The back of the hot pack is particularly itchy, may be a normal physiological reaction, can also be considered with vasodilatation, contact dermatitis and other factors caused. It is recommended to pay attention to supplemental water, if necessary, give antihistamine, glucocorticoid drugs to regulate. 1. Normal phenomenon: hot compresses when the skin itchy, consider and hot compresses when the skin water evaporation, skin dryness, dehydration. It is recommended to pay attention to water supplementation or local application of moisturizing cream after hot compresses can help alleviate the symptoms. 2. Vasodilatation: hot compresses may lead to subcutaneous capillary dilatation, there may be a slight itchy situation. Itchy symptoms are relatively mild, generally do not need special treatment. 3. Contact dermatitis: everyone has a different skin type, if the skin type is sensitive or allergic reaction, there may be itchy skin, erythema, pimples and other manifestations. You can use topical glycerite lotion, together with oral loratadine, levocetirizine hydrochloride and other drugs, can help relieve the symptoms. Itchy skin when applying hot compresses, the symptoms can be gradually relieved after applying hot compresses, generally do not need special treatment. If the itchy symptoms persist or red spots appear, it is recommended to go to the dermatology department of the hospital to find out the cause. The above medications should be used in accordance with medical advice.