Lip allergy & eczema. Persistent chapped lips is lip eczema, which can be treated like skin eczema, using Hydrocortisone cream plus vaseline or aquaphor to retain moisture. Sometimes, lipsticks or lip sunscreen chemicals are causing an allergic reaction on the lips. Other times, a person is a primary lip-licker (it's his habit). Once cracked, lips get irritated by routine foods and juices. A doctor can sort things out.
Need more info. Are you talking about lip products? (lipstick, etc) or lip swelling, peeling, etc?