Small red bumps on the skin may be related to contact dermatitis, eczema, prickly heat and so on. 1. Contact dermatitis: when the skin is in direct contact with some exogenous stimulants or allergic substances, it can cause an allergic reaction in the skin, which can be manifested as a small red pimple on the skin, which is a clear erythema, papule and small blister. 2. Eczema: a variety of internal and external factors lead to the occurrence of eczema, often manifested as erythema on the basis of the needle tip to grain size papules, papules, can be accompanied by itching symptoms, often due to scratching the formation of punctate vesicles, there is a clear plasma oozing. 3. Prickly heat: In summer or hot environment, if prickly heat appears on the body, it manifests itself as a dense arrangement of pinpoint-sized papules, papules, surrounded by a red halo, with mild flaking after the lesions subside. It is accompanied by burning and itching sensation. It is recommended that people with a small red bump on the skin go to a regular hospital in time to clarify the cause of the disease and standardize the treatment under the guidance of the doctor, so as not to bring adverse effects to the body due to delayed conditions.