Eucalyptol

A spicy, oily extract of the eucalyptus tree, this is also a decongestant — it relaxes the mucus-producing cells called monocytes in your airways.

Menthol

The sensors in your body that detect cold are fooled as easily as a tourist in Times Square. When ingested or rubbed on the skin, menthol tricks them into telling the brain, "We're cool!" And psychologically, cool equals clean.

Methyl Salicylate

The chief constituent of wintergreen oil, this flavoring — a phenol — is found in root beer, Bengay, and cigarettes. It can also relieve mild aches and pains just like its salicylate cousin, aspirin.

Thymol

Phenolic compounds like this one disrupt the cell membranes of bacteria — including the ones living in your mouth. Thymol, obtained from thyme or oregano, was also used by ancient Egyptians (and Evita's embalmers) to preserve the dead.

Alcohol

FreshBurst Listerine is almost 44 proof. To keep it from being taxed as liquor, Johnson & Johnson denatures it — making it unpalatable. The company won't give its recipe, but perhaps coincidentally, denaturant formula 38-B contains eucalyptol, menthol, methyl salicylate, and thymol. The chemicals are coming from inside the house!

Sorbitol Solution

Original Listerine tasted awful; now there are yummier alternatives. Sugar promotes cavities, so J&J uses this sweetener and sodium saccharin, too.

Poloxamer 407

This petroleum-based detergent keeps oily ingredients in solution. Its secret talent is to remain liquid at room temperature but gel at body temp. That weird feeling on your tongue after you gargle could be P407.

Benzoic Acid

An aromatic carboxylic acid, this was discovered in 1556 by Nostradamus.1 He could never have predicted it would be used to keep bacteria and mold from growing in mouthwash.

FD&C Green #3

The color of a substance depends on the wavelengths of light it reflects and absorbs, and for an organic dye, that depends on the number and type of bonds between its atoms. This particular dye absorbs at 625 nanometers — perfect for displaying blue-green.

Note 1. Benzoic acid is an aromatic carboxylic acid, not a

phenol as previously reported.