The short answer
A millipede cannot bite you. It has no venom, no sting and no fangs, and it has no interest in you whatsoever. On that much the reassuring version of this question is right.
What it does have is a defensive secretion, and there the reassuring version goes wrong. In an eye that secretion is a chemical burn that needs treating, and the published case series is mostly small children. One habit removes almost the entire risk: wash your hands with soap after handling, before you touch your face.
Almost everything frightening about millipedes is about centipedes
This is the single biggest source of confusion, so it is worth settling first.
A millipede carries two pairs of legs on each body segment, moves slowly, has a rounded body, eats decaying leaves and wood, and coils into a spiral when it is frightened. A centipede carries one pair per segment, is flattened and fast, hunts living prey, and has a venomous bite that hurts a great deal.
If the animal is slow, round in cross-section and rolls itself into a coil when you touch it, it is a millipede and it cannot bite you. Nearly every alarming story attached to the word millipede belongs to the other animal.
Why they cannot bite
Their mouthparts evolved to process material that is already soft: rotting leaves, decaying wood, the litter layer of a forest floor. They are blunt grinding structures with no cutting edge and no biting force, and there is no venom apparatus anywhere on the animal.
A frightened millipede has exactly two responses available. It coils to protect its soft underside, and it secretes. There is nothing else in the repertoire, which is why the secretion matters so much more than people expect.
What the secretion actually is
Defensive glands called ozopores release fluid when the animal is stressed, and in most millipedes they run along both sides of the body. Two chemical families turn up in most of the species kept as pets, and a third in the pill millipedes analysed so far.
Benzoquinones, produced by most of the large tropical millipedes in the hobby. Wood analysed the giant African millipede Archispirostreptus gigas directly in 1974 and identified toluquinone and 2-methoxy-3-methylbenzoquinone. These are the compounds behind the yellow-brown staining, the smell, and the eye injuries below.
Hydrogen cyanide, produced by many flat-backed millipedes in the order Polydesmida. The quantities are tiny and aimed at ants, not at anything your size, so the practical rule is simply not to seal a polydesmid into an unventilated container. It is a ventilation question, not a poisoning question.
Alkaloids, produced by the pill millipedes of the order Glomerida. Their glands open along the middle of the back rather than the sides, and the secretion is sticky. In Glomeris marginata it carries two quinazolinone alkaloids, glomerin and homoglomerin, which in tests sedated wolf spiders and made toads vomit, and a 2024 paper reports one or both in every species of the order analysed so far, all of them European or North American. We have found no study of what the secretion does to people, and our pill millipede care guide covers handling them.
The eye injuries are documented, and they are not trivial
Hudson and Parsons published eight ocular cases in 1997 involving a Spirobolida millipede. Every one of the eight had periorbital chemical burns. Three had swelling, two had conjunctivitis, one had keratitis, and all eight needed topical ophthalmic treatment.
Two things follow, and they pull in opposite directions.
The first is that this is a real injury with a real clinical description, not a sting that waters your eye for a minute. Any page telling you the secretion is mild or harmless has not read the case series.
The second is that every one of those eight patients recovered fully with standard eye treatment. The authors note the anecdotal reports that blindness is a likely result of a millipede burn to the eye, and record that it did not happen in their series. Medical references still list blindness as a rare possible outcome, and a 1975 paper on millipede burns warns that eye injuries can be serious and need effective treatment quickly to prevent lasting damage. So the fair summary is a chemical burn that needs treating promptly.
Seven of the eight were children of seven and under
That is the detail that changes how this question should be answered, and it is missing from almost every page that addresses millipede safety, including the earlier version of this one.
A small child handles the animal, does not notice the faint residue, and rubs an eye a few minutes later. Adults do the same thing, but adults wash their hands more reliably and rub their eyes less. So millipedes are excellent animals for children to watch and to learn from, under supervision, and the supervision is specifically about hands and eyes, not about the animal biting, which it cannot do.
On skin it is usually a stain, and sometimes a burn
The yellow-brown mark that appears on your fingers is the usual result. It can last days to weeks and resists washing, so wash the secretion off promptly with soap and water rather than leaving it on the skin. Some people get redness or an itch, and anyone finding that happens repeatedly should use gloves or handle less.
A large tropical millipede can do more than stain, with burning, blistering and swelling all on record, and a clinical review puts most skin irritation and staining at several days to a month. On hands it is a nuisance; in an eye it is not. The secretion is a deterrent aimed at ants and small vertebrates, not a venom.
The secretion tells you something about the animal
A millipede that secretes is frightened, and producing those compounds costs it real energy. One that is handled until it secretes, repeatedly, is being drained for no reason.
So treat these as animals you watch and occasionally handle, not animals you handle and occasionally watch. A settled millipede walking across a palm will not secrete at all. If yours does, put it back.
Two more rules that exist for the animal, not for you. Never handle one that is about to moult or has just moulted, because the new exoskeleton is soft and the animal is extremely fragile. And always handle low over a soft surface, since a fall from even a modest height can crack the shell and kill it.
Dogs, cats and other pets
An animal that mouths a millipede usually drops it at once, because the secretion tastes foul and that is exactly its function. Some drool or are sick afterwards. It is unpleasant rather than dangerous, and the sensible answer is the one you would reach anyway: keep the enclosure secure and out of reach.
Common questions
Are millipedes dangerous to humans?
They cannot bite, sting or envenomate. The injuries on record come from the defensive secretion: a chemical burn in an eye, which needs medical treatment, and staining or, from large tropical species, burns on skin. Washing your hands with soap straight after handling prevents most of it.
Do millipedes bite?
No. The mouthparts are blunt grinders for rotting leaves and cannot break skin. An invertebrate that bit you was not a millipede.
Are millipedes poisonous?
Not in the sense people mean. Most of the large tropical species secrete benzoquinones, and the pill millipedes analysed so far carry alkaloids instead; some flat-backed species release trace hydrogen cyanide, far too little to poison a person. The benzoquinone secretion stains and irritates skin, can burn it in the large tropical species, and burns an eye; we have found no study of what the pill millipedes' secretion does to people. Beyond that, medical references say nausea and vomiting may occur after contact with a large number of millipedes.
What do I do if secretion gets in an eye?
Irrigate with plenty of clean water and get it looked at. All eight of Hudson and Parsons' patients needed topical ophthalmic treatment, so this is a see-someone situation and not a wait-and-see one.
Can millipedes blind you?
It is possible but rare, according to medical references, so rinse any secretion out of an eye and get it looked at promptly. We found no published case report of blindness from a millipede, and all eight of Hudson and Parsons' patients recovered fully with standard eye treatment.
Are millipedes safe for children?
They are good animals for children, with supervision aimed at the right thing. A millipede cannot hurt a child directly. What it can do is leave secretion on small fingers that go to an eye. Seven of the eight patients in a published series of eye cases were children of seven and under. Supervise the hand-washing and the outcome is fine.
Can I hold my millipede?
Yes, gently, briefly and low over something soft. Treat it as occasional. If the animal secretes it is telling you it wants to be put down.
In summary
Millipedes are among the safest large invertebrates anyone can keep, and the reasons people fear them are mostly borrowed from centipedes. The one real risk is chemical. It is worst in the eyes, where it is documented in a small clinical series whose patients were mostly young children, and the large tropical species can burn skin as well as stain it.
Wash your hands with soap after handling. That single habit is most of millipede safety.
New to these animals? The beginner millipedes guide covers which species to choose, the giant African millipede guide covers the classic one, and the substrate guide covers what they live in. The full range sits under millipedes for sale, where the African Giant Black and Ghana Speckled Leg listings say plainly that their animals are wild-caught, because across the millipede trade a great deal of it still is.
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