Deadliest Poisons Used by Man

Since time began humans have looked for more and more effective ways of killing and maiming each other. For this end poison has always been a popular, if not a little sophisticated, choice. Even back in ancient times the rich, powerful and unpopular would employ a food taster to check whether their goat’s head soup had been dosed.

Poisoning has long been a popular way to murder those around you and the choice of assassins. It is subtle – hard to detect, effective and the culprit doesn’t even have to be on the scene of the crime. There is also the advantage that you don’t need strength or skill plus it’s great if you are a little squeamish about killing people. This may be why there have been so many documented women poisoners throughout history.

The list I have compiled here is not just a list of the top 10 most toxic substances known to man. That would be too easy and not really relevant to anyone. This list is all those deadly poisons that have, over the years, been used by humans to kill each other; either individually or en masse.

10. Arsenic


Arsenic is one of the classics. Hugely popular up to Victorian times, it was both easy to acquire and effective. It seems they couldn’t get enough of it, being a common ingredient in any number of household products from wallpaper to paints. Arsenic poisoning occurred accidentally from all these and natural sources with notable cases such as the loopy King George III of Britain.

The superficial effects of arsenic poisoning are jaundice and a skin rash, but this tends to be after a long build up. Acute poisoning from a high dose results in intense gastric distress – basically everything goes wrong with your gut causing vomiting, diarrhea and bleeding, along with pain.
Death follows convulsions and coma with circulatory failure being the ultimate cause. This may happen within a few hours of ingestion.

9. Mustard Gas

Mustard Gas in World War I

Mustard gas, or sulfur mustard, shot to popularity in World War I. It was obviously decided that being pounded by heavy artillery in the trenches wasn’t sufficiently unpleasant so German scientists invented the chemical weapon. The name comes from the yellow-brown colour of the gas and the garlic like smell. However, no cooking ingredients were used in its manufacture – the active ingredient is highly reactive chlorine.

Despite only being fatal in around 1% of cases I’m including mustard gas because of its horrific nature. Its mode of action is basically to burn any part of the body it comes into contact with, whether that be skin, eyes or lungs. It forms large blisters on the skin and lungs and can even damage DNA leading to cancer. The gas is also capable of penetrating clothes and remaining active in the soil for prolonged periods.

In fatal cases the cause of death is usually the result of burns or damage to the lungs causing suffocation. There is also a great risk of secondary infections from bacteria as with other serious burns.

8. Cyanide

Potassium cyanide

©Andy king50 / Wikimedia

Cyanide is one of the best known of all poisons. Perhaps best known as the suicide pills reputedly carried by secret agents it was also the active ingredient in the gas (Zyklon B) used by the Nazis in extermination camps such as Auschwitz. There is little doubt as to the effectiveness of this poison with death occurring almost immediately. Cyanide works by preventing cellular respiration; i.e. the body stops producing energy at the very lowest level causing what is termed “internal asphyxia”. This manifests itself in rapid breathing, dizziness, nausea, headache and ultimately convulsions.

Cyanide comes in two main forms hydrogen cyanide which is a gas and potassium cyanide which is a white powder. It occurs naturally in the stones of apricots, several plants and even apple pips. Whatever the source it is recognisable by a bitter-almond smell.

7. Strychnine

Another of the old favourites, Strychnine is infamous for its dramatic and painful effects. It works by attacking the central nervous system causing all the muscles in the body to violently contract at the same time. Such is the intensity of these convulsions that the victim will appear to “jackknife” back and forth in the latter stages of the poisoning.
Death occurs within 2 to 3 hours of ingestion and whilst usually the result of asphyxiation due to paralysis of the respiratory pathways it can also be caused by exhaustion from the convulsions.

Strychnine is derived from the seed of the dog button plant (Strychnos nux-vomica) which grows in tropical areas. In the past it was used to treat a wide range of medical conditions. These days though its primary use is as a pesticide and rat poison, however, some drug dealers apparently add it to heroine to smooth the effects!

6. Ricin

Ricin - Castor beans

©HediBougghanmi2014 / Wikimedia

Whilst castor oil may be touted for its health giving properties the other product of this plant (Ricinus communis) is the polar opposite. A dose of less than a sprinkling of salt will kill an adult. It is derived from the castor bean and it is the part that is left behind after the oil is extracted that is poisonous. Ingestion of ricin is actually not often fatal as it is difficult to digest; it is much more dangerous if inhaled or injected. That said the most common form of poisoning occurs from eating castor beans – why anyone would do this I have no idea but as few as 5 beans could prove fatal.

Ricin acts by preventing protein synthesis. This means cells slowly grind to a halt and essential operations cease as enzymes aren’t produced. It may take up to a day for symptoms to show and these will vary depending on the method of exposure.

Ricin is so good at killing people that both the USA and Russia stockpiled it as a chemical weapon. It is thought to have been used by Sadam Hussein on his own people and is linked to the KGB murder of  a Bulgarian writer in London.