I've heard that nicotine (contained in tobacco) is even more toxic than potassium cyanide (KCN, often used for suicide, at least in movies...).

I tried to research a bit, but could not find any directly comparable values and I'm not educated enough in toxicology to understand their meaning.

For nicotine, if taken in orally, I found values about 50-60mg/kg to be the lethal dose for adult humans. There were also sources mentioning far higher doses like 300mg/kg.

Finding lethal dose values for potassium cyanide was much harder, I found one source speaking of 200mg/kg orally for adults, but I'm not sure if that's true.

Can you please help me to compare the toxicity of those two substances and interpret them?

1 Answer 1


Most medical literature reports a similar level of toxicity between nicotine and cyanide - 50 mg for cyanide and 60 mg for nicotine as lethal doses. However, there is controversy over the true lethal dose for nicotine (but not for cyanide). An article by Dr. Mayer in Archives of Toxicology postulates that the true lethal dose for nicotine is 10 times higher than 60mg or 600mg. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3880486/

  • 1
    Welcome to health SE :-). A great answer. If you have the time I think it would be even more helpful for the OP and the other users if you edit it to add a reference for the cyanide lethal dose (it is implicitly shown in the reference you provided, by stating it is similar to that of nicotine, but I haven't found the exact number for cyanide there) and if you specified whether it is 50/60 mg/kg or 50/60 mg for an average adult human. Thanks!
    – Lucky
    Jul 15, 2016 at 19:55

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