Dry lips, or chapping of the lips, is usually causes by mechanical factors which remove the moisture from the surface of the lips. For example, chronic chapped lips are most common in those who have a habit of constantly picking at or licking the lips. If you have this habit, and you can learn to control it, things should get a lot better.
It is also possible to get eczema
, which is a dry, inflammatory condition of the skin, that also affects the lips. It is unusual to have eczema just on the lips, but if you have it on other parts of the body, then it is also possible that the dryness of your lips is from this. Eczema is usually treated but keeping the affected areas well moisturized. It may also be necessary to use a steroid cream to get the itching and redness down, and your primary care doctor
can advice you on this as you should not use steroid creams on the face except under medical supervision.
Finally, if the dryness of your lips is just at the corners of the mouth, this may be a different condition called angular cheilitis, which is sometimes do to a fungal infection and other times due to a nutritional deficiency.
Start by talking to your primary care doctor, who will be able to help.