Rash refers to a skin rash, which is a skin condition, while prickly heat is a disease, and there is a fundamental difference between the two. 1. Rash: Rash is a manifestation of skin damage, which can be caused by a variety of diseases such as eczema, herpes zoster, and anaphylactic purpura. Some patients have rashes also related to the application of sulfonamide drugs, excessive sun exposure, environmental pollution, daily not pay attention to personal hygiene and other factors. Usually the patient’s skin color, shape will change, can be accompanied by itching, tenderness and other symptoms. 2. Prickly heat: Prickly heat is a skin disease that occurs in summer or under hot and humid environment. Prickly heat often causes small blisters, papules or dermatomes on the localized skin, and may be accompanied by tingling, itching and other uncomfortable symptoms. A general dermoscopy can help assist in the diagnosis of prickly heat. When localized skin abnormalities occur, patients should seek timely medical treatment to avoid aggravation of the condition. Daily attention should be paid to skin care, avoiding friction and irritation by foreign objects or contact with allergenic substances.