What chemical reaction is happening when hydrogen peroxide is bubbling away on an infected cut? How is it that H[sub]2[/sub]O[sub]2[/sub] more readily damages pathogens vs. healthy tissue?
I do not know what causes the bubbling, but it’s the excess oxygen (H2O2) that’s being released leaving behind water. As for killing anything, I’m not sure if it does that. My doctor told me that it is good for cleaning, but that I should use alcohol for infections.
The bubbling is caused by catalase, an enzyme that breaks down peroxides in blood. Peroxide does destroy healthy tissue, which is why we have catalase in the first place. It’s just that bacteria are more susceptible, being single-celled and all, so we don’t have to use a concentration which would cause burns on our skin.
I recently got a really sore throat and remembered hearing that pouring a little hydrogen peroxide in your ears would help and I did so and it went away in an hour or two, is it safe to use hydrogen peroxide in the ears? I’ve also heard of people using rubbing alcohol in the ears for water that is trapped in the ear, is that safe?
It’s safe to mix alcohol and vinegar 50/50 in the ears. Just had this done at family doc for clearing out water to narrow down the ear congestion issue I had from swimming or flying. (outer ear versus middle ear issue to be narrowed down)
Peroxide works like bleach ??? Is that fair to say?
Uhhh, more or less. Both are strong oxidizers. However, there’s a bit more to chlorine bleach than “electron hops from oxygen to whatever,” IIRC. Both will “bleach” things, however (incidental contact with 30% hydrogen peroxide turned my thumb white (and raised a blister) in just a few seconds).
Many bacteria, including species that are commonly found on human skin, make catalase. In fact, it’s a simple and useful test that’s used when identifying bacterial species - put some hydrogen peroxide on a colony of your unknown sample, and see if it bubbles or not.
An MD once told me not to use H202 on wounds so I did a quick search and found this:
It runs counter to what others say, but they don’t dispel the myth. I’d be curious to know about the bacteria thing. It makes sense that it might kill anaerobic bacteria, but if the H202 can get to it, I figure O2 could as well. I could see how a foaming reaction from appying it to dead material and no reaction to living material would make someone believe it killed bacteria. Perhaps it just oxidizes dead tissue, leaving
bacteria to stick around for the next round of cell death? Anyone?
Submitted too early–
What I was getting at was that H202 might be good at cleaning the wound of debris that bacteria feed on, but not bacteria itself. If you used H2O2 AND an antiseptic perhaps you could kill current bacteria and make the wound inhospitable to new infection.
Well, they’ve vastly overstated the issue. Hydrogen peroxide kills bacteria, period. The 3% solution used on wounds, however, isn’t that strong, and much of the peroxide is broken down on contact by our own enzymes. Therefore, there’s a high risk of bacteria remaining in the wound. The real benefit of peroxide is that the foaming action helps to clean out the wound. As I’ve already said, peroxide does harm human tissue, but not very much of it in the course of a typical first aid treatment. However, it’s certainly true that Betadine is more effective, and triple antibiotic ointment is the clear choice for continued care.
A chemist friend of mine once told me (and was later confirmed by my pharmacist) that buying peroxide wasn’t a good idea since the H2O2 breaks down too quickly and the solution becomes ineffective after a short period of time. I think the stable form of a hydrogen-oxygen compound is H2O (water) and so as H2O2, the compound does not stay in its H2O2 form for long periods of time. So your bottle of peroxide in your bathroom cupboard apparently becomes nothing more than glorified water after a little while (even if it still fizzes). It may even have reached that point in the drug store itself, depending on how long it’s been shelfed (?) at the pharmacy. Supposedly, that’s why peroxide comes in that dark opaque bottle (it’s supposed to slow this breakdown reaction), as opposed to say, rubbing alcohol, which comes in similar packaging but with regular translucent plastic.
Who knows, I may be out to lunch on this one. I just use Dettol, which is an antiseptic solution designed to also clean toilets (it says so on the bottle!) on top of bumps and bruises. It hurts less than rubbing alcohol and the stuff lasts forever.
To expand on the H2O2 controversy, I read that given what we now know about free radicals and cell damage, that H2O2 should not be used on wounds because it contributes to this.
does anyone have an answer to my earlier post? 
As a matter of fact, pool, I remember a doctor telling me once that it was OK to use isopropyl alchohol (a small amount) in the ear because it would evaporate quickly. But I’d reconfirm that before trying it, as that was many years ago.
Well talk to your doctor but mine said yes; she recommended it to help prevent earwax buildup (I’ll spare you the icky details of how much crud she pulled out of my ears but it was nasty). Since peroxide leaves water (which I don’t want sitting in my ears all day either) I take a two-pronged approach and use peroxide followed by rubbing alcohol to keep things clean and dry. I think that we had a thread on this a few weeks ago.