When we were kids, the infamous brown bottle was whipped out every time we scraped our knees, but this video from SciShow explains that hydrogen peroxide isn't the best way to heal a cut. The gross (and painful!) bubbling that happens after pouring hydrogen peroxide on a wound makes it seem like it's working, but it's actually the reason you shouldn't use it. Hydrogen peroxide is so good at killing bacteria that it also kills your healthy cells, which are there to help you heal. So the next time you get a cut (let's be honest, most of us are still pretty clumsy), soap and water should do the trick.