How is an allergy defined?

An allergy is defined as a hypersensitive state acquired through exposure to allergens. This means that when the immune system encounters a typically harmless substance, known as an allergen, it responds excessively, leading to an allergic reaction. This process involves the production of specific antibodies—such as IgE—that trigger various symptoms, which can range from mild (like sneezing and itching) to severe (such as anaphylaxis). Understanding this definition is crucial, as it differentiates allergies from other immune responses or conditions, emphasizing that an allergy is specifically the result of an unusual immune reaction to a substance that is normally tolerated by most people.

In contrast, a normal immune response typically does not involve such an exaggerated reaction and serves to protect the body from harmful pathogens. Similarly, autoimmune conditions occur when the immune system mistakenly attacks the body's own tissues, which is distinct from the concept of allergies. Additionally, while food sensitivities may share some similarities with allergies, they generally involve responses that are not immune-mediated and often do not involve the same specific immune protocols, such as antibody production. Recognizing these distinctions helps clarify the precise nature of allergies and their implications for health.