A lot of red bumps on the back in the heat of the day may be due to heat rash, eczema, mosquito bites, etc., which can be treated by thorough cleaning, applying ointment, oral medication, and so on. 1. Heat rash: hot back pimples may be accompanied by redness, swelling, itching, do not scratch to cause infection, it is recommended to use warm water to wash the back, when serious, you can choose glycerine lotion to relieve itching, redness and swelling symptoms. 2. Eczema: local application of glucocorticoid creams such as dexamethasone and other anti-allergic, can also be combined with oral antihistamine drugs such as loratadine. 3. Mosquito bites: glucocorticoid creams such as mometasone furoate cream and hydrocortisone butyrate cream can be used externally, and oral antihistamines such as cetirizine can be combined if necessary. In addition, you need to ensure that the surrounding environment hygiene, if necessary, insecticide treatment. There may be other reasons for the red bumps on the back of the hot weather, it is recommended to go to the hospital in time to find out the cause, symptomatic treatment, the above drugs need to be used in accordance with the doctor’s instructions.