Eczema on the lips, medically known as eczematous cheilitis or lip dermatitis, is an inflammatory condition causing persistent redness, dryness, scaling, and cracking of the lips and surrounding skin. This condition is often chronic and painful, going beyond typical chapped lips. The skin on the lips is distinctively delicate; its outermost protective layer (stratum corneum) is significantly thinner than skin elsewhere on the body. Lacking oil glands, the lips cannot naturally produce moisture, making them highly susceptible to external damage and inflammation.
Irritants and Environmental Damage
One of the most common causes of lip eczema is direct physical damage to the skin barrier, known as irritant contact cheilitis. This is frequently initiated by lip-licking, which creates a cycle of wetting and drying that removes the protective oily surface layer. Saliva is particularly damaging because it contains digestive enzymes like amylase and lipase, which break down the exposed skin barrier and cause inflammation. Chronic physical trauma, such as habitual lip biting or sucking, can also lead to this irritation.
Environmental factors play a substantial role, as harsh weather, including cold, wind, and low humidity, accelerates moisture loss from the lips. This moisture loss often prompts the urge to lick them. Contact with non-specific chemical irritants can also contribute to the breakdown of the barrier. Strong ingredients in oral care products, such as aggressive foaming agents in toothpaste or mouthwash, and highly acidic foods can directly irritate the thin lip tissue.
Allergic Contact Reactions
In contrast to direct irritation, allergic contact cheilitis is an immune-mediated hypersensitivity reaction, where the body’s immune system responds to a specific substance as a threat. This delayed-type immune response can manifest as eczema on the lips hours to days after exposure to the allergen. Identifying the cause can be challenging because the reaction is not immediate, requiring diagnostic tools like patch testing to confirm the trigger.
Many common allergens are found in lip products, including fragrances, flavorings, and preservatives. Flavoring agents, particularly those derived from Balsam of Peru, cinnamon, or vanilla, are frequent culprits found in lip balms, toothpaste, and chewing gum. Preservatives like parabens and formaldehyde-releasers, along with ingredients like lanolin or specific dyes, can also provoke an allergic response.
Metals can be a source of lip allergy, particularly nickel, transferred from musical instruments, jewelry, or metal casings of some lip products. Transfer allergens are another significant category, where a substance is unintentionally moved to the lips, such as from handling nail polish containing acrylates or using fragranced hand creams. Foods, especially citrus fruits or cinnamon, can also act as allergens, causing localized cheilitis upon contact.
Internal and Systemic Predispositions
Some cases of lip eczema stem from underlying health conditions or internal factors, rather than contact with external substances. The strongest internal link is to Atopic Dermatitis, an inherited tendency toward eczema, asthma, and hay fever. Individuals with this predisposition have a genetically weakened skin barrier function, making their lips inherently more vulnerable to inflammation and irritation, even when the external trigger is mild.
Nutritional deficiencies can also predispose the lips to eczema, particularly deficiencies in certain vitamins and minerals necessary for skin health and repair. A lack of B vitamins, such as riboflavin (B2), can contribute to inflammation and cracking, especially at the corners of the mouth, a condition known as angular cheilitis. Deficiencies in minerals like iron and zinc are also associated with chronic lip irritation and inflammation.
Underlying systemic inflammatory conditions or issues affecting nutrient absorption, such as Crohn’s disease or celiac disease, can indirectly manifest as chronic lip inflammation. Chronic mouth breathing, often due to nasal congestion, can also contribute to dryness that initiates the cycle of irritation and inflammation, making the lips more vulnerable to developing eczematous changes.