Evidence on antimicrobial mouthwashes for the management of aphthous ulcers is poor. The quality of studies is poor and results are not consistent. Antimicrobial mouthwashes (chlorhexidine, hexetidine, and triclosan) may reduce the duration and severity (degree of pain) of an ulcer episode, and increase the number of ulcer-free days between episodes. However, antimicrobial mouthwashes do not seem to reduce the incidence of ulceration (number of new ulcers).

• A BMJ Clinical Evidence review (search date: August 2006) identified no systematic review investigating the efficacy of antimicrobial mouthwashes for the treatment of recurrent aphthous ulcers. The review identified five randomized controlled trials (RCTs) comparing antimicrobial mouthwashes with inactive controls in a total of 203 people with recurrent aphthous ulcers [Porter and Scully, 2006]. A number of outcomes were studied, so results from the five RCTs were not pooled.
• Ulcer days index (the sum of the number of ulcers each day over a specified period) (three trials, n = 87). In two of these studies (n = 50) the ulcer days index was significantly reduced in people treated with chlorhexidine compared with control. In the third study (n = 37) there was no significant difference between hexetidine and control.
• Number of ulcer-free days (one trial, n = 38). People using chlorhexidine gluconate 0.2% mouthwash had significantly longer ulcer-free periods over 6 weeks compared with control (mean number of ulcer-free days 22.9 vs. 17.5, p < 0.02).
• Duration of ulceration (three trials, n = 95). In one study (n = 20) the mean number of days of ulcer duration was significantly reduced with chlorhexidine 1% gel compared with control (4.8 days vs. 7.8 days, p < 0.01). There was a small, non-significant reduction in ulcer duration in the other two studies.
• Severity of pain (four trials, n = 107). Only two studies found that chlorhexidine significantly reduced the severity of pain compared with control (p < 0.05).
• Incidence of new ulceration (five trials, n = 203). Only one study (n = 12) found that active treatment (chlorhexidine gluconate 0.2%) significantly reduced the number of new ulcers compared with control (p < 0.05). However, this was a crossover study with a high drop-out rate, and it is unclear whether confounding factors were accounted for.
• A recent review identified one further double-blind crossover study of 0.15% triclosan mouthwash (in three different solubilizing agents) compared with control in 30 people with a history of recurrent aphthous ulcers [Skaare et al, 1996]. Study medication was used twice a day, and each crossover study period lasted 6 weeks.
• Severity of pain. Mouthrinses containing triclosan in ethanol/zinc sulphate significantly reduced the mean severity of pain experienced compared with control.
• Number of ulcer-free days. Mouthrinses containing triclosan in ethanol/zinc sulphate significantly reduced the mean number of ulcer-free days compared with control.
• Incidence of ulceration. Mouthrinses containing triclosan significantly reduced the number of new ulcers during the 6-week study periods compared with control.