Red rashes in summer may be related to mosquito bites, or may be caused by prickly heat, contact dermatitis, folliculitis and other causes. 1. Mosquito bites: in the hot summer, mosquitoes are more, if inadvertently bitten by mosquitoes, may lead to an inflammatory reaction of the bitten skin, there may be the phenomenon of red rashes, mainly in the form of scattered, isolated red rashes. 2. Prickly heat: in the hot summer, the human body sweats more, if the sweat is not discharged in a timely manner, long time accumulation in the skin, easy to cause skin inflammation, may form prickly heat, resulting in a red rash, but also with obvious itching symptoms. 3. Contact dermatitis: common in allergic people, in the summer after contact with pollen, strong ultraviolet light, is likely to cause an allergic reaction, induced contact dermatitis, may lead to red rashes on the body. 4. Folliculitis: often occurs in the chest and back as well as the trunk bit sebaceous gland rich parts. If the usual cleaning is not in place, it is easy to lead to a large number of sebum residue, resulting in local bacteria, fungi breeding, induced folliculitis, can also cause a red rash on the body. Red rashes in the summer, may also be caused by other reasons, if the symptoms are obvious, you should seek medical attention as soon as possible, to give targeted treatment.