Atopic dermatitis, commonly known as eczema, is a chronic inflammatory skin condition involving complex interactions among genetics, environment, immune system function, and lifestyle habits. Recent studies indicate that the pathogenesis of eczema is closely related to abnormalities in skin barrier function, immune system hyperreactivity, and interactions with external stimuli. Understanding these key factors and their interplay helps patients and their families develop more effective prevention and treatment strategies.
Modern medicine summarizes the causes of eczema into three core elements: genetic susceptibility, environmental triggers, and immune regulation abnormalities. Congenital defects in the skin barrier allow allergens and irritants to penetrate more easily, thereby triggering an overreaction of the immune system. This multifactorial interaction pattern necessitates a comprehensive approach to analyzing the causes of eczema.
Genetic factors play a crucial role in the development of eczema. Scientific research shows that if there is a family history of allergic rhinitis, asthma, or eczema, the risk of offspring developing the condition significantly increases. Among these, Filaggrin gene mutations are the most extensively studied genetic factors. This gene is responsible for producing proteins that maintain skin barrier integrity. When this gene is defective, water retention in the skin decreases, making it more susceptible to bacterial or allergen infiltration, leading to inflammatory responses.
Besides the Filaggrin gene, other genes related to immune regulation (such as TH2 cell-related genes) are also believed to be associated with eczema. These genes influence how the immune system responds to external stimuli, making genetically susceptible individuals more prone to exaggerated immune reactions upon exposure to environmental triggers.
Environmental irritants are key external factors that trigger or exacerbate eczema. Climate changes, contact with chemicals, and microbial infections can directly damage skin barrier function, thereby inducing inflammatory responses. For example, cold and dry environments accelerate water evaporation from the skin, causing the stratum corneum to dry and crack, creating entry points for pathogens.
Common allergens in the environment include dust mites, pollen, and pet dander. These allergens interact with skin barrier defects to trigger IgE-mediated allergic reactions. Chemical irritants such as surfactants in cleaning products, fragrances in cosmetics, and industrial solvents can directly damage the lipid structure of the stratum corneum, impairing skin barrier function.
Lifestyle habits significantly influence the frequency and severity of eczema flare-ups. Improper skin care, such as excessive use of hot water for cleansing or frequent exfoliation, can damage the already fragile skin barrier. Modern stress management deficiencies may also disrupt neuroendocrine regulation, promoting a vicious cycle of inflammation.
Dietary factors vary between adult and pediatric patients. Children may experience acute flare-ups due to food allergies such as milk or eggs, while adults are more often triggered by alcohol or spicy foods. However, not all patients react directly to specific foods; allergy testing is recommended for confirmation.
Age factors show that early childhood is a high-risk period for eczema, as infant skin's stratum corneum is still developing, and barrier function is relatively weak. Regarding gender differences, studies suggest that females have a slightly higher incidence after puberty, possibly related to hormonal changes. Occupational exposure risks include healthcare workers handling disinfectants or hairdressers frequently exposed to chemical dyes.
Living environment hygiene also influences disease risk. The “hygiene hypothesis” suggests that microbial exposure during early childhood helps immune system maturation, whereas overly sanitized environments may increase allergic disease risks. Additionally, urban air pollutants like PM2.5 particles have been shown to induce oxidative damage to skin lipids.
The causes of eczema are characterized by multifactorial interactions, with genetic predisposition as the main foundation, environmental triggers as key catalysts, and individual immune status determining the severity of the disease. Modern medical perspectives emphasize that effective management should involve improving skin barrier function, avoiding known triggers, and regulating immune responses simultaneously. Patients should keep detailed symptom diaries to track personal triggers and develop personalized management plans in consultation with healthcare professionals.
Environmental factors such as dry climate, high temperature with sweating, or contact with chemical irritants (like detergents or fragrances) can worsen eczema symptoms. If symptoms recur under certain conditions (e.g., drier skin in winter or itching after contact with pet fur), it is recommended to keep a symptom diary and try to avoid or reduce exposure to suspected triggers to observe if symptoms improve.
Are there side effects of using steroid ointments?Proper use of low to moderate potency steroid ointments is generally safe, but it is essential to follow medical advice regarding duration and dosage. Long-term overuse may cause skin thinning or vascular dilation, but short-term treatment effectively controls inflammation. The benefits and risks should be evaluated by a physician. Non-steroidal anti-inflammatory ointments (such as calcineurin inhibitors) are also alternatives.
What is the "itch-scratch cycle"? How can it be avoided?The itch-scratch cycle occurs when eczema-related skin dryness causes itching, leading to scratching, which damages the skin, causes redness, swelling, and even infection, perpetuating the cycle. It is recommended to use cold compresses, thick moisturizers, and wear cotton clothing to reduce itching, avoid scratching, and keep the skin well-moisturized to minimize irritation.
What is the relationship between infant eczema and allergic diseases?Infants with eczema often have an “atopic phenotype,” which increases the risk of food allergies (such as milk or peanuts), asthma, and allergic rhinitis. This association is known as the “atopic march,” but not all patients develop other allergies. Regular skin care and allergy testing can help manage the condition.
How do natural and chemical moisturizers differ and how to choose?Natural moisturizers (like shea butter and coconut oil) provide hydration but may contain allergens; chemical moisturizers (like urea and lactic acid) effectively repair the skin barrier. It is recommended to choose products free of fragrances and preservatives, perform patch tests before use, and select products suitable for individual skin types.
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