Chlorhexidine

What it is

Chlorhexidine is a synthetic bisbiguanide antiseptic, used as the gluconate (digluconate) salt. It is formulated as a 0.12% or 0.2% mouthrinse, as 2% and 4% skin cleansers and impregnated wipes, and as an alcohol-containing surgical skin preparation. It is a topical agent: the oral rinse label states that chlorhexidine gluconate is poorly absorbed from the gut, so systemic exposure after rinsing or washing is low. It is not a nutrient and the body does not make it.

What the research says

For the use with the strongest evidence - mouthrinse added to tooth brushing - Cochrane-rated high-quality evidence shows a large reduction in dental plaque, but the accompanying reduction in gingivitis in people with mild gum inflammation was judged by the review authors not to be clinically relevant, and tooth staining is near-universal with four weeks or more of use. For washing patients in hospital, pooled observational and trial data show lower rates of hospital-acquired bloodstream infection, but the studies are heterogeneous and mostly not blinded. For routine oral care in hospital inpatients generally, a large hospital-wide cohort found chlorhexidine exposure associated with higher mortality, so benefit outside specific populations is unproven. The main harms are tooth and tongue staining, taste disturbance, mucosal soreness, and rare but real anaphylaxis.

Evidence grade: Disputed.

How it works

Drug class: Bisbiguanide topical antiseptic / antimicrobial (cationic antiseptic)

Chlorhexidine is a positively charged molecule that sticks to the negatively charged surfaces of teeth, mucosa and bacterial cell walls, and kills or suppresses bacteria on contact. Because it binds to oral surfaces it keeps working between rinses, and microbiological sampling of plaque has shown a general reduction in bacterial counts of 54-97% through six months of use, although the label states that the clinical significance of this antimicrobial activity is not clear. Very little is absorbed into the bloodstream from the mouth or gut. (Source 1)

What it is used for

• High-quality Cochrane evidence shows a large reduction in plaque at 4 to 6 weeks and at 6 months. The parallel reduction in gingivitis, in people whose gums were only mildly inflamed to begin with, was 0.21 points on a 0 to 3 scale and the review authors judged it not clinically relevant. Evidence: established. (Source 2)
• A 2019 systematic review of 26 studies reported a markedly lower incidence of hospital-acquired bloodstream infection with chlorhexidine bathing (IRR 0.59, 95% CI 0.52-0.68), in both ICU and non-ICU settings. Most contributing studies were not blinded and reported incidence rates rather than individually randomised patient outcomes, so confounding by concurrent infection-control changes cannot be excluded. Evidence: limited. (Source 3)
• A hospital-wide cohort of 82,274 patients found that low-level chlorhexidine oral-care exposure was associated with a higher risk of death, with the association strongest in patients at lowest baseline risk. This is observational and cannot establish cause, but the authors concluded the data argue against indiscriminate widespread use. Evidence: disputed. (Source 4)

Interactions

• Sodium lauryl sulphate (SLS) toothpaste (clinical trial): It is widely claimed that detergent in toothpaste inactivates chlorhexidine, so rinsing should be separated from brushing. A systematic review of four studies with nine comparisons found no significant difference in plaque inhibition when sodium lauryl sulphate toothpaste was used as a paste with chlorhexidine mouthwash, regardless of the order of use, but did find a significant difference when the toothpaste was used as a slurry rinse; the authors graded the recommendation as moderate. Limit: The abstract is hard to read on one point: for toothpaste used as a slurry rinse it says the 'interference' with chlorhexidine's plaque-inhibiting effect was 'significantly decreased' (MD 0.33), while its conclusions treat the slurry result as a sign of interference, so the wording should not be taken to mean the slurry was harmless. The confidence interval printed for the paste result (-0.26 to 0.11) is not centred on the stated difference of 0.08, so those exact numbers should be treated with caution. The 'no interference' conclusion applies to toothpaste used as a normal paste, rests on four studies, and the authors grade it only moderate because three of the four came from the same research group. (Source 5)
• Oral and gut absorption (relevant to swallowed product and to interactions by that route) (label): Chlorhexidine is poorly absorbed from the gastrointestinal tract, which is why swallowed traces produce little systemic drug exposure and why no food interaction acting through blood levels has been established. (Source 1)

Stopping it

• Nothing in the literature read describes physical dependence or a withdrawal syndrome on stopping chlorhexidine; it is a topical antiseptic with minimal absorption. The deprescribing question that is actually studied is whether routine use should continue at all: a hospital-wide cohort that found chlorhexidine oral care associated with higher mortality concluded against indiscriminate use outside populations with proven benefit. (Source 4)
• Staining is a consequence of continued use rather than of stopping: the Cochrane review states that rinsing for four weeks or longer causes extrinsic tooth staining, which is an argument used for limiting courses rather than continuing indefinitely. (Source 2)

What goes wrong

Chlorhexidine mouthrinse causes a large increase in extrinsic tooth staining. (Source 2)

• Systematic review, Moderate certainty.
• Size: 415 participants across eight trials.
• Who: Mouthrinse users in randomised trials.
• How long: 4 to 6 weeks.
• Result: SMD 1.07 standard deviations more staining (95% CI 0.80 to 1.34), moderate-quality evidence.
• Funding: independent (Cochrane Oral Health)

There was a large increase in extrinsic tooth staining in participants using chlorhexidine mouthrinse at 4 to 6 weeks. The SMD was 1.07 (95% CI 0.80 to 1.34) standard deviations higher (eight trials, 415 participants analysed, moderate-quality evidence) in the chlorhexidine mouthrinse group.

Taste disturbance, oral mucosal soreness, irritation, desquamation and ulceration, and a burning sensation or burning tongue were the adverse effects most often reported in chlorhexidine mouthrinse trials. (Source 2)

• Systematic review, Low certainty.
• Size: 51 included studies; taste disturbance reported in 11, mucosal effects in 13, burning sensation or burning tongue in nine.
• Who: Mouthrinse trial participants.
• How long: 4 weeks to 6 months.
• Result: Counts of studies reporting each effect; the review does not pool incidence rates against placebo.
• Funding: independent (Cochrane Oral Health)

The adverse effects most commonly reported in the included studies were taste disturbance/alteration (reported in 11 studies), effects on the oral mucosa including soreness, irritation, mild desquamation and mucosal ulceration/erosions (reported in 13 studies) and a general burning sensation or a burning tongue or both (reported in nine studies).

In a hospital-wide cohort, chlorhexidine oral care was associated with an increased risk of death, most strongly in the patients at lowest baseline risk. (Source 4)

• Cohort study, Low certainty.
• Size: 82,274 patients, of whom 11,133 (14%) received chlorhexidine oral care.
• Who: All adult inpatients at one hospital.
• How long: hospital admission.
• Result: OR 2.61 (95% CI 2.32-2.92) for low-level exposure (300 mg or less); OR 5.50 (95% CI 4.51-6.71) in minor/moderate-risk patients, OR 2.33 (95% CI 1.96-2.78) in major-risk patients, OR 1.13 (95% CI 0.90-1.41, not significant) in extreme-risk patients; similar for high-level exposure; no harmful effect observed in ventilated and non-ventilated ICU patients; adjusted number of patients needed to be exposed for one additional death 47.1 (95% CI 45.2-49.1)
• Funding: not stated.

Limit of this finding: This was a single-hospital, retrospective, observational study of 82,274 adults. It shows that patients who received chlorhexidine oral care were more likely to die, not that the rinse caused the deaths: sicker or differently treated patients may have been more likely to receive it, and the authors describe the result as an association. The same paper found no harmful effect in ICU patients, whether or not they were ventilated, so the signal applies to hospitalised patients outside intensive care.

Low-level exposure to chlorhexidine oral care (≤ 300 mg) was associated with increased risk of death [odds ratio (OR) 2.61; 95% confidence interval (CI) 2.32-2.92]. This association was stronger among patients with a lower risk of death: OR 5.50 (95% CI 4.51-6.71) with minor/moderate risk, OR 2.33 (95% CI 1.96-2.78) with a major risk, and a not significant OR 1.13 (95% CI 0.90-1.41) with an extreme risk of mortality. Similar observations were made for high-level exposure (> 300 mg). No harmful effect was observed in ventilated and non-ventilated ICU patients. Increased risk of death was observed in patients who did not receive mechanical ventilation and were not admitted to ICUs. The adjusted number of patients needed to be exposed to result in one additional fatality case was 47.1 (95% CI 45.2-49.1).

Chlorhexidine is a recognised and increasingly reported cause of perioperative anaphylaxis, and contact allergy is found in about 0.47-1% of patch-tested patients. (Source 6)

• Expert review, not systematic, Low certainty.
• Size: 252 reported anaphylaxis cases across 13 centres; 36 case-report articles reviewed.
• Who: Surgical and procedural patients exposed to chlorhexidine-containing products.
• How long: immediate (minutes to an hour after exposure)
• Result: Chlorhexidine was within the top four most commonly diagnosed causes of perioperative anaphylaxis in a 13-centre survey; patch-test contact-allergy prevalence 0.47-1%.
• Funding: not stated.

A recent survey from 13 centers reported 252 cases of anaphylaxis to chlorhexidine, and it was within the top four most commonly diagnosed causes of perioperative anaphylaxis along with neuromuscular blocking agents, antibiotics, and latex.16 The prevalence of chlorhexidine contact allergy by performing a patch test was 0.47–1% of patients.

Of 26 studies in a chlorhexidine bathing review, 16 described monitoring for adverse events and eight of those reported data, which were skin rashes, skin dryness and itching. (Source 7)

• Systematic review, Low certainty.
• Size: 8 of 26 included studies reported adverse-event data; 10 studies reported no patient-centred outcomes.
• Who: Hospital inpatients bathed with chlorhexidine.
• How long: varied by study.
• Result: Adverse events described qualitatively (skin rashes, skin dryness, pruritus); no pooled rate against comparator bathing.
• Funding: not stated.

The remaining 16 studies described monitoring of adverse events to CHG as reported by patients and/or from medical records. Of these 16, eight studies reported data on adverse events, such as skin rashes, skin dryness, and pruritus ²⁸,³¹,³²,³⁵,³⁸,⁴³,⁴⁶,⁴⁷.

What the evidence supports

Chlorhexidine mouthrinse added to normal tooth brushing produces a large reduction in dental plaque over 4 to 6 weeks. (Source 2)

• Systematic review, High certainty.
• Size: 950 participants across 12 trials.
• Who: Adults and adolescents using a mouthrinse as an adjunct to mechanical oral hygiene.
• How long: 4 to 6 weeks.
• Result: SMD 1.45 standard deviations lower plaque in the chlorhexidine group (95% CI 1.00 to 1.90), rated high-quality evidence.
• Funding: independent (Cochrane Oral Health)

Plaque was measured by different indices and the SMD at 4 to 6 weeks was 1.45 (95% CI 1.00 to 1.90) standard deviations lower in the chlorhexidine group (12 trials, 950 participants analysed, high-quality evidence), indicating a large reduction in plaque.

Chlorhexidine mouthrinse reduced gingivitis scores versus placebo or no rinse, but by a small amount on a 0 to 3 scale. (Source 2)

• Systematic review, High certainty.
• Size: 805 participants across 10 trials.
• Who: People with mild gingival inflammation (mean Gingival Index score 1 of 3)
• How long: 4 to 6 weeks.
• Result: Gingival Index reduced by 0.21 (95% CI 0.11 to 0.31) on a 0 to 3 scale.
• Funding: independent (Cochrane Oral Health)

After 4 to 6 weeks of use, chlorhexidine mouthrinse reduced gingivitis (Gingival Index (GI) 0 to 3 scale) by 0.21 (95% CI 0.11 to 0.31) compared to placebo, control or no mouthrinse (10 trials, 805 participants with mild gingival inflammation (mean score 1 on the GI scale) analysed, high-quality evidence).

Pooled across 26 studies, chlorhexidine bathing of inpatients was associated with a lower incidence of hospital-acquired bloodstream infection. (Source 3)

• Systematic review, Low certainty.
• Size: 26 studies, 861,546 patient-days, 5,259 hospital-acquired bloodstream infections.
• Who: ICU and non-ICU hospital inpatients.
• How long: varied by study.
• Result: IRR 0.59 (95% CI 0.52-0.68); absolute rates per patient-day not reported in the abstract read.
• Funding: not stated.

CHG bathing markedly reduced the risk of HABSIs (IRR = 0.59, 95% confidence interval [CI]: 0.52-0.68).

What the evidence does not support

The gingivitis reduction achieved with chlorhexidine mouthrinse in people with mild gum inflammation was judged by the review authors not to be clinically relevant. (Source 2)

• Systematic review, High certainty.
• Size: 805 participants across 10 trials (gingivitis comparison)
• Who: People with mild gingival inflammation on average.
• How long: 4 to 6 weeks.
• Result: 0.21 of one point on a 0 to 3 index; the review states this was not considered clinically relevant.
• Funding: independent (Cochrane Oral Health)

a reduction in gingivitis in individuals with mild gingival inflammation on average (mean score of 1 on the 0 to 3 GI scale) that was not considered to be clinically relevant

A systematic review of four studies (nine comparisons) found no significant difference in the plaque-inhibiting effect of chlorhexidine mouthwash when sodium lauryl sulphate toothpaste was used as a paste, but a significant difference when the toothpaste was used as a slurry rinse; the authors graded their recommendation as moderate because three of the four studies came from one research group. (Source 5)

• Systematic review, Low certainty.
• Size: four eligible publications with nine comparisons.
• Who: Adults (18 or older) in good general health in trials of chlorhexidine mouthwash with or without sodium lauryl sulphate dentifrice.
• How long: not stated in the abstract read.
• Result: Paste: no significant difference (MD 0.08; P = 0.42). Slurry rinse: significant difference in plaque inhibition (MD 0.33; P at or below 0.00001). Recommendation graded moderate because of potential publication bias.
• Funding: not stated.

Limit of this finding: The abstract is hard to read on one point: for toothpaste used as a slurry rinse it says the 'interference' with chlorhexidine's plaque-inhibiting effect was 'significantly decreased' (MD 0.33), while its conclusions treat the slurry result as a sign of interference, so the wording should not be taken to mean the slurry was harmless. The confidence interval printed for the paste result (-0.26 to 0.11) is not centred on the stated difference of 0.08, so those exact numbers should be treated with caution. The 'no interference' conclusion applies to toothpaste used as a normal paste, rests on four studies, and the authors grade it only moderate because three of the four came from the same research group.

The meta-analysis showed that when an SLS dentifrice was used as a slurry rinse, the interference on the plaque-inhibiting effect of a CHX mouthwash was significantly decreased (MD 0.33; P ≤ 0.00001; 95% CI: <0.24; 0.42>). No significant difference was observed when SLS dentifrice was applied as a paste in combination with CHX mouthwash (MD 0.08; P = 0.42; 95% CI: <-0.26; 0.11>).

Where the research disagrees

Whether chlorhexidine mouthrinse delivers a benefit that matters to the patient, as distinct from a measurable one

• Cochrane Oral Health review authors (James et al 2017), systematic review of 51 trials, high-quality evidence for the gingivitis and plaque outcomes: a reduction in gingivitis in individuals with mild gingival inflammation on average (mean score of 1 on the 0 to 3 GI scale) that was not considered to be clinically relevant (Source 2)
• US prescribing information for chlorhexidine gluconate 0.12% oral rinse, regulatory position citing microbiological sampling, not patient-centred outcomes: Chlorhexidine gluconate oral rinse provides antimicrobial activity during oral rinsing. The clinical significance of chlorhexidine gluconate oral rinse’s antimicrobial activities is not clear. Microbiological sampling of plaque has shown a general reduction of counts of certain assayed bacteria, both aerobic and anaerobic, ranging from 54–97% through six months use. (Source 1)

Whether toothpaste must be separated in time from a chlorhexidine rinse

• Elkerbout et al 2016 systematic review, systematic review of four studies, nine comparisons; no significant difference for toothpaste used as a paste, a significant difference for toothpaste used as a slurry rinse: No significant difference was observed when SLS dentifrice was applied as a paste in combination with CHX mouthwash (MD 0.08; P = 0.42; 95% CI: <-0.26; 0.11>). (Source 5)

How much

• Reference intake: Dosing is set by the prescriber or by the product label, not by the reader. As a position, the US prescribing information for chlorhexidine gluconate 0.12% oral rinse states a usual dose of 15 mL undiluted, rinsed twice daily for 30 seconds after brushing. (Source 1)
• Upper limit: No reference intake or tolerable upper intake level exists for chlorhexidine: it is a topical antiseptic drug, not a nutrient. The label's stated maximum is its dosing instruction of 15 mL twice daily; no higher ceiling is given. (Source 1)
• Studied: Trials pooled by Cochrane gave chlorhexidine mouthrinse as an adjunct to mechanical oral hygiene for 4 to 6 weeks and for 6 months; the review reports results by duration rather than by a single pooled concentration. (Source 2)
• Studied: Studies in the bathing review applied chlorhexidine gluconate as whole-body washes or impregnated cloths to hospital inpatients across 861,546 patient-days. (Source 3)

A common belief, and what the research shows

The belief: An antiseptic mouthwash that kills nearly all mouth bacteria must be good for your gums, and the brown staining is the only trade-off.

What the research shows: Plaque does fall a lot - Cochrane rates that high-quality evidence, with an SMD of 1.45 (95% CI 1.00 to 1.90). But in people with mild gum inflammation the gingivitis gain was 0.21 of a point on a 0 to 3 scale, and the review says it was 'not considered to be clinically relevant'. Staining is not the only harm either: taste disturbance was reported in 11 trials and mucosal soreness, desquamation or ulceration in 13, chlorhexidine is among the commoner identified causes of perioperative anaphylaxis, and a hospital-wide cohort linked routine chlorhexidine oral care to higher mortality (OR 2.61, 95% CI 2.32-2.92).

Questions and answers

What is it?

Chlorhexidine is a man-made antiseptic chemical, usually supplied as chlorhexidine gluconate. It is used on surfaces of the body - as a mouthrinse, a skin wash, impregnated wipes and surgical skin preparation - rather than swallowed as a systemic medicine. Very little of it crosses into the bloodstream, because it is poorly absorbed from the gut. (Source 1)

What does it do in the body?

It carries a positive charge, sticks to teeth, mucosa and bacterial surfaces, and suppresses the bacteria it touches, continuing to act between uses. In the mouth, the label reports that bacterial counts in plaque fell by 54-97% through six months of use, although it also states that the clinical significance of this antimicrobial activity is not clear. In trials it reduced dental plaque by a large margin compared with placebo or no rinse. (Source 1)

Is it good or bad for you?

It depends entirely on the setting. For plaque control alongside brushing, Cochrane rates the evidence high quality and the effect large. For gum inflammation in people whose gums are only mildly inflamed, the same review judged the improvement too small to be clinically relevant. Used routinely for mouth care in general hospital inpatients, a large cohort found it associated with higher mortality, so there it may do net harm. (Source 2)

How do you get more of it?

Does not apply in the nutrient sense: chlorhexidine is a drug, not something the body needs or stores, and there is no reason to seek more of it. How much a person is exposed to is set by whether a clinician prescribes it and by the product's own instructions - for the 0.12% oral rinse, the label's stated dose is 15 mL twice daily. This is recorded as the label's position, not as advice. (Source 1)

If it is harmful, what reduces it?

Because almost none of it is absorbed, stopping the product ends the exposure; nothing in the literature read describes a need to clear chlorhexidine from the body. Where harm is the concern, what is studied is stopping routine use rather than removing the drug: the hospital-wide cohort that linked chlorhexidine oral care to higher mortality concluded against indiscriminate use. Staining already on the teeth is removed by a dental professional, not by any antidote. (Source 4)

Why might someone be low in it or missing it?

Does not apply: nobody is deficient in chlorhexidine. A person has none in their body unless a product containing it has been used, and the only reasons to have less of it are not being prescribed it, stopping it, or having to avoid it because of allergy - which is a documented and increasingly reported problem. (Source 6)

Which whole foods contain it or feed it?

No whole food contains chlorhexidine; it is a synthetic antiseptic. The nearest food-related question in the literature read is what happens to swallowed traces, and the label states it is poorly absorbed from the gut. No study we found measured any food or drink changing its effect. (Source 1)

What happens if you do not have it?

Nothing happens from not having chlorhexidine - there is no deficiency state. What the evidence addresses is what is forgone: without it, plaque control rests on brushing and flossing alone, and Cochrane found that adding the rinse produced a large further reduction in plaque. For gingivitis in mildly inflamed gums the forgone benefit was judged not clinically relevant. (Source 2)

How can you test for it?

There is no blood or body test for chlorhexidine status, and none is needed. The testing that is actually described in the literature is allergy testing in people suspected of reacting to it: patch testing detects contact allergy, with a reported prevalence of 0.47-1% of patients tested, and allergy workup is used after suspected anaphylaxis. Those tests answer whether someone is sensitised, not how much chlorhexidine is in them. (Source 6)

References

1. DailyMed (US National Library of Medicine), SPL set ID b6b45b87-aa53-4d3a-be59-f3d3b0774a7b; label revised 09/2025. Chlorhexidine Gluconate Oral Rinse 0.12% - US prescribing information (labeler: Rising Pharma Holdings, Inc.), Clinical Pharmacology through Dosage and Administration sections. 2025. Read the source
2. Cochrane Database of Systematic Reviews (Cochrane Oral Health Group). Chlorhexidine mouthrinse as an adjunctive treatment for gingival health. 2017. PMID 28362061, DOI 10.1002/14651858.CD008676.pub2. Read the source
3. BMC Infectious Diseases. The impact of chlorhexidine bathing on hospital-acquired bloodstream infections: a systematic review and meta-analysis. 2019. PMID 31088521, DOI 10.1186/s12879-019-4002-7. Read the source
4. Intensive Care Medicine. Effects of chlorhexidine gluconate oral care on hospital mortality: a hospital-wide, observational cohort study. 2018. PMID 29744564, DOI 10.1007/s00134-018-5171-3. Read the source
5. International Journal of Dental Hygiene. Chlorhexidine mouthwash and sodium lauryl sulphate dentifrice: do they mix effectively or interfere?. 2016. PMID 25880828, DOI 10.1111/idh.12125. Read the source
6. Journal of Asthma and Allergy. Chlorhexidine Allergy: Current Challenges and Future Prospects. 2020. PMID 32210588, DOI 10.2147/JAA.S207980. Read the source
7. BMC Infectious Diseases (full text, Results section; Europe PMC PMC6518712). The impact of chlorhexidine bathing on hospital-acquired bloodstream infections: a systematic review and meta-analysis. 2019. PMID 31088521, DOI 10.1186/s12879-019-4002-7. Read the source