Patients with itchy skin after sweating, and red rash, the main causes are as follows: 1. Cholinergic urticaria: In the summer due to strenuous exercise, heat, emotional stress, after eating hot drinks, the body appears red and itchy, consider cholinergic urticaria. This is mainly due to the allergic reaction caused by the rise of temperature in the deep part of the torso after strenuous exercise, which prompts acetylcholine to act on mast cells. It can appear on the body as a wind cluster, accompanied by itching, flushing of the skin, and in severe cases, headache, abdominal pain, and diarrhea. Mild cases will subside within an hour. Frequent cases need to be treated by giving levocetirizine hydrochloride tablets and ketotifen tablets to be taken orally at the same time. For topical application, patients can apply a mixture of mometasone furoate cream and urea vitamin E cream topically. During the treatment period, it is necessary to abstain from spicy and irritating food and alcohol, while maintaining a happy mood, avoiding excessive emotional tension, and avoiding strenuous exercise as much as possible. 2. contact dermatitis: after the patient sweats, the dust mites of the air cause an allergic reaction to the skin, and it is recommended to go to the dermatology department for allergen screening. For itchy skin and rashes after sweating, it is recommended that patients go to a regular hospital and be treated under the guidance of a dermatologist.