When poured onto a cut or scrape, hydrogen peroxide encounters blood and damaged skin cells. These contain an enzyme called catalase, which breaks down the hydrogen peroxide into water and oxygen. The fizzing you see in the form of bubbles is the oxygen gas escaping.

Does peroxide bubbles mean infection?

While not necessarily a “mistake”, a common misconception is that if hydrogen peroxide bubbles, it means your wound is infected. Hydrogen peroxide will bubble whether your wound is infected or not. A chemical reaction occurs while cleaning and creates little oxygen bubbles. Don't sweat over the bubbles.

What does hydrogen peroxide do?

Hydrogen 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).