Most commonly, the chemical hydrogen peroxide (H2O2) is used in the home to disinfect superficial wounds such as cuts and scrapes and as a treatment for acne. The solution sold for this use is a very diluted version of the chemical, in which it comprises only 3 percent of the mixture, the rest is water. It should be used with caution, though, as hydrogen peroxide can cause unpleasant reactions like rashes and redness in those who are allergic to it, and overexposure can burn the skin of non-allergic people.
Hydrogen Peroxide in the Body
A scientific study that appeared in the journal Nature explained how the chemical hydrogen peroxide—found in trace levels in the bodies of all animals—plays in immune response. The study examined zebra fish: After the creatures sustained injuries, hydrogen peroxide levels in their cells increased. This signaled their bodies to send white blood cells to the wound site, thus speeding up healing. This same response is expected to occur in humans, as we are genetically similar to the fish studied.
How It Fights Infection
Many infections that affect the skin are caused by anaerobic bacteria, and oxygen inhibits its growth. When 3-percent-strength hydrogen peroxide is used to clean a wound, the body's natural enzyme catalase causes the bonds in the chemical to break, yielding oxygen and water. While the latter rinses out of the injury, the oxygen kills anaerobic bacteria. Hydrogen peroxide works in a similar way to help treat acne, which is caused by Propionibacterium acnes, an anaerobic bacterium.
Since hydrogen peroxide functions as an oxidizer, there is a potential for burns when it is applied to the skin. Many have observed whitening on the tips of fingers exposed to the chemical for a long period, this is because hydrogen peroxide is absorbed into the skin, where it can create a skin capillary embolism. Over-application or the use of a high-concentration form of the chemical can damage skin cells, leading to chemical burns and blistering.
Sometimes, products have higher concentrations of hydrogen peroxide. A good example of this is drug-store hair-dye kits. Most include a concentrated hydrogen-peroxide based oxidizer that has been known to cause reactions on the skin of allergic people. Skin may tingle and burn, and redness and blistering may occur.