Hydrogen Peroxide Peroxide is a mild antiseptic used on the skin to prevent infection of minor cuts, scrapes, and burns. It may also be used as a mouth rinse to help remove mucus or to relieve minor mouth irritation (e.g., due to canker/cold sores, gingivitis). Hydrogen Peroxide works by releasing oxygen when it is applied to the affected area. The release of oxygen causes foaming, which helps to remove dead skin and clean the area. Hydrogen Peroxide should not be used to treat deep wounds, animal bites, or serious burns.