Allergies are a common experience, affecting millions with symptoms from sneezing and itchy eyes to severe reactions. These occur when the immune system overreacts to harmless substances like pollen or dust. For lasting relief, therapies involving gradual exposure to triggers aim to modify the body’s response.
Understanding Allergen Immunotherapy for Allergies
When considering “exposure therapy” for allergies, the medical term is allergen immunotherapy, also known as desensitization or hypo-sensitization. This treatment differs from psychological exposure therapy, used for conditions like phobias. Allergen immunotherapy focuses on physiological responses to substances that trigger allergic reactions. Its goal is to gradually reduce sensitivity to allergens, decreasing symptom severity.
How Allergen Immunotherapy Alters the Immune Response
Allergen immunotherapy works by inducing specific changes within the immune system to foster tolerance. A primary mechanism involves a shift in antibody production, moving away from a strong IgE (immunoglobulin E) response, which is responsible for immediate allergic reactions. Instead, it promotes an increase in protective IgG (immunoglobulin G) antibodies, particularly IgG4. These IgG antibodies can act as “blocking” antibodies, intercepting allergens before they trigger the allergic cascade.
The therapy also promotes the generation of specialized immune cells called T-regulatory (Treg) cells. These cells play a significant role in suppressing the allergic inflammatory response and inducing peripheral tolerance to allergens. Immunotherapy can also lead to an early desensitization of mast cells and basophils, which are cells that release histamine and other chemicals responsible for allergic symptoms.
The Treatment Process and Its Duration
Allergen immunotherapy begins with an allergist’s evaluation to identify specific triggers. The two main forms are subcutaneous immunotherapy (SCIT), or allergy shots, and sublingual immunotherapy (SLIT), involving drops or tablets under the tongue. SCIT involves weekly injections during a “build-up” phase, gradually increasing the allergen dose over three to six months. Patients then enter a “maintenance” phase, receiving injections every two to four weeks. SLIT is often taken daily at home after an initial supervised dose.
Immunotherapy is a long-term commitment, often lasting three to five years for lasting benefits. While some notice improvement within six to twelve months, full benefits typically appear after a year on the maintenance dose. Consistent adherence is important for successful outcomes. Medical supervision is required throughout the process, especially during the build-up phase, to monitor for reactions.
Who Benefits from Allergen Immunotherapy?
Allergen immunotherapy suits individuals with allergic conditions not adequately controlled by medications or avoidance. It is commonly recommended for allergic rhinitis (hay fever), allergic asthma, and stinging insect allergies. The treatment significantly reduces symptoms and often decreases the need for allergy medications. For children with allergic rhinitis, immunotherapy may also help prevent asthma development.
Most people experience significant symptom improvement, with reported benefits ranging from 80% to 90%. Success depends on patient adherence and the specific allergens involved. While highly beneficial for environmental and insect venom allergies, it is not a standard treatment for most food allergies, where avoidance remains the primary strategy.