Large red and swollen pimples on the back may be related to folliculitis, acne, boils and other factors, which can be treated with topical medication, oral medication and daily care. 1. Folliculitis: It is related to lack of attention to skin hygiene and bacterial infections, which can lead to large red and swollen pimples on the back. It can be treated with topical application of fusidic acid ointment, erythromycin ointment and other medications, which can play the role of anti-inflammatory and bactericidal. 2. Acne: related to the sebaceous gland secretion, can be applied locally Vitamin A cream, tazarotene gel and other medications, can improve the local redness and swelling symptoms. Pay attention to local hygiene and keep the local skin dry and clean. 3. Boils: usually caused by Staphylococcus aureus stimulating the hair follicles, resulting in purulent inflammation, can take anti-infective drugs, such as cefixime, doxycycline, etc., can promote the local redness and swelling of pimples subside. It is recommended that patients with red and swollen pimples on the back go to the hospital, to clarify the cause, and follow the doctor’s instructions for treatment, not blindly use drugs.