Itchy itch when it is hot may be related to cholinergic urticaria, atopic dermatitis and other diseases. 1. Cholinergic urticaria: its cause may be related to the local center of the skin temperature rise, such as sports, alcohol, stress, hot baths, hot weather and other factors. Its main manifestation is the appearance of fine, itchy, stinging wind clouds in the skin lesions. 2. Atopic dermatitis: its etiology may be related to factors such as genetics, immune abnormalities, abnormal skin barrier function, etc. Seasonal and temperature changes may also induce the disease. Patients will experience dry skin, intense itching and other symptoms, and some patients may experience itching all over the body after being exposed to heat. There is no single cause of itching when exposed to heat, and patients are advised to seek medical examination to clarify the cause of the disease.