Chlorhexidine is one of the most frequently used active agents in oral care and disinfection products. Known for its broad-spectrum antimicrobial activity, it plays an essential role in both preventive and therapeutic dental practices. This article outlines the chemical nature, mechanism of action, clinical applications, and contraindications associated with chlorhexidine use.
What is chlorhexidine and how does it work?
Chlorhexidine is a synthetic organic compound and antiseptic agent belonging to the biguanide group. It was discovered in the 1950s during research on antimalarial drugs. In pharmaceutical and dental products, it is most commonly used in the form of chlorhexidine gluconate or acetate.
It exhibits strong bactericidal activity against Gram-positive bacteria and moderate activity against Gram-negative species. Additionally, it has antifungal, antiviral, and antiplaque properties. Chlorhexidine acts by disrupting microbial cell membranes, leading to leakage of intracellular components and cell death. It is also effective against protozoa, yeasts, and viruses such as HIV, herpes simplex, influenza, and cytomegalovirus.
Chlorhexidine has low systemic toxicity and is excreted unchanged via the kidneys. In the oral cavity, its antimicrobial effect persists for approximately 8 hours, and it can remain active in saliva for up to 12 hours. It binds readily to tissue proteins in the skin and mucosa, prolonging its activity through a process known as substantivity.
Its effectiveness increases when used in combination with alcohol, although its activity is limited against acid-fast bacilli, bacterial spores, and certain strains of Pseudomonas and Proteus.
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Clinical applications of chlorhexidine
Chlorhexidine is incorporated into a wide range of medical, dental, and veterinary products, including:
- Preoperative and postoperative skin disinfectants
- Antiseptic rinses for surgical fields
- Veterinary periodontal treatments for dogs and cats
- Lozenges with vitamin C – for pharyngitis
- Lozenges with benzocaine – for aphthous ulcers, pharyngitis, and oral mucositis
- Disinfectant solutions for hygienic and surgical handwashing
- Irrigation solutions for bladder flushing and gynecological procedures
- Dental gels – for mucosal abrasions, gingival inflammation, and post-operative care
- Combination with dexpanthenol – for wound care, burns, and dermatological inflammation
- Combination with lidocaine – in lozenges, gels, and sprays for oral and throat pain relief
- Combination with sage extract – as an oral gel with antimicrobial and anti-inflammatory effects
- Mouthwashes – for the prevention of dental caries, alveolar osteitis, periodontitis, aphthous ulcers, and post-surgical irritation
Contraindications and precautions
Use of chlorhexidine is contraindicated in the following situations:
- Known hypersensitivity or allergic reactions
- Breastfeeding
- ENT (ear, nose, throat) surgical procedures
- Neurosurgical procedures involving contact with cerebrospinal fluid
Allergic reactions may present as respiratory distress and severe skin rash, requiring immediate administration of antihistamines. It is crucial to avoid contact between chlorhexidine and the eyes. Caution is advised during application to prevent irritation or chemical injury.
