Sensitized

Sensitized is the past participle of the verb sensitize, meaning made more sensitive or reactive to a stimulus. The term is used across disciplines to describe a change in responsiveness that results from exposure, conditioning, chemical modification, or prior experience. In medicine and immunology, sensitization refers to the process by which an individual becomes reactive to a substance, such as an allergen. After initial exposure, the immune system can develop memory, and subsequent contact may trigger allergic reactions or hypersensitivity.

In psychology and neuroscience, sensitization denotes an increased behavioral or physiological response to a stimulus after repeated exposure, contrasting with habituation. This heightened responsiveness can involve changes in neural circuits or receptor function and can influence how stimuli are perceived and acted upon. In pharmacology and toxicology, drug sensitization describes heightened reactions to a substance after prior use, which can affect tolerance, efficacy, and risk of adverse effects.

In chemistry and materials science, sensitization refers to chemical or physical processes that increase a substance’s responsiveness to light, heat, or other stimuli. For example, sensitizers in photographic emulsions extend light sensitivity to different wavelengths, while surface or tissue sensitization in various industrial contexts aims to improve bonding or reactivity.

The term is widely used as an adjective, with examples such as a sensitized patient, tissue, or material. See also hypersensitivity, conditioning, and sensitization in immunology for related concepts.