Hydrogen Peroxide (H2O2) drugstore variety, I take a small sip, brush and spit it out. Been doing it for almost 30yrs. My dentist always says my gums look great. Breaks down to oxygen and water. Simple, cheap and wonderfully supportive to healthy tissue. Oxidizes bacteria. U can pour it right into open wounds, add it to saline for ear and sinus flushing, gargle if u have a sore throat. Try not to swallow it tho. Magic stuff!