These Are The 5 Deadliest Known Poisons In The World

By Jack Beresford

March 13, 2018

The mysterious poisoning of double agent Sergei Skripal via an unusual and unnamed nerve agent has put everyone across the UK on edge.

But how much do you really know about nerve agents and poisons in general? Here are the five deadliest known poisons in the world, how they work and their previous victims.



Just a couple of milligrams of this naturally occurring carbohydrate-binding protein are enough to kill someone. Ricin can be extracted from Ricinus communis seeds or Castor Beans and features prominently in the hit US TV series Breaking Bad.

It works by preventing the production of essential proteins. Soon enough the central nervous system, kidneys, liver and other organs fail. Death by multiple organ failure or cardiovascular shock follows soon after.

The most famous case of death by Ricin poisoning came back in 1978 when a Bulgarian communist agent fired a tiny bullet containing the substance into the leg of defector Georgi Markov. He died three days later with speculation suggesting the KGB may have provided the poison.



Though more commonly associated with cosmetic surgery Clostridium Botulinum or Botox is a ubiquitous bacterium that can only develop and multiply in oxygen-less environments. Botox works much like a tetanus infection., with the neurotoxic protein blocking nerve cell signal transmissions.

The result is paralysis of the vegetative nerve system and muscle weakness. Any paralysis of lung function can be fatal while just 0.3 micrograms of Botox is enough to kill someone. The story goes that the CIA once had a plot in place to kill Fidel Castro using a Botox contaminated cigar, those the claims have never been fully substantiated.



Batrachotixin is a powerful neurotoxine created using the steroidal alkaloid produced by poison dart frogs. As little as 0.2 grams is enough to kill someone with the toxin causing arrhythmias and ventricular fibrillation in heart muscles, wich results in a cardiovascular arrest.

BTX is famously tricky to produce on a mass scale though – dart frogs only produce the necessary toxin in Central and South American rainforest conditions, due to the type of beetles and insects they ingest. They are also an endangered species and with thousands of frogs required to create enough BTX to kill a human, it’s unlikely many people will suffer this kind of fate.


Polonium 210

With a half-life of just 138, it’s near impossible to detect the use of Polonium 210 unless investigation begins almost immediately. Only nuclear powers are able to produce the amount of Polonium needed to cause death and it cannot be bought on the open market.

Several hundred kilograms of raw uranium ore, housed in nuclear reactor, are required to make the lethal 100 nanogram dose needed. Polonium is generated by bombarding bismuth with neutrons. It’s not particular dangerous to handle – the radioactivity would not even penetrate paper. But inhale of ingest polonium and the poision works by damaging the stomach lining, destroying leukocytes in the blood and resulting in anemia. It also destroys stem cells and prevents them from multiplying. The victim dies in a matter of days or weeks.

The most famous acknowledged case involved former FSB agent Alexander Litvinenko who died in London in 2006, after an unknown assassin poured the substance into his tea. It took 23 days before Litvinenko died.



First discovered by chemist Ranajit Gosh during research on pesticides in the 1950s at the labs of the British Imperial Chemical Industries, VX ranks as the most dangerous known chemical nerve agent in the world.

Just 0.4 miligram is enough to kill a grown man, while the poison can permeate the skin leading to a painful death. Banned under the 1997 Chemic Weapons Convention, VX was used in the 1988 mass killing of 5,000 Kurdish civilians by Saddam Hussein in Halabja and, more recently two women sprayed the substance into the face of Kim Jong Nam the half-brother of Kim Jong Un in Kuala Lumpur. He died shortly after.