Chapter 3. Introduction
An important feature of atopic dermatitis is so-called "skin hyperreactivity." This refers to a common problem that changes in the environment can trigger patients with atopic dermatitis to start feeling itchy and set off the itch-scratch cycle that leads to a flare of eczema. This is not unlike the airway hyperreactivity that leads to wheezing in asthmatics or nasal hyperresponsiveness that leads to sneezing in hay fever. Indeed often times the same patients can have all three diseases reflecting a general tendency to react adversely to the environmental factors which appear innocuous to nonatopic healthy individuals.
A number of factors can trigger eczema or atopic dermatitis including dry skin, irritants, foods, aeroallergens and infection (TABLE A).
Atopic dermatitis is often called the "itch that rashes." This is because exposure to triggers often causes the patient to feel a sensation of itch, but it is not until the patient scratches their skin that the rash actually appears. Eliminating known triggers of eczema is therefore an important part of managing eczema because the more a patient scratches the worse their eczema will become.