If a snake bites you, what happens next depends almost entirely on whether the snake was venomous and whether it actually injected venom. Roughly 50% of bites from venomous snakes worldwide are “dry bites,” meaning no venom enters your body. In some regions that figure is even higher, with one Sri Lankan hospital recording dry bites in 86% of venomous snake admissions. But when venom is injected, the effects range from intense local pain and swelling to life-threatening problems with breathing, bleeding, or organ function.
What You Feel Right Away
The first thing most people notice is pain. Venomous bites typically produce burning or throbbing pain that starts at the wound and spreads up the limb. You’ll usually see two puncture wounds from the fangs. Nonvenomous bites leave smaller marks arranged in an arc shape, reflecting the snake’s full set of teeth rather than two prominent fangs.
Swelling can appear within 15 minutes of a venomous bite, especially from vipers. Over the next two to three days it may become massive, spreading across the entire limb and even onto the trunk. That swelling can persist for up to three weeks. If a viper bites you and there’s no swelling after two hours, that’s a reliable sign no venom was injected.
Even with a dry bite, your body’s stress response can mimic envenomation. Flushing, rapid heartbeat, breathlessness, sweating, dizziness, and tightness in the chest are all common and driven by anxiety rather than venom. This makes it hard to tell in the moment whether you’ve been envenomed, which is why every venomous snake bite warrants emergency medical evaluation.
How Different Venoms Affect Your Body
Snake venoms aren’t all alike. They fall into three broad categories based on what they attack, and some snakes produce venom that combines more than one type.
- Neurotoxic venom disrupts the signals between your nerves and muscles. It interferes with the chemical messengers that tell your muscles to contract, which can lead to drooping eyelids, blurred vision, difficulty swallowing, and in severe cases, paralysis of the muscles you use to breathe. Cobras, mambas, kraits, and taipans produce neurotoxic venom.
- Hemotoxic venom targets your blood and blood vessels. Some components force your blood to clot uncontrollably, consuming your clotting factors until your blood can no longer clot at all. Others directly break down the walls of tiny blood vessels, causing internal bleeding. You might notice persistent bleeding from the fang wounds, bleeding gums, nosebleeds, or blood in your vomit. Vipers and rattlesnakes are the primary source of hemotoxic envenomation.
- Cytotoxic venom destroys cells and tissue at the bite site. It breaks down cell membranes, killing skin, muscle, and other soft tissue. This is what leads to the dramatic blackened, dying tissue you may have seen in photos of cobra or pit viper bites. In severe cases, the tissue destruction is deep enough to require surgical removal of dead tissue or, rarely, amputation.
Nausea and vomiting are common warning signs across all types of severe envenomation, regardless of which venom is involved.
What Happens at the Hospital
One of the first things medical teams do is assess whether venom was actually injected and, if so, how much. A simple but effective tool used worldwide is the 20-minute whole blood clotting test. A small sample of your blood is placed in a glass tube and left undisturbed for 20 minutes. If it remains liquid instead of forming a clot, that confirms your blood’s clotting system has been disrupted by venom. This test helps guide treatment decisions and can be repeated to track whether antivenom is working.
Antivenom is the only direct treatment for snake envenomation. It works by binding to venom molecules in your bloodstream and neutralizing them. The specific antivenom used depends on the snake species, which is why identifying the snake (or at least describing it) is so valuable. Treatment also includes managing symptoms: IV fluids for low blood pressure, mechanical breathing support for respiratory paralysis, and blood products for severe clotting problems.
Infection After the Bite
Snake mouths harbor a wide variety of bacteria, and secondary infection is a real risk even after the venom itself is treated. The most commonly identified bacteria from snake bite wounds are gram-negative species, which account for about 63% of infections. The leading culprit is a bacterium called Morganella morganii, found in roughly a third of infected cases, followed by Enterococcus species (23%) and Staphylococcus aureus (15%).
The tissue damage caused by venom creates an ideal environment for these bacteria to thrive. Dead or dying tissue has poor blood flow, which means your immune system and any antibiotics have difficulty reaching the infection. This is why snake bite wounds are carefully cleaned and monitored, and why some patients need surgical removal of dead tissue to prevent the infection from spreading.
Long-Term Effects of Envenomation
Most people assume that once you survive a snake bite and leave the hospital, you’re done. That’s not always the case. Some effects take months or even years to fully appear.
Kidney damage is one of the most significant long-term risks. In a study of 60 patients who needed dialysis after a snake bite, 40% still had impaired kidney function, protein in their urine, or high blood pressure nearly four years later. Three of those patients progressed to end-stage kidney disease requiring permanent dialysis. Another study found that 8 out of 100 patients who developed acute kidney injury from envenomation had chronic kidney failure six months after the bite.
Nerve damage can also linger. A study of 26 patients examined a year after a neurotoxic bite found abnormal nerve function in every single one, including slower nerve conduction speeds and delayed signal transmission. The practical effects vary from subtle numbness or tingling to more noticeable weakness in the affected limb.
Tissue destruction from cytotoxic venom can result in permanent disability. Amputations, chronic non-healing ulcers, scarring that limits joint movement, and deformities from deep tissue loss are all documented outcomes, particularly from cobra bites in Africa and Asia and pit viper bites in Central and South America. Globally, roughly three times as many people suffer amputations or permanent disabilities from snake bites as die from them.
Psychological effects are common and often overlooked. Depression, post-traumatic stress disorder, and ongoing physical complaints without a clear medical cause have all been reported in snakebite survivors. These effects frequently have a delayed onset, appearing weeks or months after the bite itself.
What to Do if You’re Bitten
Call emergency services immediately. While you wait, move away from the snake so you aren’t bitten again. Stay as still and calm as possible, since movement increases the speed at which venom circulates through your body. Remove rings, watches, and tight clothing before swelling starts, because once swelling sets in these items can cut off circulation. Position yourself so the bite is at a neutral, comfortable level. Clean the wound with soap and water and cover it loosely with a clean bandage.
Several popular “treatments” actually make things worse. Do not apply a tourniquet. Do not cut the bite or try to suck out the venom. Do not apply ice. Do not take aspirin, ibuprofen, or naproxen, all of which thin your blood and can worsen bleeding from hemotoxic venom. Avoid caffeine and alcohol.
If you can safely photograph the snake or remember its color, pattern, and size, that information helps medical teams choose the right antivenom. But never chase or handle the snake to identify it.
The Global Picture
Snake bites are far more common than most people realize. An estimated 5.4 million people are bitten by snakes every year worldwide, with 1.8 to 2.7 million of those involving actual envenomation. Between 81,000 and 138,000 people die annually, and the true toll is likely higher since many deaths in rural areas go unreported. India bears the heaviest burden of any single country: an estimated 58,000 Indians died per year from snakebite between 2000 and 2019.
The snakes responsible for the most human harm vary by region. In Latin America, lance-headed vipers of the genus Bothrops cause the majority of deaths and disabilities. In South and Southeast Asia, Russell’s vipers and kraits are the primary threats. Sub-Saharan Africa contends with puff adders, carpet vipers, mambas, and cobras. In Australia, brown snakes account for more than half of all snakebite deaths, while in Papua New Guinea the Papuan taipan is the leading killer. In the United States and Mexico, rattlesnakes are the most common culprit.