Using Chlorhexidine Mouthwash to Crush the COVID-19 Curve

Chlorhexidine gluconate is an inexpensive and widely available mouthwash. We should make use of the existing evidence on Chlorhexidine and educate people to control the COVID-19 pandemic.

India is witnessing a new surge of cases, and scientists say COVID-19 second wave may peak in India by mid-April. It will take a long time to achieve herd immunity through vaccination, and factors like new variants and vaccine hesitation will prolong it further. Till then, we need an inexpensive and effective solution to control the pandemic.

A new study in the Journal of Medical Virology (March 2021) offers a great solution to this crisis. The study says that Chlorhexidine mouthwash can eradicate the virus from the oropharyngeal region.

To give you the background,

1. Chlorhexidine’s antiviral effect on enveloped viruses is known since the year 1990. The novel coronavirus SARS-COV-2 is an enveloped virus.

Ref: Bernstein D, Schiff G, Echler G, Prince A, Feller M, Briner W. In vitro virucidal effectiveness of a 0.12%-chlorhexidine gluconate mouthrinse. J Dent Res. 1990 Mar;69(3):874–6. doi: 10.1177/00220345900690030901. PMID: 2109001.

2. Lancet’s study in April 2020 showed that chlorhexidine could inactivate SARS-COV-2 in a concentration as low as 0.05%. Currently available mouthwashes of 0.2% w/v concentration are four times stronger than 0.05%.

Ref: Chin AWH, Chu JTS, Perera MRA, Hui KPY, Yen HL, Chan MCW, Peiris M, Poon LLM. Stability of SARS-CoV-2 in different environmental conditions. Lancet Microbe. 2020 May;1(1):e10. doi: 10.1016/S2666–5247(20)30003–3. Epub 2020 Apr 2. PMID: 32835322; PMCID: PMC7214863.

3. Another study (May 2020) showed that a single rinse with Chlorhexidine reduced the SARS-COV-2 viral load in the mouth for 2 hours, which can help reduce the viral transmission in the pandemic.

Ref: Yoon JG, Yoon J, Song JY, Yoon SY, Lim CS, Seong H, Noh JY, Cheong HJ, Kim WJ. Clinical Significance of a High SARS-CoV-2 Viral Load in the Saliva. J Korean Med Sci. 2020 May 25;35(20):e195. doi: 10.3346/jkms.2020.35.e195. PMID: 32449329; PMCID: PMC7246183.

4. An Indian study has found that Chlorhexidine digluconate in 0.2% concentration inactivated SARS CoV 2 in minimal contact time, i.e., 30 secs. With a much better efficacy than povidone-iodine.

Ref: Jain A, Grover V, Singh C, Sharma A, Das DK, Singh P, Thakur KG, Ringe RP. Chlorhexidine: An effective anticovid mouth rinse. J Indian Soc Periodontol. 2021 Jan-Feb;25(1):86–88. doi: 10.4103/jisp.jisp_824_20. Epub 2021 Jan 7. PMID: 33642749; PMCID: PMC7904017.

5. Taking it further, the latest study (March 2021) states that four days of chlorhexidine use can eliminate oropharyngeal SARS-COV-2 in Covid-19 patients.

This is of great significance when the cases are rising because chlorhexidine acts by destroying the outer envelope. So the mutations and genetically different variants are all susceptible.

Summary of the latest study (March 2021):

Use of chlorhexidine to eradicate oropharyngeal SARS‐CoV‐2 in COVID‐19 patients.

Ref: Huang YH, Huang JT. Use of chlorhexidine to eradicate oropharyngeal SARS-CoV-2 in COVID-19 patients. J Med Virol. 2021 Mar 23. doi: 10.1002/jmv.26954. Epub ahead of print. PMID: 33755218. Link: https://onlinelibrary.wiley.com/doi/full/10.1002/jmv.26954

Four days of chlorhexidine use eliminated SARS-COV-2 from the oropharynx in 62.1% of Chlorhexidine Mouthwash users (vs. 5.5% control) and 86.0% of Chlorhexidine mouthwash & oropharyngeal spray users (vs. 6.3% control).

Along with safe distancing, proper use of masks, hand sanitization, and eyewear, chlorhexidine can reduce virus transmission effectively.

The study says that chlorhexidine is a simple and safe addition to current COVID‐19 prevention guidelines and may significantly reduce disease spread.

Chlorhexidine compared to other mouthwashes:

One time acting chemicals like essential oils, alcohol, or povidone-iodine work well only outside the mouth. Inside the mouth, they are of no use for SARS-COV-2, as they inactivate the virus only for a limited amount of time (only so long as they are in the mouth). In the next 2 -3 minutes after spitting, the oropharyngeal region becomes filled with the virus again, coming from salivary glands and lungs.

To reduce the viral load and minimize the SARS-CoV-2 transmission, you need sustained action from a mouthwash. For a mouthwash to exert sustained action, it should have substantivity. The only molecule that has substantivity is Chlorhexidine.

Ref: Eley, B. Antibacterial agents in the control of supragingival plaque — a review. Br Dent J 186, 286–296 (1999). https://doi.org/10.1038/sj.bdj.4800090

The problem with the earlier studies:

All previous in vitro studies had used 0.02 percent Chlorhexidine which is meaningless as all current Chlorhexidine mouthwashes are 6 to 10 times more concentrated than 0.02 percent.

Lancet's study (April 2020) showed that Chlorhexidine could inactivate SARS-COV-2 in a concentration as low as 0.05 percent. (in-vitro)

We need to make use of what works rather than what does not. Therefore, we should make use of 0.05 percent Chlorhexidine rather than 0.02 percent.

Coming to the commercially available Chlorhexidine formulations, the commonly available 0.2 percent Chlorhexidine is four times stronger than 0.05 percent, which is the minimum concentration required to inactivate SARS-COV-2, and ten times stronger than the earlier tested 0.02 percent.

How to make the best use of the substantivity of Chlorhexidine?

A study published in the year 2010 showed that

1. Increasing the volume of 0.12 or 0.2 percent Chlorhexidine mouthwashes does not affect the duration of antimicrobial activity in saliva.
2. Increasing the duration produces a marked increase in substantivity.
3. Substantivity was greater with 0.2 percent than 0.12 percent Chlorhexidine.
4. Eating, chewing, or drinking significantly reduces the 0.2 percent Chlorhexidine substantivity in saliva.

Ref: Tomás I, Cousido MC, García-Caballero L, Rubido S, Limeres J, Diz P. Substantivity of a single chlorhexidine mouthwash on salivary flora: influence of intrinsic and extrinsic factors. J Dent. 2010 Jul;38(7):541–6. doi: 10.1016/j.jdent.2010.03.012. Epub 2010 Apr 7. PMID: 20380865.

We should make use of these newer lines of evidence and educate the people and help them make use of Chlorhexidine mouthwash to rinse the mouth and gargle the throat to eliminate the virus and reduce the transmission of the virus. Chlorhexidine gluconate is an inexpensive and widely available mouthwash. This way, they will reduce their viral load and reduce the transmission, thus help control the pandemic crisis.