• Question: why do onions make you cry?

    Asked by bryn_ie to William, Thibaut "Tibo", Harry, Georgia, Emily, Aimee on 9 Nov 2019.
    • Photo: Harry Wilkinson

      Harry Wilkinson answered on 9 Nov 2019:


      When you cut an onion some chemicals get released which are ‘lachrymators’. This just means a chemical which reacts with the glands in your eyes that produce tears and makes you cry!

      There’s a chemical that I use in my work called ‘benzyl bromide’ which does the same thing but a lot worse! Once someone throw some of it in the bin in the lab and we all had to leave because we were all crying so much!

    • Photo: Thibaut Deviese

      Thibaut Deviese answered on 11 Nov 2019:


      Harry already gave a very good answer to this question! My solution to this problem is to not cook with onions 😉

    • Photo: Aimee Egglestone

      Aimee Egglestone answered on 12 Nov 2019:


      My gut response was to say “Because they’re really mean” but Harry’s answer is better!

    • Photo: Emily Sparkes

      Emily Sparkes answered on 18 Nov 2019:


      What Harry said! It’s interesting how some onions make you cry more than others though. I once accidentally gassed my lab with benzyl bromide because my fume hood stopped working, but I was the only one it didn’t affect, weirdly! Onions make me cry loads though. I find putting a spoon in my mouth helps. Some people think this is because the lachrymators bind to the metal of the spoon, others think it’s a placebo that just distracts you, but there doesn’t seem to be any conclusive evidence

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