What do you suggest if my friend, and i need to know how to help her! is it safe to swab mercurochrome or hydrogen peroxide onto her mouth to disinfect it?

Mercurochrome/ H2O2: Although merbromin (organic mercury) in mercurochrome is reported to be benign – you wouldn't catch me putting mercury in my mouth. Sometimes low concentrations of Hydrogen Peroxide (H2O2) are used in the mouth. But if she has oral lesions, the H2O2 can actually cause tissue damage and is not considered to be a good antiseptic. Has she tried gargling with warm salt water?