Small red bumps on the back in summer can be caused by prickly heat, folliculitis, contact dermatitis and other diseases. 1. prickly heat: in summer, long time in the hot environment, the back sweat more, may make the back prickly heat, will lead to small red bumps on the back, accompanied by itching or burning sensation. 2 folliculitis: more hair follicles on the back, increased sweating on the back in summer, do not pay attention to the back of the clean, easy to induce folliculitis, which will make small red bumps on the back, accompanied by redness, swelling, pain and other symptoms. 3. Contact dermatitis: contact with irritating or sensitizing substances leads to an allergic reaction on the back skin, which can cause small red bumps on the back, accompanied by intense itching. Small red bumps on the back in summer, and with obvious abnormal symptoms, it is recommended to consult a doctor for examination and treatment.