Many red bumps on the body may be caused by acne, folliculitis, contact dermatitis and other diseases. 1. Acne: the cause may be related to hormone level changes, excessive sebum secretion and other factors, the patient will appear pimples, pimples and other symptoms, can be seen on the chest, back, shoulders and so on. 2. Folliculitis: the cause is mainly related to Staphylococcus aureus, Malassezia and other pathogenic bacteria infection. Red papules appear locally and can be seen on any part of the body where there is hair. 3. Contact dermatitis: mainly due to allergic reaction or irritation caused by skin contact with exogenous substances. Patients will appear erythema, edema, papules and other symptoms. There are more reasons for a lot of red bumps on the body, and it is recommended to go to a regular hospital for examination to clarify the cause.