What is Bitrex?
Bitrex (denatonium benzoate) is the world's most bitter substance. It is a safety additive in household automotive and garden products. It is also an animal repellent.

Who makes Bitrex?
Macfarlan Smith discovered Bitrex and manufactures it in Edinburgh, Scotland. Bitrex is distributed in the USA by Market Actives, LLC of Portland, Oregon.

How bitter is Bitrex?
Humans are very sensitive to Bitrex. Taste testing has determined that people can detect Bitrex in water at 50 parts per billion. Bitrex is aversively bitter at 1 to 10 parts per million (ppm) in water. Most consumer products become bitter at 30 to 100 ppm.

Do babies and children respond to bitter taste?
Yes. Bitter taste response has been shown in infants at birth. Testing with Bitrex in 18-48 month-olds shows an 85% volume reduction in liquids swallowed. As many poisonous plants contain bitter alkaloids, it is thought that bitter taste is a natural warning to discourage swallowing.

What is Bitrex made of?
Bitrex was discovered by Macfarlan Smith during research on derivatives of the anesthetic lidocaine.

How is Bitrex tested?
The only way to test Bitrex is human taste testing. Volunteers are paid to taste products with and without Bitrex. 

Why taste test all products?
Bitter taste perception can be affected by many factors such as viscosity, solids content, inherent taste and even fragrance. Each formulation can be very different with only minor ingredient changes.

Don't most products already taste bad?
Surprisingly, many products do not taste bad and some are even sweet, like antifreeze, rat bait or lead paint. Bitrex ensures they taste awful.

Does Bitrex affect product performance?
No. Bitrex does not affect product performance, appearance or fragrance at the low concentrations used to be effective.

Can Bitrex be added to all products?
The National Safety Council and American Medical Association recommend bitter agent use, along with other safety measures, in products defined as mild to moderately toxic. Some products are not appropriate for Bitrex, such as corrosive or highly toxic products.