Background: The aims of this clinical study were to evaluate the short-term subjective (by means of questionnaire) and objective (by means of clinical examination) side effects of 0.2% chlorhexidine (CHX) mouthrinse without alcohol used as an adjunct to non-surgical periodontal treatment and to elucidate the relationship between the subjective and objective evaluations.

Methods: This was a randomized, double-blind, placebo-controlled clinical trial with two groups: 1) the test group, rinsing with the test product (0.2% CHX without alcohol) twice per day for 1 week, and 2) the control (placebo) group, rinsing with a placebo solution twice per day for 1 week. Following the start of rinsing, patients were subjectively and objectively evaluated for the presence and severity of side effects (pain, burning sensation, pruritus, dryness of mouth, taste disturbance, mucosal irritations, and discoloration of tooth and tongue surfaces) at days 1, 3, and 7 of the rinsing period. The presence of subjective and objective side effects of the groups was compared via use of χ² and Fisher exact tests. Analysis of the subjective and objective side effects within the evaluation periods was done by McNemar test. Spearman correlation analysis was used to assess the relationships between the subjective and objective side effects.

Results: None of the patients in either group complained of dryness of the mouth. The most commonly reported side effect was the change in color of the labial and buccal mucosa, particularly of the gingiva, after day 3 of rinsing. There were significant (r = 0.308 to 0.835; P <0.05) correlations between the discolorations of tongue and tooth surfaces reported by the patients and clinically detected at all evaluation periods. There was a significant and positive relationship between the subjective side effects and the soft tissue irritations when the duration of rinsing increased.

Conclusion: Within the limits of this clinical evaluation, rinsing with 0.2% alcohol-free CHX for 1 week caused more irritation to oral mucosa, greater burning sensation, and increased altered taste perception compared to the placebo rinse.