The two most dangerous and fast-acting poisons are hydrogen cyanide and botulinum toxin, which can kill within very quickly, according to Planet Deadly and the Organisation for the Prohibition of Chemical Weapons. The speed with which poisons kill depends on the dosage and route of entry.
Hydrogen cyanide is a simple compound, explains the Organisation for the Prohibition of Chemical Weapons. This deadly chemical is liquid at room temperature and can be easily aerosolized, or broken up into little droplets in the air. The most deadly route of entry is inhalation. Inhalation of more than 3 grams of this substance is considered to be fatal to a human in less than one minute.
Botulinum toxin is produced by the bacterium Clostridium botulinum. It is estimated that less than 1 nanogram per kilogram injected directly into the bloodstream is enough to kill a person in several days, states Planet Deadly. This drug induces paralysis of every muscle in the body, causing the individual’s heart and respiratory system to stop working. This deadly toxin is the main ingredient in Botox, which is as an anti-aging treatment. Botulinum toxin is also used to improve the quality of life of individuals who suffer from a variety of illnesses, such as urinary incontinence and chronic migraines.