Sometimes cosmetics can cause lip chapping. Lipsticks contain a wide variety of chemicals, and those chemicals can damage lips oils. For example, the "propyl gallate" can easily cause a contact allergy.
Choosing proper lip care products can be difficult. The petroleum-based products are widely used, but sometimes they cause adverse reactions.
Flavoring agents are very popular. But many people are allergic. Artificial flavoring agents like red dye (candy, lozenges, gum, mouthwash) and cinnamon flavoring, can easily cause allergies.