Get slick. It's a myth that some moisturizers leave your lips needing more balm, but there are some formulas that are better than others. Ingredients such as petrolatum, shea butter, hyaluronic acid, and dimethicone are all good at restoring moisture. The most important thing is to use a balm that's viscous, not waxy, so ingredients penetrate fissures. If you have chronic chapping, look for a lip treatment that contains ceramides, which help restore the skin barrier.
• Stay pure. There are some ingredients that can make chapping worse. Anyone with eczema should make sure her balm doesn't contain lanolin. Since fragrance is the number one skin allergen, stay away from heavily scented or flavored balms; cinnamon can be particularly irritating. (Menthol actually soothes itching, though.) If you want to exfoliate your lips, use lip balm with a touch of alpha hydroxy acid, such as EI Solutions Lip Refine, rather than a grainy scrub or a washcloth.
• Watch your mouth. Besides dehydration, the other main cause of chapped lips is a disruption in the pH balance of skin, which needs to be slightly acidic in moist areas like the mouth. Toothpastes, mouthwashes, and skin cleansers can alter this balance, so apply balm after you brush your teeth or wash your face. If you suspect your toothpaste may be part of the problem, consider one called Squiggle—it doesn't contain sodium laurel sulfate, and it makes a big difference with persistent chapping.
• Go with a pro. If you find your lips won't stay smooth and healthy, visit your dermatologist. You could be having an allergic reaction to something. And painful cracks at the corners of the mouth also necessitate a call to the doctor; they're almost always caused by perleche, an inflammation that requires a prescription antifungal.