Doxycycline for Boils, Folliculitis, Carbuncles. Doxycycline is FDA-approved for the treatment of S. aureus skin infections. Staphylococcus aureus (commonly called staph) is the primary cause of folliculitis, furuncles (abscessed hair follicles or “boils”), carbuncles (cluster of furuncles), and skin abscesses. S. aureus is the leading cause of skin and soft tissue infections worldwide.