Bitrex is...

Denatonium Benzoate – to give it its full, technical name. Ironically, that’s a bit of a mouthful. So we call it Bitrex®.
The bitterest substance known to man, woman or child. That’s according to The Guinness World Records.
A substance that’s put into household, garden and automotive products to ensure that if a child or animal ever tried to swallow it, they would spit it straight out before they could be poisoned.
Completely harmless if consumed. It just tastes really, really horrible.
A lifesaver. Literally.
The product of a happy accident. Bitrex was discovered in 1958 by a team of Macfarlan Smith scientists who were working on a new local anaesthetic. Our chemists realised immediately that they had found a remarkable substance – the world’s most bitter material – and quickly put it to good use...
Helping to make accidental poisoning a thing of the past.