Photo allergy
| Sun poisoning | |
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| An image of a patch of sun poisoning on the left forearm | |
| Specialty |
Dermatology 
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| Classification |
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Photodermatitis, sometimes referred to as sun poisoning or photoallergy, is a form of allergic contact dermatitis in which the allergen must be activated by light to sensitize the allergic response, and to cause a rash or other systemic effects on subsequent exposure. The second and subsequent exposures produce photoallergic skin conditions which are often eczematous. It is distinct from sunburn.
Photodermatitis may result in swelling, difficulty breathing, a burning sensation, a red itchy rash sometimes resembling small blisters, and peeling of the skin. Nausea may also occur. There may also be blotches where the itching may persist for long periods of time. In these areas an unsightly orange to brown tint may form, usually near or on the face.
Many medications and conditions can cause sun sensitivity, including:
Photodermatitis can also be caused by plants like the Dictamnus (commonly known as the "Burning Bush"), a genus of flowering plant in the Rutaceae family. This is called phytophotodermatitis.
Prevention includes avoiding exposure to chemicals that can trigger the reaction, such as by wearing gloves, or avoiding sunlight or wearing sunscreen preferably with at least factor 30 and with a high UVA protection level on the affected area.
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Wikipedia