Atopic dermatitis, also known as eczema, is a common skin disease that affects about 20 percent of people worldwide. It usually begins early in life and resolves by age six. However, in many cases, the condition continues into adulthood.
The cause of this disease is not well understood, but it is known that individuals with atopic dermatitis often have other atopic diseases, including asthma, allergic rhinitis ("hay fever"), and food allergies.
The symptoms vary. In general, children have itching and red, scaly areas on the skin of the upper body, although it may occur anywhere on the body. Affected individuals are also at an increased risk for skin infections.
- Family or personal history of atopic diseases: A history of food allergy, hay fever, or asthma is associated with atopic dermatitis. About one-half of individuals with atopic dermatitis have a relative with asthma.
- Not being breast-fed: Some evidence suggests that exclusive breast-feeding for at least the first three months of life may be associated with a reduced risk.
Atopic Dermatitis: Diagnosis and Treatment
- A medical history and physical examination are the primary diagnostic tools.
- There are no laboratory tests that can definitively diagnose atopic dermatitis. Skin allergy testing may be useful, but is not required to make the diagnosis.
- Initial treatment involves eliminating factors that may worsen the disorder, such as soaps and detergents, food allergens, and cosmetics.
- Excessive bathing or use of lotions is discouraged, because evaporation of water from the skin worsens the disease. Many people are surprised to learn that water-based lotions actually increase evaporation of water from the skin, unlike emollient creams or ointments. Emollient creams or ointments should be applied liberally, especially after bathing, to lock in moisture. Humidifiers may be tried in dry climates.
- Antihistamines, such as diphenhydramine (Benadryl) or loratadine (Claritin) may relieve itching.
- Topical steroids may be used to treat active disease. Occasional use of topical steroids between episodes reduces the likelihood of recurrence. When severe flare-ups occur, oral steroids (e.g., prednisone) may be useful.
- Other medications, such as tacrolimus and cyclosporine, are sometimes prescribed for severe cases. However, these should be used carefully due to the risk of side effects, which may include skin cancer.
- Phototherapy using ultraviolet light is usually effective for treating severe disease, but may raise the risk for melanoma and other skin cancers.
Atopic Dermatitis: Nutritional Considerations
Nutritional changes to improve atopic dermatitis have been under study for many years. The following factors are under investigation:
- Avoiding alcohol during pregnancy: Maternal alcohol intake (four or more drinks per week) appears to significantly increase the risk for atopic dermatitis in infants. Further, alcohol use during pregnancy carries other major risks and should be avoided completely.
- Breast-feeding: Breast-feeding allows infants to minimize exposure to cow's milk proteins. However, cow's milk proteins may still be transferred via breast-feeding in mothers who drink milk. Avoidance of allergenic foods by a breast-feeding mother may further reduce risk of atopic disease in the infant.
In children who are not breast-fed, extensively hydrolyzed whey protein formulas have been used to reduce the risk of atopic dermatitis and are tolerated by at least 90 percent of infants with documented allergy to cow's milk protein. However, these formulas can still cause allergic symptoms. Only amino acid-based formulas can be considered completely nonallergenic.
- Delayed introduction of solid foods: Avoiding the introduction of solid foods until infants have reached four to six months of age appears to reduce the risk of atopic disease. A combination of breast-feeding (or hypoallergenic formula) and delayed introduction of solid food appears to be the most effective prevention in infants.
This approach may be further improved by minimizing environmental allergens. For example, polyvinyl mattress covers and anti-dust-mite sprays may be used. In a clinical trial, these combined steps were associated with a 67 percent reduction in dermatitis, compared with a control population.
- Eliminating allergy-causing foods: Eggs, cow's milk, soy, and wheat account for roughly 90 percent of the allergenic foods in children with atopic dermatitis. When these foods are avoided, more than 50 percent of children with diet-related atopic dermatitis experience a significant improvement in symptoms. When these foods are added back into the diet, symptoms may reappear, confirming their role in the disease process.
Adults with eczema are more likely to experience flare-ups when exposed to foods containing birch pollen, such as apples, carrots, celery, and hazelnuts. (See Rheumatoid Arthritis chapter for instructions on elimination diets.)
Double-blind, placebo-controlled food challenges have found that a small fraction of children and adults experience skin reactions when given various food additives. These include nitrite, benzoate, and tartrazine, balsam of Peru, and both natural and artificial vanilla. More than 50 percent of patients have been reported to improve on diets low in allergens.
- Vegetarian diets: Preliminary evidence indicates that a vegetarian diet results in significant improvements in symptoms. A low-calorie diet may also be helpful.
- Probiotic therapy: Prenatal treatment with Lactobacillus in mothers with a family history of atopic disease, combined with postnatal probiotic treatment of their infants, reduced the incidence of infant atopic dermatitis by 50 percent. Probiotic therapy also significantly reduced symptoms in infants and in children.
- Vitamin E: Preliminary data indicate that supplemental vitamin E (400 IU per day) improves symptoms in some adults with this disease.