chlorhexidin

Chlorhexidine, commonly supplied as chlorhexidine gluconate, is a cationic antiseptic and disinfectant belonging to the bisbiguanide class. It has broad-spectrum antimicrobial activity and is used to reduce microbial burden on skin, mucous membranes, and wounds.

Mechanism of action: The positively charged chlorhexidine molecules bind to negatively charged bacterial surfaces and cell walls, disrupting membranes and causing leakage of cellular contents. The compound also binds to keratin, giving residual antimicrobial activity on skin and mucosal surfaces.

Spectrum and activity: It is active against many Gram-positive and Gram-negative bacteria, some yeasts, and most enveloped viruses. It is not active against bacterial spores. Its substantivity contributes to prolonged antimicrobial effects after application.

Forms and medical uses: Available in solutions, rinses, gels, and impregnated devices. Common uses include preoperative skin preparation, surgical hand antisepsis, body washes for antiseptic cleansing, and wound care. In dentistry, 0.12% chlorhexidine mouthwash is used to reduce plaque and gingivitis. Concentrations vary by indication, with higher concentrations used for skin disinfection and lower concentrations for oral care.

Safety and limitations: Chlorhexidine is generally well tolerated but can cause contact dermatitis or irritation in some individuals. Long-term or widespread oral use may cause tooth staining and altered taste. Hypersensitivity reactions are rare but can be serious. Efficacy can be reduced when used with certain anionic products (for example some soaps or toothpaste formulations containing sodium lauryl sulfate); separate timing is advised. It is not effective against bacterial spores.

Contraindications: known hypersensitivity to chlorhexidine; caution in individuals with a history of severe allergies or asthma.