Millipedes don’t bite. They lack the mouthparts to pierce human skin, and when threatened, their only defense is to curl into a ball or release a chemical fluid from glands along their body. If you found a many-legged creature in your house and got bitten, you’re almost certainly dealing with a house centipede, not a millipede. The two are commonly confused, but the distinction matters because they cause very different types of skin reactions.
Millipedes vs. House Centipedes
Millipedes are slow-moving, cylindrical creatures with two or four pairs of tiny legs per body segment. They eat decaying plant material and pose no biting threat to people. House centipedes are flattened, fast-moving predators with one pair of legs per segment and long legs that trail behind their body. Centipedes hunt other insects and can bite when provoked.
The quickest way to tell them apart: if it moved fast and had long, spindly legs, it was a centipede. If it was slow, rounded, and curled up when you touched it, it was a millipede. Both are attracted to damp indoor spaces like basements, bathrooms, and crawl spaces, which is why either one might show up in your home.
What Millipedes Actually Do to Your Skin
Instead of biting, some millipede species secrete a defensive liquid called benzoquinone from glands along each body segment. A few species can even spray this fluid several feet. On human skin, benzoquinone acts as a chemical irritant rather than a venom. It causes localized pigment changes that can look dark red, blue, or black, often resembling a burn, which is why the medical term is “millipede burn.”
The severity depends on how long the fluid stays on your skin. Brief contact might cause mild redness or itching. Prolonged contact can produce blisters, a burning sensation, or skin that looks necrotic (darkened and damaged). The most common sites are the feet and toes, since people often step on millipedes barefoot, followed by the arms, face, and eyes. These discolored patches resolve on their own over time without lasting damage.
The fluid also contains traces of hydrochloric acid and hydrogen cyanide, but in quantities far too small to cause poisoning in humans. The real risk is getting it in your eyes, where it can cause conjunctivitis and significant irritation. If you’ve handled a millipede, avoid touching your face until you’ve washed your hands.
Allergic Reactions to Millipede Secretions
Some people are allergic to millipede fluid. Mild allergic reactions include blisters, skin redness, rash, and itching or burning beyond the contact area. In rare cases, a more serious allergic response can develop, with facial swelling, difficulty breathing, rapid heartbeat, or a widespread rash. These symptoms need immediate medical attention.
House Centipede Bites
If you were actually bitten, a house centipede is the likely culprit. Centipedes use venom-injecting claws (called forcipules) near their head to subdue prey. On humans, a house centipede bite typically causes sharp, sudden pain at the site, followed by localized swelling, redness, and sometimes numbness or tingling. Most people describe it as similar to a bee sting.
The pain and swelling from a house centipede bite are self-limiting, usually resolving within a few hours to a few days. You might also notice a small puncture mark, mild bruising, or a burning sensation around the bite. Less commonly, small blisters can form at the site. Some people experience mild secondary symptoms like headache, anxiety, slight dizziness, or general achiness, but these pass quickly.
Systemic allergic reactions to centipede bites are rare but documented. In one case, a child developed widespread hives, facial swelling, and breathing difficulty within about 10 minutes of being bitten. These severe reactions can occur at body sites far from the bite itself, which distinguishes them from normal local irritation.
First Aid for Each Situation
Millipede Fluid on Skin
Wash the area thoroughly with soap and water as soon as possible. The sooner you remove the secretion, the less skin discoloration you’ll get. Watch for blistering, broken skin, or signs of infection in the following days. Brown stains left on the skin will fade on their own without treatment.
If millipede fluid gets in your eyes, hold the eye open and rinse it under running water for 15 minutes. Then see a doctor or visit an emergency department for an eye exam as soon as you can.
Centipede Bite
Wash the bite gently with soap and water. Apply a cold, damp cloth or an ice pack wrapped in fabric for 10 to 20 minutes to bring down swelling and pain. If the bite is on your arm or leg, elevating the limb helps reduce swelling. Over-the-counter hydrocortisone cream or calamine lotion applied several times a day can ease itching, and an oral antihistamine can help if the irritation spreads. A standard pain reliever can manage discomfort.
Watch the bite over the next couple of days. If swelling worsens, the area becomes hot or streaked with red, or you develop a fever, those are signs of possible infection that need medical evaluation.
Keeping Them Out of Your Home
Both millipedes and centipedes enter homes seeking moisture. Reducing dampness is the single most effective way to discourage them. Run a dehumidifier in your basement, fix leaky pipes, and make sure bathrooms and attics have adequate ventilation. Clear clutter from these areas to eliminate hiding spots.
Seal entry points by repairing torn window screens, adding weather stripping to doors, and caulking gaps around pipes and utility lines where they enter the foundation. Outdoors, move mulch, leaf litter, and firewood away from your home’s perimeter, since these materials create the damp habitat both creatures prefer. If you consistently find them indoors, a perimeter insecticide applied around door frames, window casings, and baseboards can create a barrier that reduces how many make it inside.