What Causes Allergies? Ask the Chatbot a Question More Actions Share Share Share to social media Facebook X URL https://www.britannica.com/science/What-Causes-Allergies Feedback Corrections? Updates? Omissions? Let us know if you have suggestions to improve this article (requires login). Feedback Type Select a type (Required) Factual Correction Spelling/Grammar Correction Link Correction Additional Information Other Your Feedback Submit Feedback Thank you for your feedback Our editors will review what you’ve submitted and determine whether to revise the article.

　　External Websites Ask the Chatbot a Question Written and fact-checked by The Editors of Encyclopaedia Britannica Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. They write new content and verify and edit content received from contributors. The Editors of Encyclopaedia Britannica Last Updated: Mar 4, 2025 • Article History Table of Contents Table of Contents Ask the Chatbot Allergic reactions are caused by substances known as allergens. These substances can be found in a variety of sources such as pollen, mold spores, dust, animal dander, and certain foods. These substances induce the hypersensitive state of allergy and stimulate the formation of reaginic antibodies, eading to the release of chemicals like histamine, which cause the symptoms associated with allergies, such as sneezing, itching, and swelling. The immune system plays a crucial role in the development of allergies. It contains specialized white blood cells called lymphocytes, which include B cells and T cells. B cells are responsible for producing antibodies ...(100 of 258 words)

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