My 4 yrs old son's dry lips condition keeps coming back for about two months now after few days. we keep him hydrated and use chap stick + oliv oil?

Hydrate inside: If your son licks his lips frequently due to the dryness then it will be hard to keep his lips hydrated. The constant licking maintains the dry skin that becomes hard to maintain with only topical moisturizers. Try maintaining appropriate hydration from within, plenty of water. Most of us do not take in enough water and this keeps the skin dry. Also change from chap stick to vaseline