10 Deadliest Poisons Known to Man

The ten deadliest poisons

ThoughtCo / Hilary Allison

A poison is a substance that causes death or injury when it's ingested, inhaled, or absorbed into the body. Technically, anything can be a poison. If you drink enough water, you'll die. It's just a matter of dose. So, this list covers poisons that are lethal at extremely low doses. Why would anyone need such a list? It may be helpful if you're writing a murder mystery or wondering whether someone is out to get you. Maybe you're just curious...

Key Takeaways: 10 Deadliest Poisons

  • The deadliest poisons in the world include chemical weapons; natural compounds; chemical defenses used by plants, animals, fungi, and bacteria; and even chemical elements.
  • Most of the truly deadly poisons are neurotoxins. Death usually occurs from suffocation when muscles become paralyzed and a person can't breathe.
  • Although all substances on this list are deadly, some are actually survivable with first aid or professional medical attention.


castor beans
Ricin is a potent toxin that comes from castor beans. Although castor oil also comes from beans, it doesn't contain the poison. Kazakov / Getty Images

Ricin is a deadly poison that comes from castor beans. A dose the size of a single grain of sand is enough to kill. The toxin works by inactivating ribosomes and halting protein production, which is ultimately a lethal problem. There's no antidote to the poison, although it's possible to survive if the dose is small enough.

Ricin was used to assassinate Bulgarian Georgi Markov in 1978. While it isn't likely you'll encounter the purified poison, the toxin is found in seeds of the castor plant. Swallowing the seeds whole won't poison you, but children and pets should be kept away from the interesting-looking beans because chewing them may release enough toxins to cause harm.

Botulinum Toxin (Botox)

A woman getting a Botox injection in her forehead
A Botox injection delivers a carefully controlled dose of the ordinarily deadly botulinum toxin. Adam Gault / Getty Images

The bacterium Clostridium botulinum produces a deadly neurotoxin called botulinum. If the bacteria are ingested, botulism poisoning may result. You can get this from improperly sealed cans or bad meat. Pain and temporary muscle paralysis is the best case scenario. Severe paralysis can stop a person from breathing, causing death.

The same toxin is found in Botox, where a tiny dose is injected to freeze muscles into place, minimizing wrinkles. Botox attacks neurotransmitters so that contracted muscles are unable to relax.


A puffer fish
Puffer fish aren't the only animals that contain the venom tetradotoxin. It's also found in some types of octopus, newts, toads, and worms. Jeff Rotman / Getty Images

Tetradotoxin or TTX is a powerful neurotoxin that shuts down nerve conduction between the brain and the body by blocking sodium channels. A minute dose can cause loss of sensation and paralysis, but just a tiny bit more paralyzes muscles you need working in order to live. It takes around 6 hours to reach full effect, but once the diaphragm stops, the lungs can no longer inhale or exhale and you're a goner. Or, you could die sooner from an irregular heartbeat.

How do you get exposed? The puffer fish is used to prepare the Japanese delicacy fugu. If the organs containing the toxin are damaged or incompletely removed, the dish is deadly. The puffer isn't the only animal that carries this toxin. It's also found in some octopuses, flatworms, sea stars, angelfish, toads, and newts. TTX is lethal whether it's inhaled, ingested, or absorbed directly into the bloodstream through a cut.


A poison dart frog
The toxin batrachotoxin actually comes from the food poison frogs eat, not the frogs themselves.

David Tipling / Getty Images

Of all the toxins on this list, batrachotoxin is the one you're least likely to encounter (unless you live in a tropical rain forest). The poison is found on the skin of poison dart frogs. The frogs themselves are not the source of the toxin. It comes from the food they eat. When you see these frogs in a zoo, rest assured they aren't eating deadly beetles, so they can't harm you.

The amount of the chemical depends on the species of frog. The golden poison frog from Columbia may carry enough toxin that touching it would expose you to enough batrachotoxin to kill around two dozen people.

The poison is a neurotoxin that interferes with sodium channel functioning. The result is paralysis and a quick death. There is no antidote.


Amanita muscaria
Fly agaric (Amanita muscaria) produces deadly amatoxin. The poisonous mushroom takes a few days to kill a person, damaging the liver, heart, and kidneys. Sven Zacek / Getty Images

Amatoxin is the deadly poison found in Amanita mushroom, such as the fly agaric. Eating one mushroom may be enough to end you, so it's not the very worst chemical on this list, but one you're more likely to encounter than some of the others (particularly if you know a cook you likes to pick wild mushrooms). Amatoxin attacks the kidneys and liver. Eventually, the damage leads to a coma and death. It's not a quick death.


Apple seeds
Apple seeds, cherry pits, and bitter almonds all contain cyanide. You'd have to eat a lot at once to get sick because your body can detoxify small amounts of the poison. Image Source / Getty Images

Cyanide is a deadly poison that binds to iron in blood, preventing it from carrying oxygen to cells. A lethal dose kills in minutes. However, this toxin is so common in nature that the body detoxifies small amounts. It's found in seeds of apples, cherries, almonds, and apricots. Hydrogen cyanide is a chemical weapon. It's said to smell like almonds, although the truth is, the odor of almonds is that of the cyanide they contain!

Nerve Gas

US Marines Train for Toxic Chemical Terrorism.
US Marines Train for Toxic Chemical Terrorism. While nerve gas is deadly, exposure can be survivable in some cases. Leif Skoogfors / Getty Images

Any one of the nerve agents could be on the list of deadliest chemicals. Sarin, VX, and related compounds are far more deadly than most of the other compounds. Sarin, for example, is about 500 times more toxic than hydrogen cyanide.

Nerve gas does not need to be inhaled to be effective. It can be absorbed through skin. While it's possible to survive an extremely low dose, the victim usually suffers some level of permanent neurological damage. VX may be even more powerful, although the nerve agent was never used in battle, so there is less data on it. VX inhibits an enzyme in the nervous system so that it constantly fires signals. Loss of control of bodily functions, suffocation, and convulsions lead to death.


Pest control chemicals in a shop window
Brodifacoum is a pest control chemical that kills by preventing clotting, causing massive internal bleeding. Mark Bolton / Getty Images

Brodifacoum is a potent anticoagulant that reduces the level of vitamin K in the blood, leading to internal bleeding and death. It's sold as a rodenticide under brand names including Talon, Jaguar, and Havoc. While it kills rats because they eat the tainted bait, it doesn't do people or pets any favors either, since even touching it can cause exposure. It permeates the skin and remains in the body for months. Animals that eat a poisoned rodent are also at risk.


A shelf of chemicals including Strychninum sulfuricum
Strychnine is a naturally-occurring poison that causes excruciating death as muscles contract and spasm. Ion-Bogdan DUMITRESCU / Getty Images

Strychnine is a naturally-occurring poison, mainly obtained from seeds of the Strychnos nux-vomica tree. It's a neurotoxin that acts on spinal nerves, causing victims to contort and convulse. It's commercially available as a pesticide for killing gophers and rats. Like Brodifacoum, it's dangerous to use because it presents a risk to children, pets, and other unintended victims.


A mural advertising the dangers of Polonium
Polonium is a radioactive element that was discovered by Marie and Pierre Curie. Hugh Rooney /Eye Ubiquitous / Getty Images

While there are many more compounds that could easily make this list, don't forget some chemical elements are deadly poisonous! Lead and mercury are horribly toxic. There's no "safe" exposure to lead, while mercury is much worse in its organic form than as a pure element.

Polonium and other heavy, radioactive elements pack a double-whammy. The element itself is toxic, plus the radioactivity breaks down the body's tissues. The lethal dose of this element is much smaller than that of any other poison on this list. Ingesting just 7 trillionths of a gram is enough to kill an adult.

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Your Citation
Helmenstine, Anne Marie, Ph.D. "10 Deadliest Poisons Known to Man." ThoughtCo, Aug. 28, 2020, thoughtco.com/deadliest-poisons-known-to-man-4058116. Helmenstine, Anne Marie, Ph.D. (2020, August 28). 10 Deadliest Poisons Known to Man. Retrieved from https://www.thoughtco.com/deadliest-poisons-known-to-man-4058116 Helmenstine, Anne Marie, Ph.D. "10 Deadliest Poisons Known to Man." ThoughtCo. https://www.thoughtco.com/deadliest-poisons-known-to-man-4058116 (accessed June 20, 2021).