Dry lips are mainly caused by environmental and physiological factors. Common causes include exposure to dry or cold air, wind, and sun damage, which strip moisture from the lips since they lack oil glands to retain hydration. Frequent licking of the lips can worsen dryness because saliva evaporates quickly, leaving lips drier. Dehydration, where the body lacks sufficient fluids, also contributes significantly to dry lips. Nutritional deficiencies, particularly a lack of vitamin B12 and iron, can result in persistent dryness. Other causes include the use of irritating lip care products, allergic reactions, certain medications, and underlying health issues like thyroid problems or autoimmune diseases. Lips are especially vulnerable because their keratin layer is thin, and they do not have sweat glands to maintain moisture, making them sensitive to external influences and easy to dry out.