Prickly heat is a common superficial, inflammatory skin disease in summer or in hot environments. Due to the high temperature and sultry environment, a large amount of sweat does not evaporate easily, making the stratum corneum impregnated and swollen, narrowing or blocking the sweat ducts, leading to sweat retention, sweat extravasation of surrounding tissues, forming papules, blisters or pustules, mostly in the folds. The clinical manifestations of prickly heat vary 1. Crystal corn rash, also known as white prickly heat, is caused by sweat overflowing in the stratum corneum or the sweat ducts under the stratum corneum. It is common in patients with high fever and heavy sweating, prolonged bed rest, and excessive weakness. The lesions are small superficial blisters with thin, clear walls and no surrounding redness, which are easily broken by light rubbing and dry with fine scales. There are self-limiting, generally no conscious symptoms. 2, red corn rash, also known as red prickly heat, due to sweat in the spiny layer of sweat duct overflow caused. Acute onset, the lesions appear in batches as rounded and pointed pinhead-sized dense papules or papules, surrounded by a mild red halo. The lesions fade with mild flaking. A mild burning, tingling sensation is felt. 3. Pustular milia, also known as pustular prickly rash. Mostly developed from red corn rash. The lesions are dense papules topped with superficial pinhead-sized pustules. The pustules are often filled with sterile or non-pathogenic cocci. 4. Deep milia, also known as deep prickly rash, is caused by sweat overflowing in the upper dermis, especially at the dermal-epidermal junction. It is common in patients with severe and recurrent red milia. The lesions are dense, skin-colored blisters that are clear and do not easily break down, increasing in size when sweating and decreasing in size when not sweating. When the rash is widespread, sweating is reduced or absent throughout the body, and there may be compensatory increased sweating on the face, axillae, hands and feet, which may cause tropical sweating failure or heat exhaustion, and the patient may experience general symptoms such as weakness, sleepiness, dizziness and headache.