Immediate-type allergy, also known as type I hypersensitivity, is a condition in which the immune system overreacts to harmless substances, such as pollen or food, and triggers an allergic reaction. This medical term can be substituted with other synonyms, such as anaphylaxis, acute allergic reaction, or IgE-mediated hypersensitivity. Anaphylaxis is a severe and potentially life-threatening form of immediate-type allergy, while acute allergic reaction refers to a rapid onset of symptoms. IgE-mediated hypersensitivity refers to the involvement of immunoglobulin E antibodies in the allergic response. It is important to use these synonyms correctly to ensure accurate communication between healthcare providers and patients about their condition and treatment options.