There are long-standing rumors that some lip balms (Carmex in particular) are addictive or actually dry lips out. It turns out that these rumors are unfounded. The most commonly questioned ingredients found in some lip balms -- phenol, menthol and camphor -- don't actually dry lips out, in turn leading to repeated use and eventually addiction, as some suspect [source: Roach].
Really, just about any lip balm will keep your lips sufficiently moist. There are a few key ingredients you want to look for in a lip balm. Balms need a base, often petroleum, beeswax or other oil, which will provide a barrier to prevent moisture loss. Emollients like aloe or lanolin soften lips. Vitamins and nutrient-rich compounds are also often added to aid in tissue regeneration and protection.
You'll also want a balm that contains a level of sun protection -- at least SPF 15. Since your lips don't produce as much melanin as the rest of your skin, they need the extra protection from the sun's harmful ultraviolet (UV) rays. Most dermatologists also recommend applying petroleum jelly to your lips at night if you have severely dry lips.