Chlorhexidine

Chlorhexidine is bactericidal and fungicidal, and has activity against some viruses. Chlorhexidine adsorbs onto oral surfaces so is effective over a prolonged period. It prevents plaque formation on a clean tooth surface, but does not reduce pre-existing plaque.

Intraoral chlorhexidine formulations include mouthwash (as chlorhexidine gluconate in concentrations of 0.12% and 0.2%), gel and a slow-release formulation for local delivery into periodontal pockets.

It was previously thought that chlorhexidine mouthwash was inactivated by the detergent sodium lauryl sulfate used in standard toothpaste; however, research has shown this is not the case. Although it is unlikely that there is an interaction between sodium lauryl sulfate and chlorhexidine gel, further evidence is required to confirm this.

Chlorhexidine can cause skin reactions, irritate mucosal surfaces and interrupt wound healing. Intraoral use can cause a burning sensation, altered taste and increased calculus formation; it can also cause brown discolouration of the teeth, tongue, buccal cavity and margins of dental restorations. Extrinsic staining is not permanent and can be professionally removed from the teeth. Chlorhexidine is usually recommended for short periods of up to 2 weeks to minimise adverse effects.

Chlorhexidine allergy has been reported, sometimes so severe as to be life threatening. If a patient reports a history of allergy to chlorhexidine, it must be avoided via all routes of administration, including topical application.