Charcoal-based mouthwashes: a literature review John K. Brooks,* 1 Nasir Bashirelahi, 2 Ru-ching Hsia 3 and Mark A. Reynolds 4 Introduction Mouthwashes are classifed by their chemical and antimicrobial properties and are designated as either cosmetic or therapeutic. Cosmetic types are recognised for ofering only temporary relief of halitosis. 1 Te American Dental Association (ADA) Science Institute has validated the efcacy and documented the range of active ingredients to be included in therapeutic mouthwashes, such as cetylpyridinium chloride, chlorhexidine, essential oils (eucalyptol, menthol, methyl salicylate, thymol), and fuoride. 2 With our increasingly health-conscious society, there has become a renewed interest in the potential merits of charcoal-containing products for personal hygiene, including skin and dental care. Te most common oral product containing charcoal is toothpaste, reviewed by Brooks et al., 3 and less frequently found in mouthwash, manual and electric toothbrush bristles, dental floss and floss picks, tooth whitening strips, and chewing gum. As such, consumers may be faced with the challenge of making decisions whether to use charcoal mouthwashes based upon the advertised claims of product efectiveness and safety. Tere is a paucity of clinical information concerning the effectiveness of over-the- counter charcoal mouthwash as an aid to oral hygiene (Fig. 1). The objective of this investigation was to substantiate whether there was clinical and laboratory evidence that the use of charcoal mouthwashes reduces gingival inflammation and promotes tooth whitening, as well as establishing any adverse efects. In this systematic review, we searched the literature for controlled clinical trials with a minimum follow-up of six months, evaluating the efect of charcoal-containing mouthwashes on therapeutic and cosmetic outcomes. In addition, we examined the product labels and information of commercially marketed charcoal-containing mouthwashes for recognised active ingredients. Methods Search strategy We established comprehensive search strategies for identifcation of studies for inclusion in this review. We searched MEDLINE and Scopus databases for reports on the efcacy and safety of charcoal-containing oral rinses published in the English language literature through 15 June 2019, using the following four strategies and search terms: 1. charcoal OR charcoal-based OR activated charcoal OR soot; 2. rinse; OR oral rinse OR mouthwash OR antiseptic; 3. oral hygiene OR oral health OR teeth OR dental; and 4. 1, 2, and 3. We also screened reference lists of potential articles for relevant published studies. Inclusion criteria of relevant studies Te inclusion strategy consisted of identifcation of randomised controlled clinical studies coincident with a follow-up assessment of at least six months, cohort studies, case reports and case series. Describes the emerging usage of charcoal-based oral hygiene products, preferentially regarding charcoal mouthwashes. Corroborates the lack of clinical and laboratory evidence that use of charcoal mouthwash provides therapeutic or cosmetic improvement. Deliberates whether the use of charcoal mouthwash may result in adverse oral outcomes, particularly being injurious to tooth structure. Key points Abstract The commercial marketplace has seen a rapid increase in the number of over-the-counter charcoal-containing mouthwashes. The purpose of this systemic review was to examine the clinical and laboratory evidence supporting therapeutic claims of ef fcacy and safety of use of charcoal-based mouthwashes. Secondly, the product labels and information of 36 commercially marketed charcoal mouthwashes were reviewed for active ingredients. Only 8% of charcoal mouthwashes contained an active ingredient, such as cetylpyridinium chloride or chlorhexidine. There is insuf fcient evidence to substantiate the therapeutic and cosmetic marketing claims of charcoal-based mouthwashes, 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 abrasivity of any of these products. Dental clinicians 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. 1 Clinical Professor, Department of Oncology and Diagnostic Sciences, University of Maryland School of Dentistry, Baltimore, Maryland; 2 Professor, Department of Oncology and Diagnostic Sciences, University of Maryland School of Dentistry, Baltimore, Maryland; 3 Associate Professor and Director, Electron Microscopy Core Imaging Facility, University of Maryland School of Medicine, Baltimore, Maryland; 4 Professor, Department of Advanced Oral Sciences and Therapeutics, University of Maryland School of Dentistry, Baltimore, Maryland. *Correspondence to: John K. Brooks Email: jbrooks@umaryland.edu Refereed Paper. Accepted 9 January 2020 https://doi.org/10.1038/s41415-020-1265-8 290 BRITISH DENTAL JOURNAL | VOLUME 228 NO. 4 | FEBRUARY 28 2020 GENERAL VERIFIABLE CPD PAPER © The Author(s), under exclusive licence to British Dental Association 2020