This Publication Is Searchable The Merck Manual of Diagnosis and Therapy Section 10. Dermatologic Disorders Chapter 119.
Solar urticaria develops at a site of sun exposure within a few minutes.
If large cutaneous areas are exposed for longer intervals, syncope, dizziness, wheezing, and other systemic symptoms may develop. Solar urticaria can be classified into six types based on the UV action spectrum and results of passive transfer and reverse passive transfer tests. Numerous factors, many unknown, may contribute to photosensitivity. Unless the cause is obvious, every patient with pronounced photosensitivity should be evaluated for systemic or cutaneous lupus erythematosus. Xeroderma pigmentosum and certain porphyrias can also lead to photosensitivity.