Probiotics for the management of oral halitosis


A 2017 review (Dental Elf – 28th Aug 2017) estimated the prevalence of halitosis is to be 31.8% (95%CI; 24.6–39.0%). Volatile sulphur compounds (VSCs) produced as a result of microbial metabolism of proteinaceous substrates in the mouth lead to halitosis with the tongue also being implicated. A small number of cases are linked to periodontitis.  Probiotics because of their competitive exclusion of bacteria, immune modulation, and production of antimicrobial substances are thought to be a potential means of managing halitosis and several studies have been conducted.

The aim of this review was to evaluate the efficacy of probiotics in reducing halitosis of dental origin, when compared to a placebo intervention.


A protocol was registered on PROSPERO and the review conducted in line with the Preferred Reporting Items for Systematic review (PRISMA) guidelines. Searches were conducted in the Medline/PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL) and OpenGrey ( databases. Two reviewers independently screened and selected studies before extracting data with risk of bias being assessed using the Cochrane risk-of-bias tool 2.0 (RoB2). The primary outcome measures were organoleptic (OLT) scores and/or volatile sulphur concentration (VSC) levels with microbiologic parameters and quality of life (QoL) scores as secondary outcomes. A narrative summary was presented owing to study heterogeneity.


  • 8 RCTs (7 parallel, 1 cross-over) involving a total of 326 patients were included.
  • Follow -up periods ranged from 7 days to 3 months.
  • 2 studies were at high risk of bias, one at low risk and 5 had some concerns.
  • 3 studies used periodontally healthy patients, 2 included patients with mild chronic periodontitis, 2 involved patients with severe or stage III or IV periodontitis and 1 study used patients with treated periodontal disease.
  • 5 studies used a single species of probiotic and 2 a combination of species.
  • 4 studies used Lactobacillus salivarius and 3 studies used Lactobacillus reuteri
  • 4 studies administered probiotics as lozenges with tables, gum or mouth rinse being used in single studies with 1 study using a combination of mouth rinse and subgingival application.
  • Treatment duration and dosages varied between studies.
  • Some interventions demonstrated improvements on OLT, VSC, microbiological parameters and QoL with some showing no difference.


The authors concluded: –

The available evidence is not suggestive of a convincing benefit for the use of probiotics for treatment outcomes of halitosis. Although an effective probiotic regimen cannot be identified at this point, further research should standardise how OLT scores are measured, and how breath samples are obtained. Finally, it appears premature to provide definitive clinical recommendations based on the limited number of low-quality studies.


The authors have adopted a good methodological approach preregistering a protocol with PROSPERO and following the PRISMA guidelines. A good range of databases were searched with 8 RCTs being included. However, the included studies were small and patient recruitment was variable as were the assessment criteria for halitosis. There was also variation in the in the treatment regimes, treatment duration and follow up periods. Consequently, the available evidence is both limited in quantity and quality.

A recent Cochrane review (Dental Elf – 13th Jan 2020) looked more broadly at interventions to prevent and control halitosis concluding: –

We found low- to very low-certainty evidence to support the effectiveness of interventions for managing halitosis compared to placebo or control for the OLT and patient-reported outcomes tested. We were unable to draw any conclusions regarding the superiority of any intervention or concentration. Well-planned RCTs need to be conducted by standardising the interventions and concentrations.

The Cochrane reviewers included 44 RCTs which they classified into several areas, mechanical debridement, chewing gums, systemic deodorising agents, topical agents, toothpastes, mouthrinse/mouthwash, tablets, and combination methods.  Six of the studies included in this current review of probiotics were published prior to the 2020 Cochrane review with just two of the studies being included in both reviews. Both these reviews point to the need for high quality studies in halitosis research following recognised best practice and using common outcome sets.


Primary Paper

Tay JRH, Ng E, Lai CWM, Lim LP, Ong MMA. The efficacy of probiotics in the management of intra-oral halitosis: a systematic review. Clin Oral Investig. 2022 Jul;26(7):4687-4700. doi: 10.1007/s00784-022-04522-w. Epub 2022 May 10. PMID: 35536439.

Review protocol on PROSPERO

Other references

Dental Elf – 28th Aug 2017

Bad breath: how common is it?

Dental Elf – 13th Jan 2020

Halitosis: What are the best methods of prevention and control?

Dental Elf – 23rd Jan 2023

Chlorine dioxide mouthwash for halitosis



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