Chlorhexidine is a

disinfectant A disinfectant is a chemical substance or compound used to inactivate or destroy microorganisms on inert surfaces. Disinfection does not necessarily kill all microorganisms, especially resistant bacterial spores; it is less effective than ...

and

antiseptic An antiseptic ( and ) is an antimicrobial substance or compound that is applied to living tissue to reduce the possibility of sepsis, infection, or putrefaction. Antiseptics are generally distinguished from ''antibiotics'' by the latter's abil ...

which is used for

skin disinfection Skin disinfection is a process that involves the application of a disinfectant to reduce levels of microorganisms on the skin. Disinfecting the skin of the patient and the hands of the healthcare providers are an important part of surgery. Skin di ...

before surgery and to disinfect

surgical instruments A surgical instrument is a medical device for performing specific actions or carrying out desired effects during a surgery or operation, such as modifying biological tissue, or to provide access for viewing it. Over time, many different kinds of ...

. It is also used for cleaning

wounds A wound is any disruption of or damage to living tissue, such as skin, mucous membranes, or organs. Wounds can either be the sudden result of direct trauma (mechanical, thermal, chemical), or can develop slowly over time due to underlying diseas ...

, preventing

dental plaque Dental plaque is a biofilm of microorganisms (mostly bacteria, but also fungi) that grows on surfaces within the mouth. It is a sticky colorless deposit at first, but when it forms Calculus (dental), tartar, it is often brown or pale yellow. It is ...

, treating yeast infections of the mouth, and to keep urinary catheters from blocking. It is used as a

liquid Liquid is a state of matter with a definite volume but no fixed shape. Liquids adapt to the shape of their container and are nearly incompressible, maintaining their volume even under pressure. The density of a liquid is usually close to th ...

or a powder. It is commonly used in

salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

form, either the gluconate or the

acetate An acetate is a salt formed by the combination of acetic acid with a base (e.g. alkaline, earthy, metallic, nonmetallic, or radical base). "Acetate" also describes the conjugate base or ion (specifically, the negatively charged ion called ...

. Side effects may include skin irritation,

tooth A tooth (: teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tea ...

discoloration, and

allergic reactions Allergies, also known as allergic diseases, are various conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic dermatitis, alle ...

, 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 Pregnancy is the time during which one or more offspring gestation, gestates inside a woman's uterus. A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Conception (biology), Conception usually occurs ...

appears to be safe. Chlorhexidine may come mixed in

alcohol Alcohol may refer to: Common uses * Alcohol (chemistry), a class of compounds * Ethanol, one of several alcohols, commonly known as alcohol in everyday life ** Alcohol (drug), intoxicant found in alcoholic beverages ** Alcoholic beverage, an alco ...

, water, or surfactant solution. It is effective against a range of

microorganisms A microorganism, or microbe, is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells. The possible existence of unseen microbial life was suspected from antiquity, with an early attestation in ...

, but does not inactivate

spores In biology, a spore is a unit of sexual (in fungi) or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plant ...

. Chlorhexidine came into medical use in the 1950s and is available over the counter in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

. It is on the

World Health Organization's List of Essential Medicines The WHO Model List of Essential Medicines (aka Essential Medicines List or EML), published by the World Health Organization (WHO), contains the medications considered to be most effective and safe to meet the most important needs in a health s ...

. In 2022, it was the 230th most commonly prescribed medication in the United States, with more than 1million prescriptions.

Uses

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 Endodontics () is the Specialty (dentistry), dental specialty concerned with the study and treatment of the dental pulp. Overview Endodontics encompasses the study (practice) of the basic and clinical sciences of normal dental pulp, the etiolo ...

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

Antiseptic

Chlorhexidine is active against

Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. The Gram stain is ...

and

Gram-negative Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ...

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 Poliovirus, the causative agent of polio (also known as poliomyelitis), is a serotype of the species ''Enterovirus C'', in the family of ''Picornaviridae''. There are #Origin and serotypes, three poliovirus serotypes, numbered 1, 2, and 3. Pol ...

and

adenoviruses Adenoviruses (members of the family ''Adenoviridae'') are medium-sized (90–100 nm), nonenveloped (without an outer lipid bilayer) viruses with an icosahedral nucleocapsid containing a double-stranded DNA genome. Their name derives from the ...

. 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 Surgery is a medical specialty that uses manual and instrumental techniques to diagnose or treat pathological conditions (e.g., trauma, disease, injury, malignancy), to alter bodily functions (e.g., malabsorption created by bariatric surgery s ...

. 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.

Dental use

Use of a chlorhexidine-based mouthwash in combination with normal tooth care can help reduce the build-up of plaque and improve mild

gingivitis Gingivitis is a non-destructive disease that causes inflammation of the gums; ulitis is an alternative term. The most common form of gingivitis, and the most common form of periodontal disease overall, is in response to bacterial biofilms (also ...

. There is not enough evidence to determine the effect in moderate to severe gingivitis. Its use as a mouthwash has a number of

adverse effect An adverse effect is an undesired harmful effect resulting from a medication or other intervention, such as surgery. An adverse effect may be termed a "side effect", when judged to be secondary to a main or therapeutic effect. The term compli ...

s including damage to the mouth lining, tooth discoloration, tartar build-up, and impaired taste. Extrinsic tooth staining occurs when chlorhexidine rinse has been used for four weeks or longer. Mouthwashes containing chlorhexidine which stain teeth less than the classic solution have been developed, many of which contain chelated

zinc Zinc is a chemical element; it has symbol Zn and atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic tabl ...

. Chlorhexidine is a

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

which interacts with

anionic An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

components of

toothpaste Toothpaste is a paste or gel dentifrice that is used with a toothbrush to clean and maintain the aesthetics of Human tooth, teeth. Toothpaste is used to promote oral hygiene: it is an abrasive that aids in removing dental plaque and food from th ...

, such as

sodium lauryl sulfate Sodium dodecyl sulfate (SDS) or sodium lauryl sulfate (SLS), sometimes written sodium laurilsulfate, is an organic compound with the formula and structure . It is an anionic surfactant used in many cleaning and hygiene products. This compound ...

and sodium monofluorophosphate, and forms salts of low solubility and reduced antibacterial activity. Hence, to enhance the antiplaque effect of chlorhexidine, "it seems best that the interval between toothbrushing and rinsing with CHX hlorhexidinebe more than 30 minutes, cautiously close to two hours after brushing".

Topical

Chlorhexidine gluconate is used as a skin cleanser for surgical scrubs, as a cleanser for skin wounds, for preoperative skin preparation, and for germicidal hand rinses. Chlorhexidine

eye drop Eye drops or eyedrops are liquid drops applied directly to the surface of the eye usually in small amounts such as a single drop or a few drops. Eye drops usually contain saline to match the salinity of the eye. Drops containing only saline ...

s have been used as a treatment for eyes affected by ''Acanthamoeba'' keratitis. Chlorhexidine is a very effective antiseptic and its use is growing in the world for treating the umbilical cord. A 2015

Cochrane review Cochrane is a British international charitable organisation formed to synthesize medical research findings to facilitate evidence-based choices about health interventions involving health professionals, patients and policy makers. It includes ...

has yielded high-quality evidence that within the community setting, chlorhexidine skin or cord care can reduce the incidence of omphalitis (inflammation of the

umbilical cord In Placentalia, placental mammals, the umbilical cord (also called the navel string, birth cord or ''funiculus umbilicalis'') is a conduit between the developing embryo or fetus and the placenta. During prenatal development, the umbilical cord i ...

) by 50% and neonatal mortality by 12%.

Side effects

Side effects may include skin irritation,

discoloration, and

, although apart from discoloration the risk appears to be the same as povidone-iodine. Chlorhexidine is ototoxic (toxic to the inner ear). If put into a ruptured ear canal it may lead to deafness. Chlorhexidine does not meet European specifications for a hand disinfectant. Under the test conditions of the

European Standard European Standards, sometimes called Euronorm (abbreviated EN, from the German name , "European Norm"), are technical standards which have been ratified by one of the three European Standards Organizations (ESO): European Committee for Standardizat ...

EN 1499, no significant difference in the efficacy was found between a 4% solution of chlorhexidine digluconate and soap. In the US, between 2007 and 2009, Hunter Holmes McGuire Veterans Administration Medical Center conducted a cluster-randomized trial and concluded that daily bathing of patients in intensive care units with washcloths saturated with chlorhexidine gluconate reduced the risk of hospital-acquired infections. Whether prolonged exposure over many years may have carcinogenic potential is still not clear. The US

Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respo ...

recommendation is to limit the use of a chlorhexidine gluconate mouthwash to a maximum of six months. When ingested, chlorhexidine is poorly absorbed in the gastrointestinal tract and can cause stomach irritation or nausea. If aspirated into the lungs at high enough concentration, as reported in one case, it can be fatal due to the high risk of

acute respiratory distress syndrome Acute respiratory distress syndrome (ARDS) is a type of respiratory failure characterized by rapid onset of widespread inflammation in the lungs. Symptoms include shortness of breath (dyspnea), rapid breathing (tachypnea), and bluish skin co ...

Mechanism of action

At physiologic pH, chlorhexidine salts dissociate and release the positively charged chlorhexidine

. The bactericidal effect is a result of the binding of this cationic molecule to negatively charged bacterial cell walls. At low concentrations of chlorhexidine, this results in a

bacteriostatic A bacteriostatic agent or bacteriostat, abbreviated Bstatic, is a biological or chemical agent that stops bacteria from reproducing, while not necessarily killing them otherwise. Depending on their application, bacteriostatic antibiotics, disinfec ...

effect; at high concentrations, membrane disruption results in cell death.

Chemistry

It is a cationic ( bisbiguanide).

Deactivation

Chlorhexidine is deactivated by forming insoluble salts with

compounds, including the anionic

surfactants Surfactants are chemical compounds that decrease the surface tension or interfacial tension between two liquids, a liquid and a gas, or a liquid and a solid. The word ''surfactant'' is a blend of "surface-active agent", coined in 1950. As t ...

commonly used as detergents in toothpastes and mouthwashes, anionic thickeners such as

carbomer Poly(acrylic acid) (PAA; trade name Carbomer) is a polymer with the formula (CH2−CHCO2H)''n''. It is a derivative of acrylic acid (CH2=CHCO2H). In addition to the homopolymers, a variety of copolymers and crosslinked polymers, and partially de ...

, and anionic

emulsifiers An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids. Although ...

such as acrylates/C10-30 alkyl acrylate , among many others. For this reason, chlorhexidine mouth rinses should be used at least 30 minutes after other dental products.

Synthesis

The structure is based on two molecules of proguanil, linked with a hexamethylenediamine spacer. Chlorhexidine synthesis

Society and culture

Brands

Chlorhexidine topical is sold as Betasept, Biopatch, Calgon Vesta, ChloraPrep One-Step, Dyna-Hex, Hibiclens, Hibistat Towelette, Scrub Care Exidine, and Spectrum-4, among others. Chlorhexidine gluconate mouthwash is sold as Dentohexin, Paroex, Peridex, PerioChip, Corsodyl and Periogard, among others.

Veterinary medicine

In animals, chlorhexidine is used for topical disinfection of wounds, and to manage skin infections. Chlorhexidine-based disinfectant products are used in the dairy farming industry. Post-surgical respiratory problems have been associated with the use of chlorhexidine products in cats.

References

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