Condition category
Infections and Infestations
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status

Plain English Summary

Background and study aims
COVID-19 is a condition caused by the coronavirus (called SARS-CoV-2) that was first identified in late 2019. This virus can infect the respiratory (breathing) system. Some people do not have symptoms but can carry the virus and pass it on to others. People who have developed the condition may develop a fever and/or a continuous cough among other symptoms. This can develop into pneumonia. Pneumonia is a chest infection where the small air pockets of the lungs, called alveoli, fill with liquid and make it more difficult to breathe.
In 2020, the virus has spread to many countries around the world and neither a vaccine against the virus or specific treatment for COVID-19 has yet been developed. As of April 2020, it is advised that people minimize travel and social contact, and regularly wash their hands to reduce the spread of the virus.
Groups who are at a higher risk from infection with the virus, and therefore of developing COVID-19, include people aged over 70 years, people who have long-term health conditions (such as asthma or diabetes), people who have a weakened immune system and people who are pregnant. People in these groups, and people who might come into contact with them, can reduce this risk by following the up-to-date advice to reduce the spread of the virus.
The aim of this study is to evaluate the effectiveness of commonly used commercial mouth-rinses (Betadine Gargle and Mouthwash, Pearlie white Chlor-rinse and Colgate Plax mouthwash) to reduce SARS-CoV-2 viral level in the saliva of COVID-19 positive patients. This study will provide evidence on the use of mouth rinses in reducing the viral load in the saliva of the COVID-19 patients and thereby help in reducing transmission of COVID-19.

Who can participate?
Patients with laboratory-confirmed diagnosis of COVID-19

What does the study involve?
Participants are randomly allocated to receive either Betadine Gargle and Mouthwash, Pearlie white Chlor-rinse, Colgate Plax mouthwash or water (control group). They are asked to provide saliva samples by spitting, then they are asked to rinse their mouth with mouth-rinse or water. Saliva samples are collected again at 5 minutes, 3 hours and 6 hours after using the mouth-rinse.

What are the possible benefits and risks of participating?
There is no known benefit to the participant. However, their participation may add to the medical knowledge about the effectiveness of mouthwashes against SARS-CoV-2, as well as the use of mouthwashes to reduce the spread of COVID-19 through saliva. There is no potential risk to participants from saliva collection methods as it is a non-invasive method.

Where is the study run from?
Singapore General Hospital (Singapore)

When is the study starting and how long is it expected to run for?
April 2020 to June 2021

Who is funding the study?
National Dental Center Singapore (Singapore)

Who is the main contact?
A/Prof C.J. Seneviratne

Trial website

Contact information



Primary contact

Dr Jaya Seneviratne


Contact details

5 Second Hospital Ave
+65 (0)65767141

Additional identifiers

EudraCT number

Nil known number

Nil known

Protocol/serial number


Study information

Scientific title

Evaluating the comparative efficacy of virucidal mouth-rinses in reducing SARS-CoV-2 viral load in saliva as a pre-procedural prophylactic strategy in healthcare settings


Study hypothesis

1. To comparatively evaluate the viral load of SARS CoV-2 in saliva before and 5 minutes after application of povidone-iodine (PI), chlorhexidine gluconate (CHX) and cetylpyridinium chloride (CPC) mouth-rinses in COVID-19 positive patients compared to water rinse.
2. To assess the duration of effectiveness of PVP-I, CHX and CPC mouthwashes in reducing the viral load of SARS-CoV-2 in COVID-19 positive patients at 3 h and 6 h time intervals compared to water rinse.

Ethics approval

Approved 17/06/2020, Centralised Institutional Review Board (168 Jalan Bukit Merah, #06-08 Tower 3 Connection One,
Singapore, 150168; +65 (0)6323 7515;, ref: 2020/2537

Study design

Single-centre interventional clinical trial

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use contact details to request a participant information sheet.


COVID-19 (SARS-CoV-2 infection)


The subjects are randomly allocated to three mouth-rinse groups, namely povidone-iodine (PI), chlorhexidine gluconate (CHX) and cetylpyridinium chloride (CPC) and water control group.
Allocation: using Robust Randomization App (RRApp) using block randomization technique
Masking: single-blind

Prior to saliva collection, patients are asked to refrain from eating, drinking, or performing oral hygiene procedures for at least 30 min. Three milliliters of saliva is collected by passive drool technique from all the enrolled COVID-19 patients at four timepoints. Firstly, a baseline saliva sample is collected prior to the intervention of the mouth-rinse. Immediately after this, patients are requested to rinse their mouth with the allocated mouth-rinse for 30 seconds. Commercial mouth-rinses are prepared at the dilution and dosage recommended by respective manufacturers. In brief, in the PI group 5 ml of PI mouthwash (commercially available as Betadine Gargle and Mouthwash 10 mg) diluted with 5 ml of water (0.5%) is used whereas in the CHX group, 15 mL of undiluted CHX mouthwash (commercially available as Pearly White Chlor-Rinse, 0.2% w/v) is used. In the CPC group and water control groups, 20 ml of 0.075% CPC (commercially available as Colgate Plax mouthwash) and 15 ml sterile water are used, respectively. Three milliliters of saliva is collected again from all subjects 5 minutes after the use of mouth-rinse. In order to evaluate the duration of the efficacy of mouth-rinses, salivary samples are collected at the 3 h and 6 h post-rinsing.

Intervention type



Drug names

Primary outcome measure

Salivary CT values of SARS CoV-2 measured using reverse-transcription polymerase chain reaction (RT-PCR) at baseline, 5 min, 3 h and 6 h

Secondary outcome measures

There are no secondary outcome measures

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

Laboratory-confirmed COVID-19-positive patients

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. History of allergy to PI, CPC or CHX and its relevant excipients
2. All forms of thyroid disease or current radioactive iodine treatment
3. Lithium therapy
4. Known pregnancy
5. Renal failure

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Singapore General Hospital
Outram Rd

Sponsor information


National Dental Centre of Singapore

Sponsor details

5 Second Hospital Ave
+65 (0)63275063

Sponsor type

Research organisation



Funder type

Research organisation

Funder name

National Dental Centre of Singapore

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

The protocol will be included in future publications. The results of the study will be published as soon as a reasonable conclusion is made from the study in a high-impact peer-reviewed journal.

IPD sharing statement
The datasets generated during and/or analysed during the current study are/will be available upon request from A/Prof.C.J. Seneviratne (

Intention to publish date


Participant level data

Available on request

Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes

08/09/2020: Trial's existence confirmed by Centralised Institutional Review Board (CIRB).