Multi-Centre European Photopatch Test Study

It is known that people can develop an allergic skin reaction to a substance which is placed on the skin and then subjected to sunlight. This process is called Photocontact allergic dermatitis. It is known that people can develop Photocontact allergic dermatitis to sunscreen chemicals (filters) and also cream forms of pain-killing drugs called nonsteroidal anti-inflammatory drugs (NSAIDs). The purpose of this study is to determine the frequency of Photocontact allergic dermatitis to 19 sunscreen filters and 5 topical NSAIDs in 1,000 European patients who present to a dermatologist with a sun-exposed site dermatitis. Each participant will have the 24 test agents plus one control of petrolatum applied to the skin of the back for 24 or 48 hours. After removal of the substances, the area of skin will be exposed to a precise amount of ultraviolet-A light. The area is then assessed 24, 48 and 72 hours later to see if a photocontact allergic reaction has occured. This method is known as photopatch testing. The study will run for one year, during which time it is planned to recruit 1,000 patients.