The fangs sometimes harbor pathogenic microbial organisms, including Clostridium tetani, and may require an updated tetanus immunization.Most snakebites, from either a venomous or a non-venomous snake, will have some type of local effect. Minor pain and redness occur in over 90 percent of cases, although this varies depending on the site. Bites by vipers and some cobras may be extremely painful, with the local tissue sometimes becoming tender and severely swollen within five minutes. This area may also bleed and blister, and may lead to tissue necrosis. Other common initial symptoms of pit viper and viper bites include lethargy, bleeding, weakness, nausea, and vomiting. Symptoms may become more life-threatening over time, developing into hypotension, tachypnea, severe tachycardia, severe internal bleeding, altered sensorium, kidney failure, and respiratory failure.Bites by some snakes, such as the kraits, coral snake, Mojave rattlesnake, and the speckled rattlesnake, may cause little or no pain, despite their serious and  potentially life-threatening venom. Some people report  experiencing a "rubbery", "minty", or "metallic" taste after being bitten by certain species of rattlesnake. Spitting cobras and rinkhalses can spit venom in a persons eyes. This results in immediate pain, ophthalmoparesis, and sometimes blindness. 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.
Snakes may also be unusually active during especially warm nights when ambient temperatures exceed 21 °C (70 °F). It is advised not to reach blindly into hollow logs, flip over large rocks, and enter old cabins or other potential snake hiding-places. When rock climbing, it is not safe to grab ledges or crevices without examining them first, as snakes are cold-blooded and often sunbathe atop rock ledges.In the United States, more than 40 percent of people bitten by snake intentionally put themselves in harms way by attempting to capture wild snakes or by carelessly handling their dangerous pets—40 percent of that number had a blood alcohol level of 0.1 percent or more.It is also important to avoid snakes that appear to be dead, as some species will actually roll over on their backs and stick out their tongue to fool potential threats. A snakes detached head can immediately act by reflex and potentially bite. The induced bite can be just as severe as that of a live snake. As a dead snake is incapable of regulating the venom injected, a bite from a dead snake can often contain large amounts of venom. Treatment
It may be difficult to determine if a bite by any species of snake is life-threatening. A bite by a North American copperhead on the ankle is usually a moderate injury to a healthy adult, but a bite to a childs abdomen or face by the same snake may be fatal.