Abstract Background Plaque-induced gingivitis is a chronic inflammatory condition characterized by complete reversibility of tissue damage once the periodontal biofilm has been disorganised. The aim of this study was to evaluate the efficacy of two commercially available mouthwashes (MWs) versus a chlorhexidine (CHX) 0.12% MW in reducing gingival bleeding (GB) in adults with plaque-induced gingivitis. Methods The present study was a double-blind, parallel, randomized controlled trial involving 6492 gingival sites (i.e. 39 subjects × 28 teeth × 6 sites/tooth) aged 18–75 years. During a 2-week period, subjects were randomized to receive MWs: a control CHX 0.12% MW (group C, 1818 sites); a MW test containing CHX 0.09% + Citrox®/P complex (group CX, 2628 sites); a MW test based on natural compounds (group P, 2016 sites). GB was assessed at the inclusion visit (T 0 ) and after 2 weeks of MW use (T 1 ). Analyses of GB were compared between groups and then restricted to subjects with bleeding sites between 10 and 30% (moderate gingivitis) or ≥ 30% (severe gingivitis) at T 0 . Pairwise comparisons were made between groups and logistic regression was used to identify correlates of GB (T 1 ). Results For total bleeding site analysis, GB reduction between T 0 and T 1 ranged from 23% (C), 26% (CX) and 36% (P), respectively (all p < 0.05). Multiple comparison between groups showed that group C was significantly less effective (p < 0.05) than groups CX and P. Splitting the analysis, in patients with severe gingivitis (≥ 30% bleeding sites at T 0 ), all MWs had a positive effect on GB with a reduction at T 1 of 36% (C), 33% (CX) and 42% (P), respectively. While GB reduction between T 0 and T 1 , was significant for all groups, the comparison among groups showed no significant difference between group C and CX, whereas the improvement was significant for group P. On the other hand, in adults with moderate gingivitis (< 30% bleeding sites at T 0 ), only CX and P had a positive effect on GB reduction at T 1 (9% in CX and 2% in P, respectively), although the differences between the three groups were not significant. Conclusion The daily use of MWs with natural components (groups P and CX) for 2 weeks should be considered positively as an adjunct to individual oral prophylaxis to reduce GB compared to the control MW containing CHX 0.12% (group C) in healthy adults with plaque-induced gingivitis. For subjects with severe gingivitis, it is advisable to first use natural MW (P) and then MW based on CHX 0.09% with natural components (CX), compared to MW with CHX 0.12% (C). For adults with moderate gingivitis, P and CX can be advisable, even if no definitive recommendations can be drawn. Trial Registration ACTRN12622000215729, 07/02/2022.