What is the cause of chapped lips?

Having chapped lips is a problem typically associated with winter, although some people may experience it at other times of the year. This can be quite simply explained by the drop in temperatures during winter, which puts this delicate area to the test. Indeed, when it's cold, the microcirculation in the lips slows down, leading to a reduction in the supply of nutrients and oxygen necessary for their regeneration. This phenomenon weakens the skin tissues, which are already naturally sensitive, and makes them more prone to cracks and flaking.

In parallel, the wind, typically blowing stronger in winter, exacerbates the impact of low temperatures on the lips. It consequently weakens the hydrolipidic film, which is already virtually absent on the lips, making them highly susceptible to various environmental assaults. The wind also tends to have an irritating effect on the horny layer and promotes the formation of small cracks. These cracks serve as prime entry points for bacteria and external irritants, potentially leading to local inflammation and increasing sensations of tightness and discomfort.

Dry air, whether it's due to the climate or domestic heating, is a major cause of chapped lips. Indeed, when the humidity in the air is low, the skin of the lips, which is already almost devoid of sebaceous glands and hydrolipidic film, rapidly loses its water content through a phenomenon known as insensible water loss. This natural evaporation is exacerbated by dry air, which draws moisture from the superficial layers of the epidermis. The result: lips become dry, rough and more susceptible to cracking.

Furthermore, in winter, the lack of humidity in the outdoor air often combines with the warm, dry air of heated interiors, thereby exacerbating the dehydration of the lips. This issue, which also affects the skin of the face and hands, particularly impacts the lips, whose horny layer is thinner than on the rest of the body. A similar phenomenon is observed in hot and dry climates, where prolonged exposure to arid winds or air conditioning in enclosed spaces amplifies the water loss from the lips and can lead to chapping.

Even though it may seem to alleviate lip dryness, the habit of licking one's lips can, in fact, exacerbate chapping. Indeed, when we lick our lips, saliva, although moist at the point of application, causes a rapid dehydration of the skin when it evaporates. A vicious cycle then sets in: saliva temporarily moistens the skin, but its evaporation accelerates moisture loss, which intensifies the sensation of dryness. As a result, we lick our lips again to relieve the discomfort, thereby worsening the chapping and perpetuating the cycle of dehydration.

Furthermore, saliva, primarily composed of water, also contains enzymes, such as amylase, which can alter the structure of the skin on the lips. These enzymes, designed to break down food in the mouth, can destabilise the skin barrier when frequently applied to the lips. Thus, saliva does more than just dehydrate the lip skin: it alters its lipid composition, weakening its barrier function and increasing its vulnerability to external aggressions.

If you experience a feeling of dryness on your lips, it is better to apply a emollient lip balm.

Chapped lChapped lips can sometimes be a sign of a nutritional deficiency. Indeed, certain nutrients are closely involved in maintaining skin hydration and in cellular regeneration, and their absence can disrupt these processes and increase lip sensitivity. Among the nutrients associated with chapped lips, we notably find vitamins A, B2, B6, C and E, and zinc. Each has a different mode of action.

For instance, Vitamin A plays a role in the renewal of cells and in the repair of skin tissues. A deficiency in this vitamin can weaken the skin and promote chapping of the lips. As for Vitamin B2, it aids in combating dehydration. Vitamin B6, on the other hand, is involved in the synthesis of collagen and a deficiency in this vitamin can weaken the skin's ability to maintain its elasticity. Lastly, the Vitamin C, well-known for its antioxidant properties, is also essential for the production of collagen and the repair of skin tissues.

Adopting a balanced diet, essential for maintaining health, is also important for preventing chapped lips.

Often underestimated, stress can also impact the health of the lips and play a role in their chapping. One of its main effects on the skin is the increased production of cortisol. When this hormone is synthesised in excess, it can weaken the skin barrier by reducing the skin's ability to retain water. As a result, the skin of the lips becomes drier and is indeed more likely to crack. Furthermore, stress can alter behaviours and increase the tendency to frequently lick the lips, which, as previously explained, dries out the skin in this area and promotes chapped lips.

Finally, stress impacts the immune system and weakens it, which can make the skin more susceptible to infections and inflammations. Therefore, when the lips are already damaged by the cold or dehydration, stress can exacerbate this situation by slowing down the healing process and making the chapping persistent.

Allergies can also play a role in the occurrence of chapped lips. One of the common forms of allergy is contact eczema. This reaction is triggered following contact between the skin and a substance it cannot tolerate. For example, it could be an allergen contained in a cosmetic product, such as a lip balm or toothpaste. Among the most common allergens, we find perfumes, certain preservatives or even essential oils. It should be noted that allergic reactions are not always immediate and can appear several hours, or even a few days after exposure to the allergen.

Irritants, which are distinct from allergens, can also be contributing factors to chapped lips. For instance, certain foods, such as citrus fruits, are known to irritate the skin and cause tingling sensations. The acids present in these fruits can damage the skin barrier and cause micro-traumas, thereby increasing the vulnerability of the lips and their risk of becoming chapped. Certain cosmetics, containing drying ingredients, such as alcohols, can also be the source of irritation.

Another potential cause of chapped lips: infections. One of the most common is oral herpes, caused by the herpes simplex virus. This viral infection frequently affects the lips and causes the appearance of small, painful, fluid-filled blisters. Oral herpes can also weaken the structure of the lips and cause cracks, making the skin even more vulnerable to dehydration and secondary infections. This infection is often triggered by cold, stress, prolonged exposure to the sun, or even lip dehydration.

Less common than viral or bacterial infections, fungal infections can also be responsible for chapped lips. Notably, this includes candidiasis, caused by the fungus Candida albicans, which presents as redness and irritation, sometimes accompanied by cracks. Candidiasis can be the cause of a perlèche, a painful inflammation located at the fold of the lip corner. An antifungal treatment is then necessary to curb the infection.

Finally, lips can become chapped as a result of taking certain medications. One of the most common groups responsible for chapped lips are retinoids, specifically isotretinoin, an oral medication. Used to treat acne, this derivative of vitamin A accelerates cell renewal and drastically reduces sebum production by the sebaceous glands, thereby eliminating part of the hydrolipidic film that protects the skin. Patients undergoing this treatment often observe a drying of their skin, particularly on the lips, which can lead to chapped lips. To counterbalance this side effect, it is recommended to regularly apply a rich lip balm.

Note : Certain diuretics, antibiotics, antidepressants, and antihistamines are also likely to cause lip dehydration, which can lead to chapped lips.

• FISTAROL S. & al. Dermatology of the lips: Inflammatory diseases. Quintessence International (2014).

• LUGOVIC-MIHIC L. & al. Differential Diagnosis of Cheilitis - How to Classify Cheilitis? Acta clinical Croatica (2018).

• BIANCONI F. & al. In Vivo Assessment of Water Content, Trans-Epidermial Water Loss and Thickness in Human Facial Skin. Applied Sciences (2020).

• PARK S. G. & al. Relationship between lip skin biophysical and biochemical characteristics with corneocyte unevenness ratio as a new parameter to assess the severity of lip scaling. International Journal of Cosmetic Science (2021).