Background: COVID-19 has wreaked havoc on the world, causing millions of deaths and even more permanent health issues. Studies have examined various adjuvant treatments for this virus, with existing literature indicating that the use of mouthwashes and oral rinses can reduce viral load as well as improve clinical symptoms. However, there are many different types of mouthwash products available, with both in vivo and in vitro studies having been conducted. The aim of this review of the literature is to examine the use of various mouthwashes as an adjuvant treatment against the COVID-19 virus. Method: A database search of CINAHL, PubMed, Embase, and Web of Science databases was conducted using certain keywords and phrases, along with Boolean operators. The results were limited to those published between 2020 and 2023. Results: A total of 16 articles were identified which examined five primary molecules in mouthwashes: hydrogen peroxide, povidone-iodine, chlorhexidine, chlorine dioxide, and phthalocyanine derivate. Conclusion: There is good evidence to support the use of povidone-iodine, chlorhexidine, and phthalocyanine derivate as adjuvant treatments for COVID-19.