Chlorhexidine

How it works

It is a cationic biguanide that binds to and disrupts negatively charged bacterial cell membranes, giving broad-spectrum bactericidal activity against many Gram-positive and Gram-negative organisms.

Prescribing in practice

• Anaphylactic and other hypersensitivity reactions to chlorhexidine can occur, including with medical devices and antiseptic skin preparations, so be alert to this risk and avoid use in patients with known sensitivity.
• Alcohol-based skin preparations are flammable, so allow the solution to dry fully and avoid pooling before using diathermy or other ignition sources.
• Avoid contact with the eyes, brain, meninges and middle ear, and use mouthwash formulations as directed as they can cause reversible tooth and tongue staining and taste disturbance.

Monitoring

Routine laboratory monitoring is not required; observe for local irritation and for any signs of hypersensitivity.

Counselling the patient

• Use externally or as a mouthwash exactly as directed and avoid getting it in the eyes.
• Mouthwash may cause temporary staining of the teeth and altered taste, which generally resolves on stopping.
• Stop and seek advice if rash, swelling or breathing difficulty develops.

Evidence & guidelines

Chlorhexidine is a long-established antiseptic supported by extensive clinical use and infection-control evidence.