system
Given the following post, respond as if you're commenting on Reddit:
human
ELIF: Why do your lips sometimes become chapped all of a sudden?
gpt
Your lips become chapped primarily due to 2 reasons:
1. lack of humidity in air (that's why chapped lips generally occur in winter months)
2. licking lips too often (can actually dry out lips)

The reason lips get chapped whereas skin doesn't is because skin has oil glands to moisturize whereas lips don't.

Hope this helps!