly the bite and physical mechanics, are responsible for the quantity of venom expelled.

[91] This combined with the ability to partially retract their fang sheath by displacing the palato-maxillary arch and contracting the adductor mandibulae, allows the spitting cobras to create large pressures within the venom delivery system.

The ancient Egyptians recorded prescribed treatments for snakebites as early as the Thirteenth Dynasty in the Brooklyn Papyrus, which includes at least seven venomous species common to the region today, such as the horned vipers.

The object was regarded as a divinely empowered instrument of God that could bring healing to Jews bitten by venomous snakes while they were wandering in the desert after their exodus from Egypt.

[97] Snakebite as a surreptitious form of murder has been featured in stories such as Sir Arthur Conan Doyle's The Adventure of the Speckled Band, but actual occurrences are virtually unheard of, with only a few documented cases.

[95][98][99] It has been suggested that Boris III of Bulgaria, who was allied to Nazi Germany during World War II, may have been killed with snake venom,[95] although there is no definitive evidence.

[102][103] In 2019, they launched a strategy to prevent and control snakebite envenoming, which involved a program targeting affected communities and their health systems.