That brown bottle under the bathroom sink has probably been there for years. Many of us grew up watching a parent pour it on a scraped knee and seeing it fizz. Hydrogen peroxide does have some genuinely useful jobs around the house, but one of its most famous uses is now one that doctors tell you to skip.
Key Takeaways
- The 3% hydrogen peroxide sold in drugstores is the only strength meant for home use. Stronger “food grade” (35%) versions can cause serious burns and should never be swallowed or used on the body.
- For cuts and scrapes, plain running water is better. Doctors no longer recommend peroxide for wound cleaning because it can irritate tissue and slow healing.
- For earwax, a few drops can help soften buildup, but skip it if you have a perforated eardrum, ear tubes or signs of an ear infection.
- For teeth whitening, it can lift surface stains, but overuse can cause tooth sensitivity and gum irritation. Check with your dentist first.
- For hair, diluted peroxide can gradually lighten color, but it’s drying, so use it sparingly.
First, know your bottle
Drugstore hydrogen peroxide is a 3% solution, meaning it’s mostly water. At that strength, splashes on the skin usually cause only mild irritation. Hair bleach products typically contain 6% to 10%. So-called “food-grade” hydrogen peroxide is about 35%. Despite the name, it is not food. Poison control experts warn that swallowing it can cause severe internal burns, and in rare cases dangerous gas bubbles in the bloodstream. People have been seriously injured or killed after drinking it as an “alternative therapy.” The FDA has warned against drinking high-strength hydrogen peroxide for medicinal purposes.
Light breaks hydrogen peroxide down into plain water and oxygen, which is why it comes in a dark bottle. If it no longer fizzes when it touches a cut or a sink drain, it has likely lost its strength.
1. Cuts and scrapes: put the bottle down
That satisfying fizz isn’t the germ-killing power many of us assumed. It happens when hydrogen peroxide reacts with an enzyme called catalase, which is found in blood and body tissues. The trouble is that peroxide doesn’t distinguish between bacteria and your own healing cells. Research has shown it can damage fibroblasts, the cells that rebuild skin and connective tissue, and higher concentrations can delay healing.
Mayo Clinic and Cleveland Clinic both advise against using hydrogen peroxide or iodine on cuts. Instead:
- Wash your hands, then press a clean cloth on the wound to stop the bleeding.
- Rinse the wound under clean running water, and wash the skin around it with soap.
- Remove any dirt with clean tweezers.
- Apply a thin layer of antibiotic ointment or petroleum jelly and cover it with a bandage.
See a doctor if the wound is deep or won’t stop bleeding, you can’t get all the dirt out, or you see signs of infection such as spreading redness, warmth, swelling, drainage or wors