Why protect your lips from UV radiation?

The lips are among the most sensitive areas of the face, including to ultraviolet radiation.

This vulnerability stems from their unique anatomical structure: unlike skin elsewhere, lip mucosa lacks a thick stratum corneum and contains few keratinocytes and melanocytes. The lips contain little melanin, the protective pigment produced after sun exposure. This explains why lips do not tan and remain vulnerable to sun damage. Moreover, lip skin has few sebaceous glands, the organs that produce sebum. It lacks a hydrolipidic film, the protective layer of water, sweat, and sebum covering the rest of the body. That is why lips dry and become sensitive to external stressors, including ultraviolet radiation.

Although UV rays are not the sole cause of lip cancers, they are a significant contributing factor. This is true for people working outdoors, such as roofers, farmers, sailors, and horticulturists. Protecting the lips from the sun is therefore more than a comfort measure: it is a public health action that can prevent serious lesions.

Chronic exposure to ultraviolet rays promotes the development of actinic cheilitis. This precancerous lesion, called lip actinic keratosis, results from the abnormal proliferation of keratinocytes after repeated sun exposure. Symptoms vary: dryness, scaling, erythema, atrophy, even ulceration. Over time, these lesions can progress to invasive squamous cell carcinoma, an aggressive lip cancer with prognosis that worsens as diagnosis is delayed. Precancerous lip lesions may go unrecognised due to lack of information.

Protecting the lips from UV exposure is essential to prevent cancerous lesions.

Several studies have highlighted the importance of photoprotection. Research in Brazil with 404 adults showed a 47.1 % prevalence of actinic cheilitis in the population, in individuals exposed to sunlight for more than four hours per day. In these participants, using physical protection such as a broad-brimmed hat, with or without sunscreen, was associated with a significant 33 % reduction in the risk of actinic cheilitis. This study underscores the need for lip sun protection, a neglected area. Despite this, a separate survey of 119 beach workers in Brazil found that 7.5 % used a lip balm with SPF and fewer than one third applied body protection. These figures reveal a concerning lack of awareness of sun risks for the lips.

Several products are now formulated specifically to protect the lips from sun exposure. Most come as sunscreen sticks or lip balms enriched with SPF, but it is possible to find lip-specific sunscreens. These products form a protective film against UV rays, and their rich texture limits water loss from the lip surface. In addition, the advantage of sunscreen sticks and lip balms lies in their portable format, easy to slip into a pocket or bag, which encourages application throughout the day. Sun protection must be reapplied regularly, including after meals.

Choosing a lip balm or sunscreen stick with an SPF of at least 30 is a simple measure to preserve lip suppleness and reduce the risk of precancerous lesions such as actinic cheilitis.

• VARVAKI RADOS P. & al. Sun protection as a protective factor for actinic cheilitis: cross-sectional population-based study. Oral diseases (2022).

• DE CAMPOS L. & al. Prevalence of and risk factors for actinic cheilitis in Brazilian beach workers. Journal of Dental Health, Oral Disorders & Therapy (2022).

• HAFSI W. & al. Cheilitis. StatPearls (2023).

• DA SILVA MARCELINO P. & al. In vitro photoprotection and functional photostability of sunscreen lipsticks containing inorganic active compounds. Cosmetics (2023).