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were also photopatch tested with the carprofen agents and none had a positive reaction. We believe that these reactions are due to photoallergy rather than photoxicity because the problem took 3 weeks to develop, she demonstrated strong photopatch testing reactions at three different concentrations of carprofen, all of which were well below the 5% used in previous studies, no other workers were affected and no controls reacted. Carprofen is a propionic acid derivative and was developed for human use but was not launched on the U.K. or U.S. markets. It was subsequently marketed for the management of canine arthritis. One case of canine photosensitivity was reported to the U.S. Food and Drug Administration in 1997. This group of NSAIDs are the commonest NSAIDs that cause photosensitivity from topical and systemic use and include ibuprofen, ketoprofen and benoxaprofen (Opren ), which was withdrawn from the U.K. market in 1982. She had taken ibuprofen purchased over the counter without any problems in the past. Carprofen, unlike other propionic acid derivatives, undergoes photodehalogenation rather than photodecarboxylation, which would make a cross-reaction due to previous exposure to another NSAID such as ibuprofen unlikely. Photodehalogenation results in the formation of an aryl radical. This has a potent effect on lipids, which has been demonstrated experimentally by the photoperoxidation of linoleic acid by carprofen. There have been numerous reports of photosensitivity caused following ingestion of carprofen by humans, some of which were felt to be photoallergic. It has not previously been reported as an occupational contact photoallergen and it seems likely that contact occurred following transfer of the carprofen from her protective clothing on to her skin while changing back into her everyday clothes. It is important that precautions are taken to avoid potential allergens while handling them in the workplace and this case highlights the need for employers and their employees to be vigilant that allergens do not cause problems following transfer on to the skin during the removal of protective clothing.