The various types of chapping and their causes.

Some instances of chapped lips do not arise from environmental causes but from mechanical factors. These mechanical cheilitis often result from chronic irritations caused by habits, anatomical abnormalities, or objects in contact with the mouth. For instance, friction from a poorly fitted dental prosthesis, constant contact between teeth and lips due to dental deformity, or frequent use of musical instruments or pacifiers. Mechanical lesions often appear on the lower lip in the form of scales.

Some nervous habits also play a role in the onset of mechanical cheilitis. Besides frequently running the tongue over the lips, biting one's lips, a behaviour particularly observed during periods of stress or anxiety, can lead to chapping. This is often accompanied by peeling on the inner surface of the cheeks.

Lacking melanin, lips are highly sensitive to the sun and can be prone to a specific form of chapping: actinic cheilitis. This condition occurs when the lips are intensely and/or repeatedly exposed to UV rays and is characterised by red, swollen, and painful lips. In some cases, blisters and crusts can form, and the lips can crack.

Individuals with a light phototype or those who have worked outdoors for many years are most at risk of suffering from actinic cheilitis. It's worth noting that this type of lesion, classified as potentially malignant by the World Health Organisation (WHO), can progress into a squamous cell carcinoma. In cases where such progression is suspected, a biopsy is generally performed.

The risk of actinic cheilitis underscores the importance of not neglecting sun protection for the lips.

Smoker's leukokeratotic cheilitis typically manifests on the lower lip, at the usual point of contact with the cigarette. It is characterised by a white patch, known as leukokeratosis, which gives the condition its name. This can be thin and uniform or thicker and irregular. It results from chronic irritation caused by the heat and toxic substances contained in tobacco smoke, such as nicotine and carbon monoxide. Indeed, it is worth remembering that smoking, in addition to affecting overall health, has harmful effects on the skin, including the lips.

Smoker's leukokeratotic cheilitis often requires careful management as it can conceal dysplasia or carcinoma. When detected, a biopsy is often performed to assess the severity of the lesion. In some cases, quitting smoking may be enough to achieve a complete regression of smoker's leukokeratotic cheilitis.

Cheilitis related to a contact eczema results from a delayed hypersensitivity that appears several days after exposure to an allergen that the body cannot tolerate. Depending on the reaction phase, the symptoms can vary slightly and can range from a subtle lip swelling to cracks, including lip peeling. In some cases, blisters may form and be accompanied by more or less intense itching.

Many substances can cause contact eczema on the lips. Most often, this follows the application of a lipstick or lip balm containing an allergen, such as limonene or linalool. The agent responsible for cheilitis can also be found in toothpaste, mouthwash, or in flavoured chewing gum or sweets. Finally, some nickel-based dental prostheses can cause oral allergy.

Only the identification, often carried out using patch tests, and the avoidance of the allergen responsible for cheilitis can halt the progression of lesions and their recurrence.

Infectious cheilitis, often classified as angular cheilitis, is caused by the proliferation of a microorganism on the lips, whether or not it belongs to their natural flora. There are three types of infectious cheilitis, depending on the nature of the pathogen:

• Bacterial Cheilitis.

  Often observed in children, bacterial cheilitis is similar to impetigo and is caused by streptococcal or staphylococcal type bacteria. It causes pus-filled blisters on the surface of the lips, which often develop into crusts. Bacterial cheilitis rarely confines itself to the lips and generally extends to the areas around the mouth, and even around the nostrils. The management of this infection is done with the help of local antiseptic treatments, coupled with antibiotic therapy, topical or systemic, for one to two weeks.

• Virulent Cheilitis.

  Virally induced cheilitis is primarily due to a recurrent infection by the herpes simplex virus (HSV1 or HSV2). It is characterised by clustered vesicles, located on the vermilion and adjacent skin. These vesicles progress to crusts and generally heal within about ten days. Local emollients are sufficient in most cases to halt the progression of viral cheilitis. If they are not effective enough, antivirals may be prescribed, such as aciclovir, valaciclovir or famciclovir.

• Fungal Cheilitis.

  Fungal or mycotic cheilitis is most often due to an infection by Candida albicans, a yeast naturally present in the oral cavity but which can become pathogenic following certain events, such as a decrease in immunity or prolonged antibiotic therapy. Fungal cheilitis resembles bacterial and viral cheilitis in its manifestation and causes vesicles on the lips, sometimes oozing. The application of an antifungal cream two to three times a day for two weeks is generally sufficient to curb the infection.

In the event of infected chapped lips, the first instinct should be to consult a doctor, so that they can determine the cause of the infection and prescribe an appropriate treatment.

Caustic cheilitis is an inflammatory reaction caused by the lips coming into contact with an irritating or corrosive substance, often found in household products. The lips then become red, swollen and painful. In the hours following the irritation, blisters may form, which then give way to crusts over a few days. The lesions from caustic cheilitis remain confined to the contact area. After such lip irritation, it is important to rinse them thoroughly and apply emollients in the following days to soothe the skin. In case of suspected ingestion or significant reaction, do not hesitate to consult a healthcare professional.

Exfoliative cheilitis, although relatively rare, involves severe and dramatic chapping, though it is not harmful. It is generally recognised by the thick brown scales it causes. According to an American study, women are more likely to be affected by exfoliative cheilitis, and it could be linked to psychiatric disorders, although this hypothesis is still under investigation. Indeed, the underlying mechanisms of exfoliative cheilitis are still not well understood. The management of this disorder includes frequent application of emollients, removal of crusts by a doctor, and in some cases, psychotherapy.

In some instances, chapped lips are the result of a medical treatment. Treatments with retinoids, such as isotretinoin, prescribed for severe or persistent acne, often lead to lip dryness, accompanied by flaking and redness. These molecules inhibit the proliferation of sebocytes and reduce sebum production, which is already low on the lips, causing them to dry out. Indinavir, a protease inhibitor used in patients suffering from the human immunodeficiency virus (HIV), has a similar action to that of retinoids, and can induce a similar form of cheilitis.

To prevent drug-induced cheilitis, a lip emollient is often prescribed in conjunction with a medication treatment that has drying effects.

There are numerous types of cheilitis that can affect the lips, each with specific causes and manifestations. The table below provides a non-exhaustive summary.