Red rashes in hot weather may be caused by prickly heat, eczema, mosquito bites and other factors. It is recommended to detach from the environment, external use of anti-itch glucocorticoid drugs, if necessary, with oral antihistamine treatment. 1. prickly heat: summer heat, sweat in the sweat ducts sweat stagnation, pressure increases, sweat duct rupture, sweat extravasation of the surrounding tissue and lead to localized red papules. It can be applied externally with glycerite lotion, which has the effect of astringency and itching, and can promote the recovery of the affected area. 2. Eczema: the causes of eczema are complex, considerations related to the environment, diet and other factors, resulting in skin rashes, the treatment of eczema drugs for glucocorticoid hormones, such as mometasone furoate ointment, hydrocortisone butyrate cream and so on. 3. Mosquito bites: often in and out of the external environment, mosquitoes bite the skin resulting in a red rash. It is recommended to get out of the environment, if the itching is serious, apply glycerine lotion, mometasone furoate cream, etc., if necessary, with oral loratadine, cetirizine and other antihistamines, can help relieve symptoms. Hot weather rash is related to a variety of factors, is a skin problem, it is recommended to go to the hospital dermatology department, under the guidance of the doctor for treatment.