 Patients prescribed 50 milligrams four times per day have been able to sustain normal exposure to the sun without suffering a reaction.Patients with less potent forms of solar urticaria such as fixed solar urticaria can be treated with the medication fexofenadine, which may also be used prophylactically to prevent recurrence.This form of treatment is meant to reduce the intensity or altogether eliminate the allergic reactions people have by gradually increasing exposure to the form of radiation that brings about the reaction.