Rashes on the body are usually erythema, red papules, etc. They may be caused by mosquito bites, or skin allergies or viral infections. 1. Mosquito bites: red skin spots, papules and pimples that appear after mosquito bites are usually accompanied by itchy skin symptoms. 2. Skin allergy phenomenon: such as eczema and other skin problems, easy to lead to chronic inflammatory changes in the skin, appearing on the body skin erythema, papules, scales, mossy changes, accompanied by intense itching and other symptoms. 3. Viral infections: part of the red rash is caused by viral infections, such as early childhood emergency rash, rubella, etc., the skin can also show red spots. If you find a red rash on your skin, if the rash does not disappear for many days in a row, or if the area of the rash expands in a short period of time, you need to go to the dermatology department of the hospital to diagnose the cause of the skin rash, and then treat the symptoms under the guidance of the doctor.