Wasn't aware of this, here's what I find on a search:

The problem with hydrogen peroxide, it may be killing the germs, but it's also killing the healthy tissue in there too ... and that can then cause a larger wound than we would have had otherwise. And quite honestly, that whole process of sterilizing it and killing everything off isn't really necessary. You don't need that. You don't need to make this a completely sterile environment. The body is set up to fight off bacteria and help to heal things, so you're probably doing more harm than good with it.

Simple tap water. It's very simple. If you can just run that wound under tap water for like 5 minutes, 5 to 10 minutes, lukewarm water, just let that water run through it, clean it out, just kind of wash it out. You don't have to spray it on there. It doesn't have to be high pressure. ... Studies have been done looking at that and have shown that works just great, just as well as anything else in terms of getting that wound cleaned out and avoiding infection.

https://healthcare.utah.edu/the-scope/health-library/all/2023/04/should-you-use-hydrogen-peroxide-clean-wound

I've never used it for wound care. I keep it in the first aid kit because of its use in cleaning up biohazards.

Eh, in general, the use case for peroxide instead of anything else on wounds just isn't there.

Anything that's meant to kill off small living cells is going to do exactly that, and not give a damn if those cells are bacteria or your body. Now, it is true that not all chemicals will kill off every given microbe equally, and that applies to your skin/muscle cells as well. That still doesn't mean that any given agent is going to do anything useful for your healing.

If the concern is microbes, germs, quantity of rinsing simply does a better job at cleaning a wound of them. A lot of water is better than a minimal use of peroxide or alcohol, or whatever. For one thing, if you have running water, you don't have to keep opening new bottles. If you're out in the woods, you can still have a better chance of a large amount of water being available compared to finding a magic spring that spouts peroxide. So just the reality of availability makes carrying that kind of thing kinda pointless.

It's easy to look at all the bubbling peroxide does and think it's really getting in there and pulling things out, but it isn't true. If anything, the bubbling is reducing contact time with anything it's supposed to be killing. So you'd have to continue rinsing with it. And then you're right back to where water alone is better.

You don't need soap for wounds either. Indeed, you shouldn't be using it in wounds in the first place. That's never been a recommendation that I've seen. Not surprising that it would irritate a wound bed. You can use soap on the skin around a wound, but even that isn't necessary, and it's not useful unless there's contamination from something that water alone won't clear away. The only time I can think of where soap would be used directly in the boundaries of a wound would be with some kind of thick, oily substance being in it. Even then, I'm dubious as to how much benefit you'd get compared to just water or saline with gentle wiping of the wound.

Peroxide also isn't going to do anything positive to reduce bleeding. The opposite, actually, since it's going to break up platelets trying to form a scab. You might wash away enough blood from a minor cut that it takes longer to be visibly bloody again, but that just means it wasn't bleeding fast to begin with.

And, once you've used peroxide, you still have to rinse because if you don't, not only are all the particulates still in the wound, so is the peroxide. So you'd have the stuff sitting there killing cells well after you bandage the wound, and that's not a good thing at all. So why waste money and time when you can just rinse instead?

Even if you have a contaminated water supply, you'd still be better off buying saline in bottles for wound cleaning than peroxide.

You may or may not notice a difference in healing if you had identical wounds at the same time and used different methods to clean them. That's not the kind of experiment you can get away with clinically. But, if you compare outcomes from enough people over time, it starts showing up that wounds heal at least a tiny bit slower, and often less evenly. I've never read anything about scar formation, but I suspect that if you did it with two wound on the same person, you'd end up with a measurable (if miniscule) difference there.

I'm not saying to never ever use it. It's better than nothing at flushing a wound out. If you aren't in a situation where anything else is possible, go for it. But I wouldn't reach for it first.

i water my house plants with it if fungus gnats start swarming around

The reason stuff gets inflamed and sensitive with soap and water is because it's healing the damage, rather than just destroying everything in the damaged area and hoping it grows back right. Your body will generally do fine if you're young and healthy, but as you get older it becomes more of a risk.

It's not guaranteed to do more harm than good, but because it destroys healthy cells too it creates a risk that just doesn't need to be taken. It's not more effective at preventing infection than soap and water, and it's not as effective as medical super glue for stopping bleeding, so there just isn't a place for it any more.

Before knowing about this new information I had the feeling that a badly torn and stitched together sheep's udder with a really big hole started healing a lot faster when I stopped doing (in this order) Peroxide - Betadine - Omnimatrix - Charcoal and just went with Betadine - Omnimatrix - Charcoal. It's very anecdotal data from one sheep, but I find it interesting to be confirmed by some science.

Also there's the issue of h2o2 introducing oxygen to the wound. So while yes, some bacteria may be killed, you are encouraging others to grow. "Bacteria" isn't a single thing. It's a whole ecosystem. It's like, ok great you killed all the wolves. Now we have bears.

This isn’t recent. This has been an ongoing thing for at least 20 years (if not longer; that’s just the earliest I remember having this convo). Yes, it cleans the wound by killing things but it also fucks up the healthy tissue around the wound (see other comments for a more scientific explanation). Having some in a medical kit is useful for other activities such as diluting with water for an ear rinse, diluting with water for various mouth stuff (rinse not swallow), and some skin treatments (again, diluting first).

Maybe this should go in no stupid questions, but I'm curious to hear the explanation too. Am I just outdated? I thought every good home first aid kit should have a bottle.

Not sure if this is true but someone once told me that using hydrogen peroxide on wounds of a certain size might lead to a bubble of gas appearing in the bloodstream, which would be undesirable. I dunno, I rinse my mouth with diluted h2o2 occasionally and might put it on a small scrape but I'm a little leery after hearing that. Also the "cauterizing" effect seems like it might slow healing or cause a more notable scar.

If you really want to know, I’m sure there are medical journal articles and scientific research papers on why the “hate.”