Photosensitivity can lead to a chronic skin condition called Photodermatoses characterised by a rash in a sun-exposed distribution following sun exposure, the rash can become erythematous (red) and inflamed . Certain chemicals, materials and medications act as photosensitisers triggering a photosensitive reaction referred to as Photodermatitis – which is essentially an allergic reaction to a chemical or substance activated by the sun