Chlorhexidine

Chlorhexidine is a disinfectant and antiseptic which is used for skin disinfection before surgery and to disinfect surgical instruments. It is also used for cleaning wounds, preventing dental plaque, treating yeast infections of the mouth, and to keep urinary catheters from blocking. It is used as a liquid or a powder. It is commonly used in salt form, either the gluconate or the acetate.

Side effects may include skin irritation, tooth discoloration, and allergic reactions, although, apart from discoloration, the risk appears to be the same as that for povidone-iodine. Chlorhexidine rinse is also known to have a bitter metallic aftertaste. Rinsing with water is not recommended as it is known to increase the bitterness. It may cause eye problems if direct contact occurs. Use in pregnancy appears to be safe. Chlorhexidine may come mixed in alcohol, water, or surfactant solution. It is effective against a range of microorganisms, but does not inactivate spores.

Chlorhexidine came into medical use in the 1950s and is available over the counter in the United States. It is on the World Health Organization's List of Essential Medicines. In 2023, it was the 270th most commonly prescribed medication in the United States, with more than 900,000 prescriptions.

Chlorhexidine is used in disinfectants (disinfection of the skin and hands), cosmetics (additive to creams, toothpaste, deodorants, and antiperspirants), and pharmaceutical products (preservative in eye drops, active substance in wound dressings and antiseptic mouthwashes).

In endodontics, chlorhexidine has been used for root canal irrigation and as an intracanal dressing.

Chlorhexidine is active against Gram-positive and Gram-negative organisms, facultative anaerobes, aerobes, and yeasts. It is particularly effective against Gram-positive bacteria (in concentrations ≥ 1 μg/L). Significantly higher concentrations (10 to more than 73 μg/mL) are required for Gram-negative bacteria and fungi. Chlorhexidine is ineffective against polioviruses and adenoviruses. The effectiveness against herpes viruses has not yet been established unequivocally.

There is strong evidence that chlorhexidine is more effective than povidone-iodine for clean surgery. Evidence shows that it is an effective antiseptic for upper limb surgery.

Meta-data spanning several decades shows that the efficacy of chlorhexidine (against organisms that cause surgical site infection) has not changed, dispelling concerns over emerging resistance.