Eczema, formally known as atopic dermatitis, is a common chronic inflammatory skin condition characterized by an intensely itchy, dry, and often red rash. This condition frequently occurs alongside other allergic diseases, such as hay fever and asthma. Allergy Immunotherapy (AIT), often administered as “allergy shots,” is a long-term treatment designed to modify the body’s immune response to specific environmental allergens like pollen, dust mites, or pet dander. A common question is whether allergy shots can initiate or worsen a person’s eczema.
Understanding Allergy Immunotherapy
Allergy Immunotherapy works by gradually exposing the immune system to increasing doses of the substance a person is allergic to. This process induces immune tolerance, retraining the body to stop reacting aggressively to the allergen. The treatment typically involves a build-up phase with frequent, increasing doses, followed by a maintenance phase with less frequent injections over three to five years. AIT encourages the production of protective antibodies, particularly Immunoglobulin G (IgG), which act as “blocking antibodies” to intercept the allergen. Simultaneously, the treatment influences T-cells, shifting the immune system toward a more regulatory response to reduce the severity of allergic symptoms long-term.
The Known Relationship Between AIT and Eczema
Current medical consensus suggests that Allergy Immunotherapy does not cause new cases of eczema. For patients whose eczema is closely linked to specific environmental allergens, AIT may offer a beneficial long-term effect on skin health. However, starting AIT, especially during the initial build-up phase, can sometimes lead to a temporary flare of pre-existing eczema. This temporary exacerbation is thought to be an acute reaction as the immune system processes the newly introduced allergen extract. Clinical studies show that while AIT carries a risk of adverse events, it often leads to significant improvement in the severity of atopic dermatitis and the patient’s quality of life, particularly for those allergic to house dust mites.
Distinguishing Common AIT Reactions from Eczema
It is important to differentiate between a chronic eczema flare and the expected side effects of the immunotherapy injection itself. The most frequent reaction is a local reaction at the injection site, including redness, swelling, and itching that usually resolves within a few hours. Less common are mild systemic reactions occurring shortly after the injection, such as hives (urticaria), sneezing, or minor upper respiratory symptoms. While hives are a skin reaction, they appear as raised, pale red welts and are distinct from the dry, scaling, and intensely itchy patches characteristic of chronic eczema. These acute systemic reactions are temporary and are managed by the prescribing physician, often through dose adjustment.
The Atopic March and Long-Term Effects
Eczema is often the first manifestation in a common progression of allergic diseases referred to as the “Atopic March.” This sequence typically begins with eczema in infancy, followed by the development of food allergies, and then progresses to allergic rhinitis (hay fever) and asthma later in childhood. The damaged skin barrier in eczema is thought to contribute to this progression by allowing allergens to enter the body and sensitize the immune system. A primary long-term benefit of AIT is its potential to modify this natural history of allergic disease. By inducing immune tolerance, the therapy may help prevent the development of new allergic conditions, such as asthma, in children who have allergic rhinitis, leading to sustained improvement in eczema severity and quality of life.