The COVID-19 pandemic sparked interest in various protective measures, including common oral hygiene products. Many wondered if mouthwash, a daily staple, could defend against the SARS-CoV-2 virus. While mouthwash freshens breath and promotes oral cleanliness, its relevance to the virus responsible for COVID-19 warrants a closer look at the scientific evidence.
How Mouthwash Ingredients May Affect Viruses
Mouthwashes contain active ingredients with antiseptic or antimicrobial properties that can impact viruses. Cetylpyridinium chloride (CPC) is a compound that disrupts the outer lipid membrane of enveloped viruses like SARS-CoV-2, inactivating them. Povidone-iodine (PVP-I) releases free iodine, which penetrates microbial structures and interferes with proteins and nucleic acids. Hydrogen peroxide (HP) acts as an oxidizing agent, damaging viral structures and potentially locking the SARS-CoV-2 spike protein in a non-functional state. Some mouthwashes also incorporate essential oils like thymol, eucalyptol, menthol, and eugenol, known for their antimicrobial properties against various microbes, including some viruses.
Current Research on Mouthwash and COVID-19
Laboratory studies (in vitro studies) have explored how certain mouthwash formulations inactivate SARS-CoV-2. These studies show that mouthwashes with ingredients like cetylpyridinium chloride (CPC) and povidone-iodine (PVP-I) can reduce SARS-CoV-2 viral load in saliva samples. For example, CPC at 0.05% has reduced SARS-CoV-2 infectivity within 60 seconds. PVP-I solutions at 0.23% have inactivated SARS-CoV-2 in as little as 15 seconds.
These studies primarily focus on reducing detectable virus in the oral cavity. While promising, human clinical trials have largely focused on temporary reductions in salivary viral load, not preventing infection or treating the disease. Some trials observed temporary reductions, particularly within 30 minutes of rinsing, with ingredients like chlorhexidine (CHX), PVP-I, and hydrogen peroxide. For instance, CPC mouthwashes reduced salivary SARS-CoV-2 levels within 5 minutes, with effects potentially lasting up to 6 hours.
Understanding the Limitations
Despite promising laboratory findings, mouthwash is not a cure, treatment, or primary preventive measure for COVID-19. Its effects are temporary and localized to the mouth and throat, not impacting the virus once it reaches the respiratory tract or lungs. Even with temporary viral load reduction in the mouth, the virus can still reside and replicate in nasal passages, potentially reintroducing it to the throat.
Mouthwash does not prevent infection or transmission through airborne respiratory droplets from the lungs, a primary mode of SARS-CoV-2 spread. Therefore, relying on mouthwash as a standalone defense against COVID-19 is not supported by current evidence. It should not replace established public health measures like vaccination, mask-wearing, physical distancing, and consistent hand hygiene, which remain foundational strategies.
Official Health Guidance
Leading health organizations, including the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO), do not recommend mouthwash as a primary tool for preventing or treating COVID-19. Some dental associations initially suggested pre-procedural mouth rinses in dental settings to reduce microorganisms, but noted a lack of specific clinical evidence for SARS-CoV-2 transmission prevention. While research continues to explore mouthwash’s potential role, current official guidance emphasizes adherence to proven public health measures.