There are many causes of red rashes on a child’s buttocks, commonly eczema, sweat rash and folliculitis, which can be treated with skin care and topical medications. 1. Eczema: Eczema patients with skin barrier damage, should pay attention to moisturizing, can be used in the shower when the skin is still wet with mild moisturizing products (such as petroleum jelly), avoid contact with irritants (such as chemical fiber clothing or irritating skincare products), topical ointment can be used in low-potency corticosteroid cream (such as 2.5% hydrocortisone). 2. Sweat rash: Skin care should minimize sweating and keep the skin dry. Topical corticosteroid ointment (e.g. 2.5% hydrocortisone or 0.1% triamcinolone) can be used to relieve itching. 3. Folliculitis: you can go to the hospital to check whether it is caused by fungus or bacteria, and anti-infection treatment for the pathogen. If it is bacteria, you can use liquid wet compresses (such as furacilin solution) or apply anti-bacterial ointment (such as mupirocin ointment). It is recommended to visit a dermatologist to clarify the cause and use medication under the doctor’s supervision.