Dry lips drinking water does not work may be the lack of vitamins, lipitis, personal habits and other factors caused by the following. 1. Lack of vitamins: like the lack of vitamin A, B₁₂, C, etc. can cause dry lips. (1) lack of vitamin A: will affect the synthesis of glycoprotein in the mucosal cells, affecting the formation of epithelial cells, dry lips and other symptoms. (2) lack of vitamin B₁₂: long-term lack of lip skin will lead to become sensitive, and then easy to cause dry lips, peeling, etc. (3) lack of vitamin C: affect the antioxidant response and collagen formation, causing dry lips, etc.. It is recommended to eat more fruits and vegetables, appropriate vitamin supplementation, such as vitamin C, vitamin B₁₂ and so on. 2. Lip inflammation: inflammation will stimulate the lip skin and mucous membrane, causing dry lips and other symptoms. It is recommended to use erythromycin ointment and other drugs, for local application, to keep the lips moist. 3. Personal habits: such as licking the lips with the tongue. When licking lips, look as if more moist, in fact, not, when the lips of saliva evaporation at the same time, will also take away the lips itself. Saliva in a variety of pro-digestive enzymes and bacteria, will stay on the surface of the lips, resulting in the destruction of the protective film of the lips, causing dryness, peeling, chapping and so on. It is recommended to change the bad habit of licking lips, and at the same time with the local application of petroleum jelly to keep lips moist. If the lips are dry and serious, it is recommended to consult a doctor in time to identify the cause of the disease, targeted treatment, drugs should be used in accordance with medical advice.