Redness of the buttocks may be caused by trauma or contact dermatitis, ringworm, eczema and other diseases. 1. Trauma: If the buttocks are stimulated by trauma, it may lead to dilation and rupture of the capillaries under the skin of the affected area, resulting in epidermal redness, swelling, pain, ecchymosis and other symptoms. 2. Contact dermatitis: If the buttocks are exposed to allergens or stimulated by chemicals, it may induce an allergic reaction, causing the patient to experience symptoms such as buttock redness and itching. 3. Ringworm: ringworm belongs to a kind of fungal infectious disease, if the buttocks are infected with trichophyton, epidermolysis bullosa and other fungi, it may induce ringworm, which will make the patient’s buttocks appear red spots, pimples, flaking and other symptoms. 4. Eczema: If the buttocks are in a humid environment for a long time or the immune function is abnormal, it is easy to induce eczema, which leads to redness and blisters. There are many reasons for the redness of the buttocks, and it is recommended that patients go to the hospital to find the cause of the disease.