In most cases of chronic urticaria, an underlying trigger is not found. Hodgkin's disease may be accompanied by urticaria. Cold urticaria with cryoglobulinemia is seen in multiple myeloma.

在大多数麻疹患者，找不到触发原因。霍杰氏病可伴有麻疹；冷球蛋白血的麻疹见于多发骨髓瘤。