Q: I recently used a hypoallergenic serum that left my complexion irritated. Aren't these products supposed to be good for sensitive skin?

A: If a new product irritates your skin (stinging and redness are usually the first signs), stop using it immediately. If you suffer from these symptoms and swelling develops 24-36 hours later, you could be allergic to ingredients in that product, explains Karyn Grossman, M.D., a dermatologist with offices in New York City and Los Angeles.

First, though, you should know that hypo is a Latin prefix meaning "less than normal," so hypoallergenic means there are fewer -- not no -- ingredients in a product that might irritate your skin. The top allergens in beauty products are fragrances, botanicals, dyes and (in cleansers) detergents, so these are often excluded from products labeled "hypoallergenic." But if your skin is unusually sensitive, you may react even to products labeled as hypoallergenic.

Look for dermatologist-recommended products that are dye- and fragrance-free, and ones labeled for sensitive skin. Try Dove's new Sensitive Essentials, a line of cleansers ($7) and moisturizers ($7.49; all at drugstores) formulated with fatty acids to form a protective barrier on skin, making it less prone to irritation. Neutrogena and Purpose (both at drugstores) also offer several choices, from cleansers and moisturizers to masks and exfoliants, for sensitive or easily irritated skin, and Almay's hypoallergenic cosmetics (also at drugstores) are specifically formulated for sensitive skin and are allergy-tested. If you still have problems, though, consult your dermatologist or an allergist; he or she may be able to pinpoint the specific ingredients that are causing your skin to react.