What is effect of peroxide mouth rinse used daily?

No problem: While it won't cure dental decay, it might improve the gum health. Just be sure you rinse and spit. It is not a substitute for treatment of gum disease or seeing your dentist. Make sure you go at least twice a year.

Peroxide?: Are you referring to using peroxide straight as mouth wash or a peroxide based mouth wash? Peroxide diluted in over the counter mouth was is safe and has no adverse side effect.

Fungal overgrowth: You don't want to use hydrogen peroxide as a rinse on a daily basis. If you do you will eliminate the good bacteria in your mouth. A common side effect is for a black fungus infection of your tongue.

It helps PC: Not political correctness but plaque control. We can not prevent the bacteria from living in our mouths, in fact we need them there to stop worse critters from living in there. But we must brush and floss and them rinse daily (nightly). The peroxide rinse helps with this program. Ask your dentist for advice please.