No, the Komodo dragon is not poisonous, it is venomous. In 2009, scientists found venom glands in its lower jaw. Its venom stops blood clotting and lowers blood pressure, sending prey into shock. The old idea that bacteria in its mouth kill prey has been rejected. Komodo dragons bite, then pull back to rip deep cuts that let the venom in.
whether Komodo dragons are poisonous quick facts
- Komodo dragons are venomous, not poisonous.
- Their venom glands were discovered in 2009.
- The venom stops blood clotting and lowers blood pressure.
- Their bite is about six and a half times weaker than a crocodile’s.
- Komodo dragons have been listed as Endangered since 2021.
Is the Komodo dragon poisonous?
Strictly speaking, no. The Komodo dragon is not poisonous, it is venomous. That might sound like the same thing, but it is not.
A poisonous animal is harmful if you touch it or eat it. A venomous animal puts venom into another animal, usually by biting or stinging. Komodo dragons are venomous because they have venom glands in their jaws and deliver venom through their bite.
This was proved in 2009 by a team of scientists led by Dr Bryan Fry of the University of Melbourne in Australia. Before that, most people believed something quite different about how Komodo dragons kill.
| Komodo dragon at a glance | |
|---|---|
| Poisonous? | no |
| Venomous? | yes, with venom glands in the lower jaw |
| What the venom does | stops blood clotting and lowers blood pressure |
| Teeth | about 60, serrated like a shark’s |
| Length | males usually 1.8 to 3 m |
| Home | a few islands in south-east Indonesia |
| Status | Endangered |
The venom discovery
In 2009, Bryan Fry’s team published their work in the journal Proceedings of the National Academy of Sciences. The University of Melbourne says they used an MRI scanner, a machine that sees inside things, to look inside a preserved Komodo dragon’s head.
They found complex venom glands and special serrated teeth. The study says each venom gland sits in the lower jaw, with one large section at the back and five smaller sections at the front. Each section has a tiny tube, called a duct, that opens between the teeth.
National Geographic reported that this is the most complex venom duct system yet described in any reptile. National Geographic says snakes, by comparison, have just one duct for each gland.
The study found that the venom glands of a 1.6 m Komodo dragon held about 1 ml of venom, about a fifth of a teaspoon. To study the venom itself, the University of Melbourne says, scientists removed the glands from a terminally ill dragon at Singapore Zoo.
What does the venom do?
Komodo dragon venom works on the blood. The 2009 study says it stops blood from clotting, makes blood pressure drop, and can send the prey into shock.
National Geographic says the venom lowers blood pressure, causes massive bleeding and stops clotting. The study says some toxins may also cause painful cramps that stop the prey from moving properly.
So when a Komodo dragon bites a deer and it runs off, the venom keeps working. The weakened animal can be followed and found later.
The old dirty mouth idea
For many years, people believed Komodo dragons killed with germs. The University of Melbourne says the popular idea was that prey died from blood poisoning caused by harmful bacteria in the dragon’s mouth.
The 2009 researchers rejected that idea. They said there is no strong evidence that bacteria play a part in how Komodo dragons kill. National Geographic reported that Bryan Fry called the bacteria story “a scientific fairy tale”.
Komodo dragons do eat rotting meat, and their bodies are good at coping with it. San Diego Zoo Wildlife Alliance’s library says their blood contains natural protection against many types of bacteria.
You may still read the old bacteria idea in some places, even on some zoo websites. But the venom research shows the real story.
Grip and rip
Komodo dragons have fearsome teeth. San Diego Zoo Wildlife Alliance says they have about 60 short, serrated teeth, like a shark’s. The library says the longest are about 2 cm long, and four or five replacement teeth wait behind each one.
In 2024, scientists at King’s College London found that the tips and serrated edges of Komodo dragon teeth are coated in iron. The iron stains them orange and helps keep them sharp.
Surprisingly, their bite is quite weak. The 2009 study measured it at about 39 newtons, around six and a half times weaker than the bite of a saltwater crocodile of a similar size.
Instead of crushing, a Komodo dragon bites and then pulls back hard with its whole body, ripping deep cuts that let the venom in. Scientists call this “grip and rip”.
Are Komodo dragons dangerous to people?
Komodo dragons can be dangerous. National Geographic reported in 2014 that attacks on people are not common, but a few have made the news.
In 2013, National Geographic says, a Komodo dragon about 2 m long walked into a ranger office on the island of Rinca and bit two rangers on the leg. Both were flown to hospital in Bali and recovered.
In another case, an 83-year-old woman fought off a dragon with a broom and kicks, and her bitten hand needed 35 stitches. Sadly, in 2007 a boy from a village in Komodo National Park died after a dragon attack.
National Geographic says that when a dragon comes close to homes or farm animals, villagers usually shout and throw rocks. The government has moved dragons that attack people away from villages, but they usually come back.
Meet the Komodo dragon
The Komodo dragon is a type of monitor lizard, named after Komodo Island in Indonesia. National Geographic says it is the heaviest lizard on Earth. Find out much more in our Komodo dragon facts.
San Diego Zoo Wildlife Alliance says males are usually 1.8 to 3 m long and weigh 70 to 136 kg. Females are smaller, up to about 2.5 m long.
Their skin is armoured with tiny bones called osteoderms, the library says. Young dragons have bright, speckled skin until about four years old, while most adults are plain grey or clay-coloured.
Komodo dragons have an ancient history. The library says they evolved about 4 million years ago and once lived across mainland Australia. The University of Melbourne says an extinct giant relative called Megalania was about 7 m long and probably had a similar venom system, making it the largest venomous animal that ever lived.
Where do Komodo dragons live?
Komodo dragons live only on a few islands in south-east Indonesia, including Komodo, Rinca and Flores. San Diego Zoo Wildlife Alliance says their whole range covers less than 900 km².
Their islands are rugged and hilly, with forest and grassy savanna. San Diego Zoo Wildlife Alliance says daytime temperatures can reach 35 °C.
Hunting and eating
Komodo dragons are powerful hunters. San Diego Zoo Wildlife Alliance says adults eat Timor deer, water buffalo, wild pigs, snakes and fish, while young dragons eat eggs, grasshoppers, beetles and geckos.
They flick their long, yellow, forked tongues to pick up smells, the library says. They can eat enormous meals: the library says a 50 kg female was seen swallowing a 31 kg wild boar in just 17 minutes.
Big Komodo dragons kill about one large deer or boar a month, the library says. Large dragons sometimes even eat smaller Komodo dragons.
Eggs and young dragons
A female lays about 20 to 30 eggs, each about the size of a grapefruit, San Diego Zoo Wildlife Alliance says. The library says baby dragons live in trees for their first year, to stay safe from predators, including bigger dragons.
The library says female Komodo dragons can sometimes lay eggs that hatch without a father. This is called a virgin birth, and the babies are always male.
Komodo dragons are grown up at five to seven years old, and live up to about 30 years in the wild, San Diego Zoo Wildlife Alliance says.
Komodo dragons in danger
Komodo dragons are now endangered. The IUCN World Heritage Outlook says they moved from Vulnerable to Endangered on the IUCN Red List in 2021, and there are fewer than 1,400 adults in the wild.
Counting young dragons too, San Diego Zoo Wildlife Alliance says there are about 3,500, down from about 5,000 in 1981.
Komodo National Park, set up in 1980, is their main stronghold. The IUCN says the park counted 3,396 dragons in 2023, up from 2,897 in 2018.
San Diego Zoo Wildlife Alliance warns that rising sea levels could wipe out 30 to 70% of the places Komodo dragons live by 2040. They are also threatened by habitat loss, illegal trade, feral dogs and the poaching of the deer and pigs they eat. As top predators, they are an important part of their ecosystem.
Three things people get wrong
Komodo dragons do not kill with dirty spit. They use venom from glands in their jaws.
Komodo dragons do not have a crushing bite. Their bite is weaker than a crocodile’s; they grip and rip.
Komodo dragons are not poisonous. They are venomous: they inject venom through a bite.
Did you know? The tips of a Komodo dragon’s teeth are coated in iron, which stains them orange and helps keep them sharp.
Try it
Make a two-column list: animals that are venomous, like Komodo dragons, and animals that are poisonous. What is the difference?
Knowledge check
What is the difference between venomous and poisonous?
Show answer
Venom is injected by a bite or sting; poison harms you if touched or eaten.
Where are a Komodo dragon’s venom glands?
Show answer
In its lower jaw.
Frequently asked questions
Is the Komodo dragon poisonous or venomous?
It is venomous. It has venom glands in its lower jaw and delivers venom through its bite. It is not harmful to touch.
What does Komodo dragon venom do?
It stops blood from clotting, lowers blood pressure and can send prey into shock, causing heavy bleeding.
Do Komodo dragons kill with bacteria?
No. That old idea was rejected by a 2009 study, which found venom glands and no strong evidence that bacteria help them kill.
Can a Komodo dragon hurt a human?
Yes. Attacks are not common, but they can be serious, and at least one child has died after an attack.
How strong is a Komodo dragon’s bite?
Quite weak, about 39 newtons. It relies on sharp, serrated teeth, pulling back hard and venom instead of crushing.
Are Komodo dragons endangered?
Yes. They were listed as Endangered in 2021, with fewer than 1,400 adults in the wild.
Sources
- University of Melbourne news release (via ScienceDaily): Komodo dragon venom (2009) — the MRI study, the venom, the bacteria idea and Megalania
- Proceedings of the National Academy of Sciences (Fry et al. 2009), via PubMed Central — the venom glands, venom effects, bite force and grip-and-rip feeding
- National Geographic: Komodo dragon venom (2009) — the duct system, venom effects and the fairy tale quote; its Komodo dragon facts page and 2014 magazine article on attacks were also used
- San Diego Zoo Wildlife Alliance: Komodo dragon — size, teeth, islands, diet, eggs and threats; its library fact sheets were also used
- King’s College London: iron-coated teeth (2024) — the iron coating on Komodo dragon teeth
- IUCN World Heritage Outlook: Komodo National Park — status, population and dragon counts in the park
