The Most Bitter Substance

Denatonium benzoate (C₂₈H₃₄N₂O₃) is recognized as the bitterest substance known. When it is added in only minute quantities to potentially harmful household, garden or automotive products, this harmless additive renders these products unpalatable and becomes a powerful deterrent against poisoning especially in young children.

Denatonium benzoate is a close relative of the local anesthetic lidocaine that has been used in dental surgery. During laboratory studies on this compound, it was noted that at a certain stage of the reaction, a very bitter tasting substance was created.

In 1995, Oregon's legislature required antifreeze and windshield washer fluid to contain denatonium benzoate, and the adoption of this policy by other states should reduce the number of cases of ethylene glycol (a common component in antifreeze) and methanol (often found in windshield wiper fluid) poisonings.

Macfarlan Smith Ltd, a company in Edinburgh, Scotland manufactures and sells denatonium benzoate under the brand name, Bitrex™. Products containing and carrying the "Contains Bitrex™" logo have been carefully evaluated to ensure that Bitrex™ remains stable in the product and that it is extremely bitter.

Bitrex™ provides protection against everyday menaces around the home. The sad fact is that, all over the world, thousands of young children require hospital care as a result of swallowing ordinary, every-day household chemicals. These might be commonplace detergents and cleaners or other products such as antifreeze, slug pellets or pesticides, but they all cause untold anguish for children and their parents.

Macfarlan Smith Ltd discovered denatonium benzoate in 1958 and it has manufactured and sold this product under the Bitrex trademark in the United Kingdom, the USA, Canada and elsewhere for over 40 years.