5 Deadliest Poisons Known to Man and Their Effects

Updated on September 17, 2019

Whether you plan to use the following information to murder your ex-wife or to make the dog next door shut up once and for all, use it wisely. The following article contains information about the deadliest substances known to man, either inhaled or ingested.

A poison is described by the ever-faithful Google as "a substance that, when introduced into or absorbed by a living organism, causes death or injury"—and the following five are the most dangerous found on earth.

A poison is only defined by the dosage. For example, even drinking too much water could kill a human (although it would have to be about two swimming pools worth). So, something is only officially defined as a poison when administered in a dose that causes harm or death.

5 of the Most Dangerous Poisons and Their Effects

  1. Botulinum Toxin or Botox
  2. Ricin
  3. Anthrax
  4. Sarin
  5. Tetrodotoxin


1. Botulinum Toxin or Botox

Botulinum toxin is a protein produced by a bacterium called Clostridium botulinum and other related species. Where do they come up with these names? Anyway, this bacterium produces the botulinum toxin, which is a neurotoxin, meaning the toxin inhibits neuron control in the body.

The toxins produced by the bacteria are some of the most powerful neurotoxins known to man; however, you may have heard of them as "botox." But now you're wondering, "why didn't those injections my mother-in-law had a few months ago kill her, then?" Well, the doctors that perform botox surgery are highly skilled (granted you pick a proper one) who know just the right amount of Botulinum toxin to inject into the patient.

What the toxins do is attack the neurotransmitters responsible for triggering muscle contractions so the muscles cannot be released. This gets rid of the wrinkles in people's faces to some degree; however, it's not permanent and needs topping up every few months.

What Causes Botulism?

There are several causes of botulism⁠—foodborne botulism, wound botulism and infant botulism. Foodborne botulism is most commonly caused by eating from improperly canned foods that contain the toxin. In wound botulism, the toxin enters the body through an open wound. In infant botulism, bacteria is usually consumed by the infant, which then produces the toxin.

The bacterium usually grows on improperly handled or prepared meat products, and consumption can lead to paralysis, which in the worst cases can lead to death. In less severe cases, the ingestion of the toxins causes minor and temporary muscle paralysis.


  • Paralysis
  • Difficulty swallowing and dry mouth
  • Nausea and vomiting
  • Trouble breathing
  • Facial weakening
  • Blurred vision

The Caster Oil Plant
The Caster Oil Plant | Source

2. Ricin

Ricin is a highly toxic protein that occurs naturally in the castor oil plant, Ricinus communis. Ricin is poisonous to humans if inhaled, injected or ingested, and a dose the size of a few grains of table salt can kill an adult human. Yikes! It's undoubtedly very dangerous, yet it is grown somewhat commonly in gardens in Britain.

Ricin prevents cells from combining amino acids it receives from the ribosomes of the cell, to create proteins. This is essential to all living cells, so without it, the consequences aren't too fabulous. The symptoms caused by lack of protein after receiving a dose of ricin can be severe diarrhea, and some victims can die of shock. However, death usually occurs after about 3–5 days of exposure. Other effects range from seizures to hypotension (abnormally low blood pressure). Lovely.

The ricin itself comes from the inside of Castor beans, produced by the plant. Ingestion of 5–20 of these can prove fatal for an adult.

3. Anthrax

Not to be confused with the thrash metal band from New York, Anthrax is an infectious disease caused by a bacterium called Bacillus anthracis. The bacterium can produce spores that are able to survive in extreme conditions, even in places such as Antarctica. (There was even a case where disturbed graves of animals caused reinfection after 70 years of the animal being dead.)

When these spores are inhaled, ingested or touched by a cut in the skin, they reactivate and multiply rapidly within the host. Anthrax poisoning symptoms start with a painless ulcer on the area of entry; however, that starts to get much worse. The lymph glands around the ulcer start to swell up, and the ulcer grows with a characteristic black dying area in the centre. Sufferers may also experience vomiting of blood, loss of appetite and inflammation of the intestinal tract. The throat and mouth can also develop lesions causing large amounts of pain.

If left untreated, anthrax leads to death. However, luckily there is a vaccine, created in 1881 by Louis Pasteur, a French scientist, and this has been further improved by scientists today.

A Sarin chemical weapon
A Sarin chemical weapon | Source

4. Sarin

Sarin is an organic compound that is found as a clear, odourless liquid. It is an extremely powerful nerve agent, estimated at 500 times more toxic than cyanide, and has been used in chemical warfare, a famous example being the sarin gas attack on the Tokyo subway.

The two main ways to be affected by sarin are via inhalation and absorption through the skin. Even at very low concentrations, sarin can be fatal, and even people who receive a nonlethal dose who are left untreated can suffer permanent neurological damage. Those who suffer a lethal dose are sadly left to the following death:

"Initial symptoms following exposure to sarin are a runny nose, tightness in the chest and constriction of the pupils. Soon after, the victim has difficulty breathing and experiences nausea and drooling. As the victim continues to lose control of bodily functions, the victim vomits, defecates and urinates. This phase is followed by twitching and jerking. Ultimately, the victim becomes comatose and suffocates in a series of convulsive spasms." -Wikipedia

Needless to say, sarin does not sound particularly pleasant, and what's worse is that any clothing that comes into contact with sarin vapour can still maintain that vapour for up to 30 minutes, meaning lots more people can inhale it.

Fugu Puffer Fish containing Tetrodotoxin
Fugu Puffer Fish containing Tetrodotoxin | Source

5. Tetrodotoxin

The things we put ourselves through for good food—well, that's if you consider the organs of a pufferfish to be good food. The tetrodotoxin or TTX is a potent neurotoxin to which there is no known antidote. It is commonly found in pufferfish but can also be found in some types of newt, toad, octopus, sea stars, angelfish and flatworm. It is used in the animals as a biotoxin to warn predators and keep them away, or as a venom in some octopi.

It is extremely toxic and can get into the human body by almost any means—ingestion, inhalation or through cuts in the skin. What the toxin does is block sodium channels in the body that are required for transmission of signals between the body and brain. Therefore, the symptoms of Tetrodotoxin poison are paralysis of muscles, loss of sensation and loss of regular heart rate—meaning that around six hours after consumption, death will occur.

The pufferfish containing the nasty toxin are a delicacy in Japan, and the toxin is not removed from the organs after cooking. Amazingly, people still put their neck on the line to try the fish. Up to five Japanese people die on average every year from eating poorly prepared pufferfish organs.

Well, there you have it! The top five deadliest poisons known to man. I hope this hasn't worried you too much; there are antidotes for many of them, and some in development for the ones that don't have one yet. It's amazing to think that things as simple as plants can produce such powerful poisons that they could easily kill us. It just goes to show that man is not invincible.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

Questions & Answers


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        Kevin Onyango 

        6 months ago


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        7 months ago

        Wow. Very fun and cool

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        Abdi hashi 

        8 months ago

        yeah I love it too

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        sadab saman 

        2 years ago

        that is so cool


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