Do Garter Snakes Bite and Are They Dangerous?

Garter snakes do bite, but they pose almost no danger to people. These small, widespread snakes across North America would rather flee than fight, and their bites typically produce nothing worse than minor scratching and a little bleeding. What surprises most people is that garter snakes are not entirely “non-venomous” in the textbook sense: they produce a mild toxic secretion from glands in their heads, though the delivery system is so inefficient that medically significant reactions in humans are rare and limited to local swelling.

When and Why Garter Snakes Bite

A garter snake’s first instinct when threatened is to get away. If it can’t escape, it cycles through a menu of defensive behaviors before resorting to biting. Research on eastern garter snakes found that body temperature strongly influences which defense a snake chooses. Warmer snakes fled more often than cold ones, and when warm snakes couldn’t flee, they were more likely to gape their mouths or bite. Colder snakes, constrained by sluggish muscles, tended to flatten their bodies as a bluff instead.

1PubMed. Thermal influence on defensive behaviours of the Eastern garter snake, Thamnophis sirtalis

In practical terms, you’re most likely to be bitten if you grab or pin a garter snake, particularly on a warm day when it has the metabolic energy to strike. A snake sunning itself on a rock in July is quicker to snap than one you uncover beneath a board in early spring. Even then, most garter snakes try several other tactics before biting: fleeing, coiling into a ball, flattening the head and body to look bigger, gaping the mouth as a warning, or thrashing wildly.

Individual temperament matters too. Studies on newborn plains garter snakes showed that defensive behavior varies considerably between individuals even within the same litter, but each snake’s personality stays consistent across repeated encounters with threats. These behavioral differences are partly heritable, with heritability estimates around 0.37 to 0.45, meaning some garter snakes are simply born bolder or more defensive than others.

2Elsevier / ScienceDirect (Animal Behaviour). Behavioural variation in natural populations. III: Antipredator displays in the garter snake Thamnophis radix

What a Bite Feels Like

Garter snakes are small, and their teeth are proportionally tiny. A bite from a typical garter snake feels like a sharp pinch or a scratch from a thorn. You might see a few pinprick marks or a thin line of scratches where the teeth dragged, and a small amount of bleeding. The teeth are not designed to puncture deeply into large prey the way a pit viper’s fangs are. Instead, garter snake teeth are adapted for gripping slippery food like worms, frogs, and fish.

Tooth shape varies across garter snake species depending on diet. Fish-eating species like the Sierra garter snake have longer, sharper teeth and elongated jaw bones suited for snagging fast-moving prey. Species that eat slugs and snails have ridged rear teeth that help grip soft-bodied prey. A generalist feeder’s teeth tend to be shorter and less specialized.

3Journal of Herpetology. Dental Morphologies in Gartersnakes (Thamnophis) and Their Connection to Dietary Preferences

For the person on the receiving end, these differences are mostly academic. No garter snake species has teeth large enough to cause a significant wound in a human. The primary discomfort comes from the surprise of being bitten and the slight stinging of broken skin.

The Musking Problem

Biting is actually one of the less unpleasant things a garter snake can do to you. When handled, garter snakes frequently release a foul-smelling musk from glands at the base of the tail, often mixed with feces. This secretion is widely recognized as one of their primary defensive tactics, though researchers note that it has been studied less quantitatively than other antipredator behaviors.

4Journal of North American Herpetology. EFFECTS OF SEX, ENVIRONMENT, AND CONDITION ON THE MUSKING BEHAVIOR OF SYMPATRIC GARTERSNAKES (THAMNOPHIS SPP.)

The smell is genuinely bad and clings to skin and clothing. If you’ve ever picked up a garter snake and had it smear a yellowish, pungent substance on your hands, that was musk, not venom. Many people who handle garter snakes regularly consider the musk far more objectionable than the bite itself. It washes off with soap and water, but the memory lingers.

Garter Snakes Actually Produce Venom

For most of the twentieth century, garter snakes were classified as completely harmless and non-venomous. That picture has changed. Garter snakes possess a structure called Duvernoy’s gland, located behind the eye, which produces a toxic secretion. This gland is not the same as the venom glands found in rattlesnakes or cobras, and the difference matters. In true venomous snakes, a large reservoir stores venom, and specialized fangs inject it under pressure when the snake strikes. Garter snakes have neither the reservoir nor the delivery fangs.

In the common garter snake, Duvernoy’s gland has no direct mechanical connection to the jaw muscles. Instead, when the snake chews on prey, the contraction of nearby muscles squeezes the gland and pushes secretion toward the rear teeth.

5PubMed. The mechanism of venom secretion from Duvernoy’s gland of the snake Thamnophis sirtalis The gland itself lacks the large storage lumen found in true venom glands, so the amount of secretion released during any single bite is small.

6PubMed. Ultrastructure of duvernoy’s gland from the wandering garter snake, Thamnophis elegans vagrans (Serpentes, Colubridae)

This means the secretion works best during prolonged chewing on small prey, not during the quick defensive snap a human would receive. The system is geared for subduing frogs and fish, not for self-defense against large predators. A quick defensive bite delivers very little of the secretion, if any at all.

What the Venom Actually Contains

Despite the inefficient delivery system, the secretion itself is more potent than you might expect. In lab tests, the Duvernoy’s secretion from the wandering garter snake proved highly toxic to mice, causing severe hemorrhaging in the lungs, diaphragm, and digestive lining.

7Toxicon. The toxic Duvernoy’s secretion of the wandering garter snake, Thamnophis elegans vagrans Other oral secretions from the same snake, collected separately from Duvernoy’s gland output, did not produce lethal effects even at seven times the dose. So the toxicity is specifically tied to the Duvernoy’s gland product, not just general “snake saliva.”

Transcriptomic studies of the common garter snake’s Duvernoy’s gland have identified four major families of toxin genes. The secretion contains a roughly even split between components that affect the nervous system and components that break down tissue, at about 30% each. That balance is unusual among rear-fanged snakes studied so far; most lean heavily toward one category or the other.

8PubMed. Thamnophis sirtalis and their toxic relationship: Testing for intraspecific venom variation in Common Garter Snakes

The composition also varies by sex and body size, with differences in toxin gene expression between males and females as the animals grow. This kind of intraspecific variation in venom is well documented in many snake lineages, but its discovery in garter snakes is relatively recent and underscores that these animals are more biochemically complex than their harmless reputation suggests.

Can a Garter Snake Bite Actually Hurt a Person?

In rare cases, yes, though “hurt” here means localized swelling and bruising, not a life-threatening emergency. The medical literature contains a handful of documented human envenomations from garter snakes, and they share a common pattern: the bite was prolonged, lasting many seconds or even minutes while the snake chewed, allowing enough secretion to enter the wound to cause symptoms.

In one case, a person bitten on the fingertip by a wandering garter snake quickly developed swelling, bruising, and fluid-filled blisters at the bite site. No bodywide symptoms developed.

9Annals of Emergency Medicine. Human envenomation from a wandering garter snake Another report from the same subspecies described swelling, pain, and localized bleeding after a prolonged bite, again with no systemic effects.

10PubMed. Envenomation following the bite of a wandering garter snake (Thamnophis elegans vagrans) A third case involved a 13-year-old bitten by an eastern garter snake; the child developed a cool, swollen, and bruised hand with some involvement of the lymph system, but vital signs and blood tests were normal, and recovery was rapid.

11Toxicon. Human envenomation from the bite of the eastern garter snake, Thamnophis s. sirtalis (Serpentes: Colubridae)

The common thread across all published cases is that the person let the snake chew for an unusually long time. A quick defensive nip, the kind you’d get from accidentally stepping near a garter snake or reaching into a garden where one is hiding, is extremely unlikely to introduce enough secretion to cause anything beyond minor scratching. The handful of documented envenomations tend to involve people who were handling the snake, often deliberately, and allowed it to maintain its grip.

Infection Risk from Bacteria

A more realistic concern from a garter snake bite than venom is infection. A study of garter snake oral bacteria found 126 strains of aerobic bacteria from 82 oropharyngeal cultures, most of which were potential pathogens for both snakes and humans. The researchers identified species including Pseudomonas, Klebsiella, Salmonella, and Shigella in garter snake mouths, and recommended that pet owners and lab workers treat the snakes as reservoirs of human pathogens.

12PubMed Central. Aerobic bacterial oral flora of garter snakes: development of normal flora and pathogenic potential for snakes and humans

This doesn’t mean every garter snake bite will get infected. The wounds are small and superficial, and basic wound care handles the risk. But if you are bitten, wash the area with soap and warm water, apply a simple antibiotic ointment, and watch for signs of infection over the next few days: increasing redness, warmth, swelling, or pus. Anyone who develops these signs should see a doctor, not because of the snake’s venom but because of ordinary bacterial wound infection.

What to Do If You’re Bitten

A garter snake bite does not require emergency medical treatment in the vast majority of cases. Wash the bite site thoroughly, apply a bandage if it’s bleeding, and leave it alone. Do not apply a tourniquet, try to suck out venom, or cut the wound open. These outdated first-aid myths are harmful for any snakebite, regardless of species.

General snakebite first-aid guidelines recommend staying calm, removing tight jewelry or clothing near the bite in case of swelling, immobilizing the affected limb, and contacting medical services if you’re unsure of the species or if symptoms worsen.

13PLOS Neglected Tropical Diseases. The Treatment of Snake Bites in a First Aid Setting: A Systematic Review For a confirmed garter snake bite, the “contact emergency services” step is almost never necessary. The exception would be if the snake chewed for an extended period and you notice significant swelling, bruising, or blistering, in which case a visit to an urgent care clinic or emergency room is reasonable as a precaution.

There is no antivenom for garter snake bites, nor is one needed. The documented human cases resolved on their own with basic supportive care.

Why Venom in a “Harmless” Snake?

The venom isn’t for you. Garter snakes use their Duvernoy’s gland secretion to help subdue and digest prey. Research across multiple garter snake species has found a strong relationship between the complexity of a species’ diet and the complexity of its toxin expression. Species that eat a wider variety of prey tend to express a greater diversity of toxin gene families in their Duvernoy’s glands.

14Oxford Academic. Dietary Breadth Predicts Toxin Expression Complexity in the Venoms of North American Gartersnakes

Total toxin expression varies enormously across garter snake species, from less than 1% of total gland output to over 70%. A specialist that eats mostly earthworms may barely produce any toxin, while a generalist that eats fish, frogs, salamanders, and invertebrates may invest heavily in a diverse chemical arsenal. The venom, in other words, is a foraging tool, shaped by what the snake eats rather than by what might eat the snake.

The Tetrodotoxin Arms Race

One of the most celebrated stories in evolutionary biology involves garter snakes and their toxic prey. In parts of the Pacific Northwest, common garter snakes eat rough-skinned newts, which are loaded with tetrodotoxin, a powerful neurotoxin that blocks nerve signals. A single newt carries enough toxin to kill most predators many times over. But certain populations of garter snakes have evolved remarkable resistance to it.

15PubMed. TETRODOTOXIN RESISTANCE IN GARTER SNAKES: AN EVOLUTIONARY RESPONSE OF PREDATORS TO DANGEROUS PREY

The resistance traces largely to mutations in a gene coding for a sodium channel protein in skeletal muscle. Variation in this gene explains a large fraction of the variation in tetrodotoxin resistance between individual snakes.

16PubMed Central. Genetic architecture of a feeding adaptation: garter snake (Thamnophis) resistance to tetrodotoxin bearing prey But the story doesn’t stop at one gene. Researchers have found parallel resistance mutations in multiple sodium channel genes across different tissues, including nerves. Some of these mutations are expected to confer high resistance, protecting nerve function in snakes that regularly swallow one of the most toxic animals on the planet.

17PubMed Central. Parallel Evolution of Tetrodotoxin Resistance in Three Voltage-Gated Sodium Channel Genes in the Garter Snake Thamnophis sirtalis

The populations of garter snakes that coexist with toxic newts have dramatically higher resistance than populations from areas where newts don’t occur. This geographic pattern is strong evidence for an evolutionary arms race: newts evolve to be more toxic, snakes evolve to tolerate the toxin, and the cycle continues. Garter snake populations without toxic newts in their range show no such resistance, confirming that the trait evolved specifically in response to the prey.

This has nothing to do with whether a garter snake bite is dangerous to you, but it illustrates just how biochemically sophisticated these animals are beneath their reputation as garden-variety backyard snakes. An animal capable of surviving a neurotoxin that would kill a human many times over is not as simple as it looks.

Keeping Garter Snakes as Pets

Garter snakes are among the most commonly kept pet snakes in North America, partly because of their small size, simple care requirements, and general docility. Captive-bred garter snakes are typically less defensive than wild-caught ones and rarely bite once accustomed to handling. Wild-caught snakes are more likely to musk, thrash, and bite when first picked up, though most calm down with regular gentle handling over a period of weeks.

If you keep a garter snake as a pet, the bite risk is minimal but not zero, especially during feeding time when the snake may mistake your fingers for food. Using tongs to offer prey items rather than dropping food in by hand reduces this possibility. Pet garter snakes that do bite during feeding usually let go immediately once they realize the target is not a worm or fish.

The oral bacteria concern described earlier is worth keeping in mind for pet owners. Washing your hands after handling the snake or cleaning its enclosure is good practice, not because of venom but because of the Salmonella and other bacteria that reptiles commonly carry in their mouths and digestive tracts. This applies to all pet reptiles, not just garter snakes.