DEAR DR. GOTT: Regarding SLS-free toothpaste, the Tom’s of Maine I recently bought does contain this substance. My chief complaint is dry lips. This means I’m constantly using lip gloss. Biotene toothpaste is the only one I have found to be SLS free that solves my dry lip problem.

DEAR READER: SLS (sodium lauryl sulfate) is a highly effective chemical found in industrial products used to remove oil stains and residue. In lower degrees of intensity, it is found in toothpaste, shampoos, conditioners and other products. The Biotene to which you refer, and Tom’s Spearmint Paste, are SLS free. Biotene contains aloe leaf juice, which might help your dry lips, but Tom’s contains glycerin as a moistener.

Because SLS can cause mouth irritation, some manufacturers offer alternatives, but it isn’t a necessary component.