Chlorhexidine digluconate (CHG) is a powerful and widely recognized antiseptic agent used extensively in healthcare and personal hygiene products. This compound is classified chemically as a cationic bisbiguanide, meaning it carries a positive electrical charge. Its primary function is to inhibit the growth of and eliminate a broad range of microorganisms, including many types of bacteria, fungi, and certain viruses.
Understanding Its Mechanism of Action
CHG exerts its antimicrobial effect through direct interaction with the outer surfaces of microbial cells. The positively charged CHG molecule is attracted to the negatively charged components, primarily phosphate groups, found on the cell walls of bacteria and fungi. This electrostatic attraction causes CHG to bind strongly and rapidly to the microbial cell surface. The binding process destabilizes the structural integrity of the cell wall, allowing the antiseptic to penetrate the cell.
At lower concentrations, this initial membrane damage causes the leakage of small substances, such as potassium ions, from the microbe. This leakage compromises the cell’s internal environment, resulting in bacteriostatic action, where microbial growth is inhibited. At higher concentrations, the mechanism becomes immediately lethal, known as bactericidal action, which rapidly kills the microorganism. The concentrated CHG molecules penetrate the cell membrane and interact with the cytoplasm. This interaction causes the cytoplasmic contents, including proteins and nucleic acids, to congeal or precipitate, leading to irreversible damage and the rapid demise of the microbial cell.
Primary Applications in Medical and Oral Care
The unique ability of CHG to bind to tissues and retain its antimicrobial activity, a property known as substantivity, makes it invaluable in medical and oral health contexts. In medical and surgical settings, CHG is widely used for pre-operative skin preparation to reduce the risk of surgical site infections. It is commonly applied as a topical solution, wash, or swab for disinfecting the patient’s skin before injections or procedures.
Healthcare providers also use CHG for handwashing and for preparing the insertion sites for central venous catheters and other intravascular devices. This application is beneficial because the residual effect of CHG on the skin provides continued protection against potential pathogens. Different concentrations are formulated for these purposes, such as 2% or 4% solutions, often combined with alcohol to enhance the speed and effectiveness of the kill rate. CHG is also incorporated into wound dressings and used for cleansing wounds to prevent bacterial colonization and promote healing.
In the oral health field, CHG is primarily encountered as a prescription mouthwash, typically at a 0.12% concentration, or as an oral chip designed for insertion into periodontal pockets. This oral rinse is prescribed for the short-term management of gingivitis, a common gum disease characterized by inflammation and bleeding. For more advanced conditions, such as periodontitis, CHG may be used as an adjunct therapy to professional dental cleaning procedures.
The compound’s substantivity allows it to slowly release onto the oral tissues and tooth surfaces, providing a prolonged period of antimicrobial action in the oral cavity. While highly effective at managing bacterial plaque, it does not prevent the formation of plaque or tartar. Therefore, its use must supplement regular brushing and flossing.
Safety Profile and Adverse Reactions
CHG is generally considered to have low toxicity when used correctly, but it is associated with a range of side effects and requires specific precautions. The most common, mild side effects are usually related to its use in the mouth, including temporary changes in taste perception. Users of CHG mouthwash may also notice extrinsic staining of the teeth and tongue, which appears as a brown or yellowish discoloration. Topical application can sometimes lead to localized skin irritation or contact dermatitis.
Proper application is important, and for skin preparations, care must be taken to avoid contact with the eyes, middle ear, and meninges. The most serious, though rare, adverse reaction is a severe allergic response known as anaphylaxis. Anaphylactic reactions are sudden, potentially life-threatening, and can occur within minutes of exposure to the skin or oral mucosa. Symptoms of this severe hypersensitivity include difficulty breathing, wheezing, swelling of the face, or a rapidly progressing rash.
Due to an increase in reported cases of anaphylaxis, the U.S. Food and Drug Administration (FDA) has requested that manufacturers of over-the-counter CHG products add a warning about this risk to their labels. Healthcare professionals are advised to ask patients about any previous allergic reactions to antiseptics before recommending or prescribing a product containing chlorhexidine digluconate.