An arid environment, temperature extremes or overexposure to the sun can cause dry, chapped lips. While lip balms and oils provide a protective barrier to keep moisture from evaporating and leaving your lips dry, these products work best when the outermost layer of dry skin sloughs away to reveal new skin. Baking soda is a natural exfoliant that removes old skin from chapped lips and leaves them smooth.Causes of chapped lipsWithout a protective barrier, all skin loses its moisture to evaporation. Elsewhere on your body, sebaceous glands produce an oily, waxy substance called sebum that protects your skin. Lips have no such protection, leaving them vulnerable to drying and chapping. Cold air, wind and sun exacerbate chapping.Licking chapped lips may feel refreshing temporarily, but as saliva evaporates, it carries with it residual moisture in your lips so they feel even drier. A stuffy nose often precedes a case of chapped lips; breathing through your mouth dries lips.ExfoliationDermatologists refer to removal of the outermost layers of the epidermis as exfoliation. Chemical exfoliation includes acidic peels and enzymes, while mechanical exfoliation refers to gentle abrasion.Gritty products exfoliate your skin mechanically, rubbing away shed skin cells that remain on the surface of your skin to uncover newer layers of skin beneath them. Baking soda's fine grains act as a mechanical exfoliant on skin and lips.Mix just enough water and vegetable oil with baking soda to form a paste and rub the mixture on your lips with your finger or a dampened washcloth. Press as lightly as if you were applying lip gloss with your finger; rubbing too hard could injure delicate skin.ProtectionBaking soda is highly alkaline. While this characteristic won't harm your lips in the short term, you must rinse your skin thoroughly after exfoliation with baking soda to avoid possible irritation. Alkaline substances feel slightly slippery in water, so rinse for 15 to 20 seconds or until your lips no longer feel slippery.After rinsing thoroughly, preserve the moisture in your newly smooth lips with a lip balm, oil or petroleum jelly to form an occlusive layer between your lips and the surrounding environment.CautionsExfoliating chapped lips with baking soda works well for mildly to moderately chapped lips, but not for cracked or bleeding lips. Ask your doctor or pharmacist about a medicated balm to help your lips heal before attempting to smooth them through exfoliation.Cheilitis, a more serious lip condition that may involve infection or inflammation of deeper tissues, necessitates a visit to a doctor for treatment. Because severe chapping and cracking can indicate other illnesses, your doctor may want to rule out other potential causes.