I have really dry lips?

Im always using lip balm or vaseline, at least once an hour and it does my head in, I have to keep at least 3 in my bag, one in my pocket, one at work and then at home. Its really annoying always having to use stuff on my lips and I dont understand why my lips are always so dry. I dont use lipstick or gloss or... show more Im always using lip balm or vaseline, at least once an hour and it does my head in, I have to keep at least 3 in my bag, one in my pocket, one at work and then at home. Its really annoying always having to use stuff on my lips and I dont understand why my lips are always so dry. I dont use lipstick or gloss or anything like that.

Any help?
Update: Thanks guys - I drink an awful lot of water, barely drink anything else except a coffee most mornings.
=(
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