Secret

What the ingredient list on a beauty product tells you, what the names mean, and what it leaves out, using FDA and EU labeling rules.

Ingredient lists run from most to least, but only down to 1%. Below that, any order is allowed. What the order shows and what it hides.

What the AAD, FDA and DermNet say about testing a small area, the FDA hair dye skin test, in-office patch tests, and contact allergy basics.