Drug fever is classified as which type of hypersensitivity reaction?

Drug fever is classified as a Type III hypersensitivity reaction. This type of hypersensitivity occurs when immune complexes formed by antibodies interacting with soluble antigens deposit in various tissues, leading to an inflammatory response. This process can activate complement and recruit inflammatory cells, ultimately resulting in fever as a systemic manifestation.

In the context of drug fever, medications can act as haptens, binding to proteins and forming new antigens that provoke an immune response. The presence of these immune complexes can stimulate the release of pro-inflammatory mediators, causing fever and other systemic symptoms.

While other types of hypersensitivity reactions have distinct mechanisms and clinical presentations—like Type I (immediate hypersensitivity), Type II (cytotoxic reactions), and Type IV (delayed-type hypersensitivity)—Type III is specifically associated with immune complex-mediated inflammation, making it the correct classification for drug fever.