In February 2020 researchers from the USA published their review of the evidence concerning claims currently being made on the effectiveness and safety of charcoal-based mouthwashes. The product labels and information on 36 commercially marketed charcoal mouthwashes were reviewed for active ingredients. Results showed that only 8% of charcoal mouthwashes contained an active ingredient, such as cetylpyridinium chloride or chlorhexidine. Overall, there is insufficient evidence to substantiate the therapeutic and cosmetic marketing claims currently being made, including antimicrobial activity, anti-halitosis, tooth whitening, periodontal disease control, caries reduction and tooth remineralisation, among others. Moreover, there is no available information on charcoal particulate size or how abrasive the products are. The researchers therefore concluded that dentists should advise their patients to exercise caution when using over-the-counter charcoal-containing mouthwashes because of the lack of evidence supporting therapeutic or cosmetic effectiveness as well as safety.
Brooks JK et al. Charcoal-based mouthwashes: a literature review. Br Dent J. 2020 Feb;228(4):290-294