Why do lips seem to peel often even though they are not chapped?

Winter weather/sun: The skin on the lips are sensitive to weather changes. So if it's extremely dry, cold, hot, and dehydrated, you could possibly have dry lips that are flaking. Also sunburned lips flake as well. So make sure that well hydrated, and/or using a lip balm to seal in the moisture. Your using claritin, (loratadine) and history of eczema indicates you take antihistamines that dry mucous membranes, and you have sensitive skin.

Might be toothpaste: Closys toothpaste has fewer chemicals to address this problem. You could try brushing with baking soda to see if the peeling stops. You can also lubricate lips with vaseline or aquaphor or chapstick.

Wind and Sun: I find that lips peel and exfoliate with exposure to wind or sun. Dehydration is also a common culprit to allow lips to peel. Keep up the water intake, put on the lip balm and monitor your allergies. You mentioned a skin issue, is it near your lips? What creams do you use on it? Perhaps they are related.