Urticaria that does not go away after more than 24 hours may be related to changes in condition, insufficient dosage or course of treatment. 1. Changes in condition: Simple urticaria of the skin, with the appearance of wind, erythema and accompanied by itching. Generally this treatment can be prescribed oral loratadine tablets, ebastine tablets or levocetirizine tablets and other antihistamines. If the clamminess does not subside for more than 24 hours, it may be associated with urticarial vasculitis. 2. Insufficient dosage or course of treatment: If the patient does not take enough dosage or insufficient course of treatment, it can also lead to urticaria for more than 24 hours and still not go away. You need to increase the dosage or change other drugs under the advice of your doctor. Hives for more than 24 hours does not go away can also be caused by other reasons. If you experience significant discomfort, you should go to a regular hospital immediately to find out the cause and follow the doctor’s instructions.