If the bumps disappear at night and disappear during the day, and if they do not leave any traces afterwards, urticaria is likely to be considered. Urticaria can subside on its own within 24 hours, but the rash can be recurrent and accompanied by a pronounced itching sensation, and the rash can appear as a flat, wind-like rash or sometimes as an erythema. Urticaria is an allergic reaction. For those who have a rash at night, you need to pay attention to whether there is an allergic reaction to dust mites or bedding, or some patients may have flowers in their bedrooms, which may also trigger an allergic reaction to pollen and trigger an attack of urticaria at night. For those who have a large rash, two antihistamines can be taken orally alternately, and the medication can be continued for 3 days after the rash has completely subsided.