Photoermatitis, or sometimes called by the nonscientific term sun poisoning, is a reaction of the skin to UV rays of the sun, or photoallergy. It may be caused by a medication that makes the skin more sensitive, a skin product (e.g. sunscreen containing PABA, certain fragrances), autoimmune conditions such as systemic lupus erythematosus (SLE) or a vitamin deficiency. Doctors can determine the presence of the disorder through a photo test.