Abstract: A mouthwash solution to prevent enrichment, in the oral cavity on mucous membranes and dental surfaces, of metals, particularly heavy metals. The mouthwash solution contains water-soluble alkali metal or alkali earth metal salt or salts, particularly the Na, K, Mg or Ca salt, or their complex salt of an amino(carboxylic) acid forming with heavy metal ions stable, water-soluble complex compounds in oral cavity conditions.