Side effects may include skin irritation,tooth discoloration, andallergic reactions,[3] although, apart from discoloration, the risk appears to be the same as that forpovidone-iodine.[6][7] 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.[8] It may cause eye problems if direct contact occurs.[9][10] Use inpregnancy appears to be safe.[11] Chlorhexidine may come mixed inalcohol,[12][13][14] water, orsurfactant solution.[3] It is effective against a range ofmicroorganisms, but does not inactivatespores.[2]
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).[19]
Inendodontics, chlorhexidine has been used for root canal irrigation and as an intracanal dressing.[20][21]
Chlorhexidine is active againstGram-positive andGram-negative organisms,facultative anaerobes,aerobes, and yeasts.[22] 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 againstpolioviruses andadenoviruses. The effectiveness against herpes viruses has not yet been established unequivocally.[23]
There is strong evidence that chlorhexidine is more effective thanpovidone-iodine for cleansurgery.[24][25] Evidence shows that it is an effective antiseptic for upper limb surgery.[6]
Meta-data spanning several decades shows that the efficacy of chlorhexidine (against organisms that cause surgical site infection) has not changed,[26] dispelling concerns over emerging resistance.
Use of a chlorhexidine-based mouthwash in combination with normal tooth care can help reduce the build-up of plaque and improve mildgingivitis.[27] There is not enough evidence to determine the effect in moderate to severe gingivitis.[27] Its use as a mouthwash has a number ofadverse effects including damage to the mouth lining, tooth discoloration,tartar build-up, and impaired taste.[27] Extrinsic tooth staining occurs when chlorhexidine rinse has been used for four weeks or longer.[27]
Mouthwashes containing chlorhexidine which stain teeth less than the classic solution have been developed, many of which containchelatedzinc.[28][29][30]
Chlorhexidine is acation which interacts withanionic components oftoothpaste, such assodium lauryl sulfate andsodium 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 [chlorhexidine] be more than 30 minutes, cautiously close to two hours after brushing".[31]
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.[22] Chlorhexidineeye drops have been used as a treatment for eyes affected byAcanthamoeba keratitis.[32]
Chlorhexidine is a very effective antiseptic and its use is growing in the world for treating the umbilical cord. A 2015Cochrane review has yielded high-quality evidence that within the community setting, chlorhexidine skin or cord care can reduce the incidence ofomphalitis (inflammation of theumbilical cord) by 50% and neonatal mortality by 12%.[33]
Chlorhexidine isototoxic (toxic to the inner ear). If put into a ruptured ear canal it may lead to deafness.[34]
Chlorhexidine does not meet European specifications for a hand disinfectant. Under the test conditions of theEuropean Standard EN 1499, no significant difference in the efficacy was found between a 4% solution of chlorhexidine digluconate and soap.[23] 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.[35]
Whether prolonged exposure over many years may have carcinogenic potential is still not clear. The USFood and Drug Administration recommendation is to limit the use of a chlorhexidine gluconate mouthwash to a maximum of six months.[36]
When ingested, chlorhexidine is poorly absorbed in the gastrointestinal tract and can cause stomach irritation or nausea.[37][38] If aspirated into the lungs at high enough concentration, as reported in one case, it can be fatal due to the high risk ofacute respiratory distress syndrome.[38][39]
At physiologicpH, chlorhexidine salts dissociate and release the positively charged chlorhexidinecation. 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 abacteriostatic effect; at high concentrations, membrane disruption results in cell death.[22]
Chlorhexidine is deactivated by forming insoluble salts withanionic compounds, including the anionicsurfactants commonly used as detergents in toothpastes and mouthwashes, anionicthickeners such ascarbomer, and anionicemulsifiers such as acrylates/C10-30 alkyl acrylate crosspolymer, among many others. For this reason, chlorhexidine mouth rinses should be used at least 30 minutes after other dental products.[41]
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.[43]
Chlorhexidine gluconate mouthwash is sold as Dentohexin, Paroex, Peridex, PerioChip, Corsodyl and Periogard, among others.[44]
In animals, chlorhexidine is used for topical disinfection of wounds,[45] and to manage skin infections.[46] Chlorhexidine-based disinfectant products are used in the dairy farming industry.[47]
Post-surgical respiratory problems have been associated with the use of chlorhexidine products in cats.[48]
^World Health Organization (2023).The selection and use of essential medicines 2023: web annex A: World Health Organization model list of essential medicines: 23rd list (2023). Geneva: World Health Organization.hdl:10665/371090. WHO/MHP/HPS/EML/2023.02.
^Bernardi F, Pincelli MR, Carloni S, Gatto MR, Montebugnoli L (August 2004). "Chlorhexidine with an Anti Discoloration System. A comparative study".International Journal of Dental Hygiene.2 (3):122–126.doi:10.1111/j.1601-5037.2004.00083.x.PMID16451475.
^Sanz M, Vallcorba N, Fabregues S, Müller I, Herkströter F (July 1994). "The effect of a dentifrice containing chlorhexidine and zinc on plaque, gingivitis, calculus and tooth staining".Journal of Clinical Periodontology.21 (6):431–437.doi:10.1111/j.1600-051X.1994.tb00741.x.PMID8089246.
^Kumar S, Patel S, Tadakamadla J, Tibdewal H, Duraiswamy P, Kulkarni S (February 2013). "Effectiveness of a mouthrinse containing active ingredients in addition to chlorhexidine and triclosan compared with chlorhexidine and triclosan rinses on plaque, gingivitis, supragingival calculus and extrinsic staining".International Journal of Dental Hygiene.11 (1):35–40.doi:10.1111/j.1601-5037.2012.00560.x.PMID22672130.
^Kolahi J, Soolari A (September 2006). "Rinsing with chlorhexidine gluconate solution after brushing and flossing teeth: a systematic review of effectiveness".Quintessence International.37 (8):605–612.PMID16922019.
^Below H, Assadian O, Baguhl R, Hildebrandt U, Jäger B, Meissner K, et al. (February 2017). "Measurements of chlorhexidine, p-chloroaniline, and p-chloronitrobenzene in saliva after mouth wash before and after operation with 0.2% chlorhexidine digluconate in maxillofacial surgery: a randomised controlled trial".The British Journal of Oral & Maxillofacial Surgery.55 (2):150–155.doi:10.1016/j.bjoms.2016.10.007.PMID27789177.
^ab"Chlorhexidine".Pubchem. U.S. National Library of Medicine.Archived from the original on 5 July 2018. Retrieved4 July 2018.
^Hirata K, Kurokawa A (April 2002). "Chlorhexidine gluconate ingestion resulting in fatal respiratory distress syndrome".Veterinary and Human Toxicology.44 (2):89–91.PMID11931511.An 80-y-old woman with dementia accidentally ingested approximately 200 mL of Maskin (5% chlorhexidine) in a nursing home and then presumably aspirated gastric contents.
^Rose FL, Swain G (1956). "850. Bisdiguanides having antibacterial activity".Journal of the Chemical Society (Resumed):4422–4425.doi:10.1039/JR9560004422.
^van Hengel T, ter Haar G, Kirpensteijn J (2013). "Chapter 2. Wound management: a new protocol for dogs and cats. Chlorhexidine solution". In Kirpensteijn J, ter Haar G (eds.).Reconstructive Surgery and Wound Management of the Dog and Cat. CRC Press.ISBN9781482261455.
^Maddison JE, Page SW, Church DB, eds. (2008). "Antimicrobial agents. Chlorhexidine".Small Animal Clinical Pharmacology. Elsevier Health Sciences. p. 552.ISBN978-0702028588.
^Blowey RW, Edmondson P (2010).Mastitis Control in Dairy Herds. CABI. p. 120.ISBN9781845937515.
