The red rash on the buttocks is considered to be an allergic reaction, and may also be related to boils, ringworm and other factors, which need to be actively treated. 1. Allergic reaction: contact with allergic substances may lead to allergic reactions on the buttocks, resulting in red rashes, which can generally be treated with anti-allergic drugs, such as glycerine lotion, levocetirizine tablets and so on. 2. Boils: If infected with Staphylococcus aureus, it may lead to inflammation of the hair follicles and the tissues around the hair follicles, resulting in boils and rashes on the buttocks, which can be treated with medications such as ichthyosin ointment and mupirocin ointment. 3. ringworm: patients with fungal infections may induce ringworm, can use ketoconazole cream, terbinafine cream and other drugs treatment. Usually need to pay attention to hygiene, more clean, change underwear, the above symptoms are recommended in the hospital dermatology consultation, the above drugs need to be used under the guidance of a doctor.