RT Book, Section A1 Lim, Henry W. A2 Goldsmith, Lowell A. A2 Katz, Stephen I. A2 Gilchrest, Barbara A. A2 Paller, Amy S. A2 Leffell, David J. A2 Wolff, Klaus SR Print(0) ID 56051779 T1 Chapter 92. Abnormal Responses to Ultraviolet Radiation: Photosensitivity Induced by Exogenous Agents T2 Fitzpatrick's Dermatology in General Medicine, 8e YR 2012 FD 2012 PB The McGraw-Hill Companies PP New York, NY SN 978-0-07-166904-7 LK accessmedicine.mhmedical.com/content.aspx?aid=56051779 RD 2024/04/23 AB |PrintAbnormal Responses to Ultraviolet Radiation at a GlancePhotosensitivity is broadly divided into phototoxicity and photoallergy, caused by topical or systemic agents that absorb ultraviolet A (UVA) energy.Phototoxicity occurs in anyone exposed to sufficient phototoxic agent and UV radiation and usually manifests as an exaggerated sunburn reaction.Photoallergy is an immune reaction to a UVA-modified chemical, commonly topical sunscreen agents and antimicrobials in the United States and the United Kingdom and topical nonsteroidal anti-inflammatory agents in Europe. It presents as eczematous eruption on sun-exposed areas.History taking is an important part of the evaluation; phototesting and photopatch testing are sometimes helpful.Differential diagnosis includes contact allergic or contact irritant dermatitis, airborne contact dermatitis, and other photodermatoses.Management consists of identification and avoidance of the precipitating agent, photoprotection, and symptomatic therapy.