I put the peroxide in a squeeze bottle (for ex, an old M9 bottle) and just squeeze a little in the bag after I've emptied. I haven't had any problem w/it on my stoma -- people use hydrogen peroxide as a gargle and for canker sores, and the cheek tissue is the same type as the stoma tissue.
It doesn't work perfectly, especially if I eat something like fish, but it takes away most of the smell.
I don't really stick my nose in the bag to check how much it smells
, but I think that mostly it keeps the bag from smelling.
I will say that when I've mentioned the hydrogen peroxide to stoma nurses, they get concerned.... but it's from being unfamiliar not from knowing of any specific dangers. I've seen it recommended in a variety of places, and it felt safe enough to me to give it a try, and I've had no problems.
BTW it's also used at waste treatment plants for sewage, same basic idea.....
I also like that it's clear. I managed to spill M9 in the bathroom several times in the middle of the night, and that's messy....