Dr Mercola says that several drops in the ear at the first sign of a cold or flu can stave off the illness, he swears by it. I don't really think a few drops is going to have the potential to hurt me as long as I am not applying it to a compromised eardrum. i.e. my hubby has had ear surgery and his eardrum is a rebuilt one, and sometimes experiences irritation and bleeding... so no hydrogen peroxide treatment for him.
I have tried it but not often enough to be able to say how well I think it works. I also do other things that help me stay healthy so it's hard to say what it was that tipped the scale when success comes... the years I was in very regular chiro care with no other changes to my lifestyle, I didn't get the flu, when every single year before I always have gotten it.
Anyway I think it's worth a try. I don't know anything about the reasons behind the warning label other than it sounds much like the warning labels on most everything now, because of the fear of lawsuits...