Scrapes, cuts, nicks, gauges, blisters. They all got the same treatment. Hobble into the kitchen, grab the opaque brown bottle from the medicine cupboard, twist off the lid, and douse the wound with a couple quick glugs of hydrogen peroxide. The sting as it touches broken skin is quick and sharp and strangely satisfying, the hissing white froth a sure sign the stuff is working-- or so I was always told. Antiseptics sting, after all, and hydrogen peroxide certainly stings (albeit lightly-- one of its many charms). Surely it was doing its job, giving unwelcome bacteria the heave-ho.
Except it wasn't. Rather, it was inflaming my already damaged cells, prolonging the healing process and contributing to the development of scars. I've got one on my elbow that might be smaller-- might, in fact, not be there at all-- if I hadn't been such a devout peroxide disciple.
But if peroxide really isn't a useful disinfectant, then why do we use it? Why do we even have it kicking around our medicine cabinets at all?
Because we think it works, and often that is reason enough. Conventional wisdom bears incredible weight. Once it settles into its groove, it can be nearly impossible to budge. And peroxide makes a good show of working, certainly. The sizzle, the sting, the bubbly froth, it all contributes to an appealing but largely erroneous appearance of an antiseptic in action.
And we like that.
As for my second question, peroxide has a number of great household uses, in addition to its industrial applications as a rocket propellant, sulfide oxidizer, and wastewater pretreatment agent. It bleaches hair, oxygenates fish tanks, cleans stubborn tile grout, and can make an effective (if unpleasant-tasting) toothpaste.
Strangely, it's even a pretty good disinfectant.
This may sound flatly contradictory, but hydrogen peroxide has strong antiseptic properties-- just not when it's on your skin. Applied in full strength to inanimate objects, it does a great job. It even functions as an important part of your immune system.
The problem is not that peroxide doesn't kill bacteria, but that its not discriminating enough to avoid damaging your skin in the process. To keep it in check for topical purposes, we dilute it to 3% strength, at which point it loses the punch necessary to control invasive bacteria.
The unexpected truth about hydrogen peroxide tells a larger story about our unwillingness to let go of fraudulent information if that information was passed to us from a trusted source, especially if it came at a young age. Heck, I wrote a post last week about my reluctance to accept that the moon has no bearing on human behaviour despite a recent study stating otherwise (though when it comes to scientifically verified evidence, the claim that peroxide doesn't disinfect cuts is on much sturdier ground).
Sometimes it hurts to let go. But an infection hurts worse.
And at least I still have Polysporin.