A lot of rashes on the back in summer may be caused by insect bite dermatitis, urticaria, prickly heat and so on, which can be treated by taking oral medication or applying medication. 1. Insect bite dermatitis: mosquitoes are more common in summer, and mosquito bites can lead to inflammatory reactions in the skin, such as petechiae and pimples, resulting in a lot of rashes on the back in summer. You can follow the doctor’s instructions to apply glycerine lotion, hydrocortisone butyrate cream and other medications. 2. Urticaria: is a relatively common skin disease, after the disease can lead to local skin and mucous membrane blood vessel dilation or increased permeability, resulting in the appearance of red bumps on the skin, leading to the phenomenon of the patient appeared in the summer on the back of a lot of rashes. You can follow the doctor’s instructions to take oral levocetirizine hydrochloride tablets, loratadine tablets and other drugs to treat. 3. prickly heat: also known as corn rash, summer is hot, sweat is not easy to evaporate will stay in the sweat ducts, resulting in sweat ducts dilation or even rupture, sweat leakage will stimulate the skin, thus appearing in the summer on the back of the phenomenon of a lot of rashes. You can follow the doctor’s instructions to use glycerin lotion, prickly heat powder and other drugs. At the same time, keep the skin fresh and dry. Summer back a lot of rashes can not be ruled out is caused by eczema and other reasons, the patient needs to consult a doctor for timely treatment, the application of medication needs to be under the guidance of the doctor strictly according to time, according to the dosage of the application.