Limited evidence suggests that mouthrinses may be effective in reducing oral malodour

Medline, The Cochrane Central Register of Controlled Trials (CENTRAL) and Embase databases were searched.

Screening and selection of studies was conducted independently by two authors, with randomised controlled trials (RCTs) or controlled clinical trials (CCTs) conducted in adults 18 years or older being included. Studies used the outcome measures of volatile sulphur compounds (VSCs), organoleptic measurement (OM) and tongue coating (TC). Studies with a duration of greater than one day were included. Selection was restricted to English language papers.

Study quality was assessed by two authors with studies being separated into short- term (< 3 weeks) and longer-term study period groups (≥3 weeks). Meta-analysis was not conducted because of heterogeneity in the study designs, products used, outcome measures and data presentation.

Twelve RCTs were included (six cross-over studies and six parallel design). The short-term studies ranged from four days to two weeks and the long-term studies from three to four weeks. The risk of bias was assessed as high for two studies, moderate for three and low for seven. Nearly all mouthwashes with active ingredients had beneficial effects in reducing oral malodour in both short- and longer-term studies.

The most compelling evidence was provided for chlorhexidine mouthwashes, and those that contained a combination of cetyl pyridinum chloride and zinc provided the best evidence profile on oral malodour. Little data with respect to tongue coating were available, and none of the studies showed a beneficial effect for this parameter.