What is the cause of red lumps on the baby's back?

The most common red pimples on the baby's back are: 1. eczema. Normal manifestations are papules, erythema, and also show dandruff. If the rash is relatively large, there will be obvious itching. 2. The red pimples on the baby's back may also be prickly heat. Prickly heat occurs in hot weather. It is characterized by millet-like small papules, with slight redness around the rash, accompanied by itching. Third, the baby's back from red lumps considered urticaria, but also an allergic skin disease. The above health science knowledge is for reference only, the specific situation needs to be checked by a regular hospital, judged by a professional doctor.