Experience the fresh taste of clean! Hydrogen Peroxide Mouthwash Hydrogen peroxide is equivalent to chlorine dioxide-based mouthwashes in its ability to convert sulfides (the germs which cause halitosis) into sulfates. You can feel the oxygen-releasing molecules make your mouth come alive. We combined the powerful oils of eucalyptus, menthol and thyme, with filtered water and hydrogen peroxide, to bring you an effective, good-tasting mouthwash.