Photosensitivity
Pronunciation: foh-toh-sen-sih-TIV-ih-tee
An abnormal skin reaction to ultraviolet or visible light, producing rash, erythema, or blistering at sun-exposed sites.
Full Definition
Photosensitivity in dermatology denotes an exaggerated or abnormal cutaneous response to electromagnetic radiation, particularly ultraviolet A (UVA) and B (UVB) wavelengths. It may be endogenous (as in systemic lupus erythematosus or porphyria) or exogenous (phototoxic or photoallergic reactions triggered by drugs, plants, or cosmetics). Editors must distinguish between phototoxic reactions (dose-dependent, no immune mechanism) and photoallergic reactions (immune-mediated, require prior sensitisation), as the two are not interchangeable in clinical copy. The term is written as one unhyphenated word.
Usage
Usage note: Do not use 'photosensitivity' as a synonym for 'phototoxicity' or 'photoallergy'; these are distinct mechanisms and should be named precisely in clinical documents.
In Context
- "Photosensitivity was documented as a drug reaction to the patient's newly commenced hydrochlorothiazide." — Adverse drug reaction report
- "The document conflated 'phototoxicity' and 'photosensitivity'; the editor added a clarifying distinction in a footnote." — Editorial query