What Conditions Are Related to Atopic Dermatitis?
The underlying factors that cause atopic dermatitis (AD) also put a person at a greater risk of developing other related conditions, including asthma, hay fever, and food allergies.
What is atopy?
The word “atopy” means a genetic disposition to develop an allergic reaction and produce elevated levels of immunoglobulin E (IgE) when exposed to an environmental allergen.
What is immunoglobulin?
Immunoglobulin is a type of protein that is part of the immune system and that acts as an antibody to attach and destroy foreign substances. There are five different types of immunoglobulin, and the IgE protein is found in increased levels in people with allergy. IgE causes the body to release histamine when it comes into contact with an allergen.1,2
Doctors have coined the term “atopic march” to describe the progression of allergic diseases that is frequently seen in people who have atopic dermatitis in childhood and who later develop these other allergic conditions. Some people who have AD in childhood outgrow the disease, and it goes into remission. Scientists do not currently understand the exact mechanisms behind how some people “outgrow” the condition, but believe there may be both genetic and environmental explanations.3
Children with AD are at an increased risk of developing asthma, a chronic condition of the lungs that involves inflammation of the airways after exposure to a trigger. Asthma makes it difficult to get air in and out of the lungs and can cause symptoms such as wheezing, coughing, shortness of breath, and tightness of the chest.3,4
How many people have asthma in addition to eczema?
The main risk factors for progression of AD to asthma are the presence of IgE in response to exposure to allergens (called IgE sensitivity), early onset of AD, and the severity of AD. Approximately 70% of children with severe AD develop asthma, compared to 20-30% of children with mild AD.4
Allergic rhinitis or hay fever
AD also puts a person at a higher risk of developing hay fever, or allergic rhinitis. Contrary to its name, hay fever does not cause a fever. Its symptoms include runny and/or stuffy nose, sneezing, fatigue, and itchy eyes, mouth, or skin. Hay fever may be seasonal, with a flare in symptoms due to allergic sensitivity to airborne mold spores or pollens, or perennial, with symptoms year-round due to sensitivity to pet dander, mold, dust mites, or cockroaches. The risk factors for a child with AD developing hay fever are the severity of AD and the elevated levels of IgE in their blood.3,4
Some children with AD develop food allergies. A person with a food allergy has a rapid reaction (within 30 minutes of exposure) to a particular food. Symptoms may include hives and itching of the lips. A severe reaction includes respiratory, gastrointestinal, or anaphylaxis (an acute allergic reaction that requires immediate medical attention as it can lead to severe swelling of airways, lowered blood pressure, or shock).5,6
How common are food allergies for children with eczema?
The risk of developing food allergies seems to be greater in children who developed AD before the age of 6 months, as well as those with more severe AD and elevated levels of IgE. Common food allergies include milk, egg, peanut, wheat, and soy. The American Academy of Dermatology recommends children less than 5 years of age with moderate to severe AD should be considered for food allergy evaluation if they have persistent AD in spite of topical treatment and proper skin care management or if they have a history of an immediate reaction after ingesting a specific food.5,6