Diagnostic Approach to Food Allergy in Atopic Dermatitis

Introduction to Diagnostic Approach

The American Academy of Dermatology recommends a diagnostic food elimination diet followed by oral food challenge if improvement occurs, as the best approach to diagnose food allergy in a patient with atopic dermatitis not responding to topical steroids 1, 2

Skin prick testing and food-specific IgE have poor positive predictive value (40-60%) and only indicate sensitization, not true food allergy, according to the American Academy of Dermatology 3, 4, 5
The American Academy of Dermatology states that 50-90% of presumed food allergies based on symptoms or positive tests are not true allergies 6, 7

The American Academy of Dermatology recommends an elimination diet for 4-6 weeks with suspected food items, if consistent correlation between food exposure and dermatitis flares exists 1, 2
In children <5 years with moderate-to-severe AD not responding to optimized therapy, the American Academy of Dermatology suggests considering testing cow's milk, eggs, wheat, soy, and peanut 5

An oral food challenge under allergist guidance is essential to confirm the diagnosis, as improvement may be coincidental or placebo effect, according to the American Academy of Dermatology 1, 2, 4
The American Academy of Dermatology recommends double-blind placebo-controlled food challenge as the gold standard, though open-label challenges are acceptable in clinical practice 4, 5

Food allergies are relevant triggers in only a small subset of AD patients (usually moderate-to-severe disease), and excessively restrictive diets can cause weight loss, poor growth, calcium deficiency, hypovitaminosis, and kwashiorkor, warns the American Academy of Dermatology 1, 2
The American Academy of Dermatology advises against basing elimination diets on positive skin tests or IgE alone without clinical correlation, as positive tests only indicate sensitization; clinical relevance must be established 1, 2, 3