Folliculitis on the buttocks is usually caused by bacterial infection (often Staphylococcus), friction, sweating, tight clothing, or blocked hair follicles, which is why it commonly occurs in this area due to constant pressure when sitting, moisture buildup, and irritation from clothing or shaving. Mild cases often improve with antibacterial washes (like benzoyl peroxide), warm compresses, topical antibiotics (as prescribed), loose breathable clothing, and good hygiene practices to reduce sweat and friction. You should see a dermatologist if the condition is recurrent, painful, spreading, forms boils, or does not improve within 1–2 weeks, as stronger prescription treatment or evaluation for resistant infection may be needed.