The red marks that appear on the body upon scratching may be red bruises which are mainly characteristic of urticaria. Most likely, they are seen in chronic urticaria, especially artificial urticaria, where, through scratching later, mechanical stimulation leads to a degranulation reaction of subcutaneous mast cells. This inflammatory mediator, such as histamine, may stimulate the surrounding capillaries, resulting in peripapillary tissue congestion, and the formation of certain symptoms of irritation of peripheral nerves, and also produce certain itching symptoms. So when you encounter this situation, try to avoid scratching, and avoid skin extrusion. At the same time, you can temporarily apply topical glycolic lotion, and also need to take oral antihistamines to stop itching and control the occurrence of local wind clusters, you can take oral second-generation antihistamines, levocetirizine hydrochloride, ebastine, etc.