Painful redness in the armpits in summer may be caused by diseases such as axillary sweatshirt, intertriginous rash, sebaceous cysts, etc., which are usually treated with medication and surgery. 1. Armpititis: Armpititis may be related to skin breakage, bacterial infection and other factors, manifesting as edematous papules in the armpits, accompanied by pain. The topical antibiotic ointment, such as mupirocin ointment, fusidic acid cream, etc., can be used topically, while oral antibiotic drugs, such as roxithromycin capsule, doxycycline tablets. 2. Interfluvial rash: Interfluvial rash is an acute skin inflammation caused by moisture and friction in the folded area of the skin, preferably in the armpits, groin, etc. It manifests itself as erythema, papules, blisters, vesicles, oozing, etc., accompanied by a burning pain. Local topical aluminum sulfate solution can be used for wet compresses, while local topical glucocorticoid ointment, such as hydrocortisone butyrate cream, mometasone furoate cream, etc.; if accompanied by local infections, topical antibiotic cream, such as erythromycin cream, ofloxacin ointment, etc.. 3. Sebaceous cysts: Sebaceous gland ducts in the armpits are blocked, leading to sebum retention and the formation of cystic swelling, secondary bacterial infection, can be manifested as red subcutaneous swelling in the armpits, accompanied by pain. At this time, anti-infection treatment is needed, such as topical mupirocin ointment, oral cefixime and other antibiotics. Surgery to remove the cyst after the inflammation subsides. All of the above drugs have adverse reactions and are recommended to be used under the guidance of a doctor. Summer armpit pain and redness, if the patient’s symptoms are serious, or the symptoms persist and do not improve, it is recommended to go to the hospital in time for treatment.