Substances that humans are regularly exposed to have the theoretical potential to cause harm, therefore it is appropriate that the use of mouth rinses – and other dental products – is examined from a safety perspective. This section will provide a discussion of potential health issues that have been raised about the use of alcohol-containing mouth rinses such as LISTERINE®, and the studies that have been conducted in this area.

More than thirty clinical studies, including long-term studies (6 months' duration) have been conducted on LISTERINE® over the last forty years. The original LISTERINE® has been available for more than 100 years. There is therefore a considerable body of data available that pertains to safety.

The safety evidence is based not only on historical data but also on clinical, epidemiological and laboratory investigations.
This section covers evidence of safety on oral hard and soft tissues, including:


LISTERINE® was originally formulated using ethanol (alcohol), which allows the essential oils to mix with the water base and acts as a preservative. Today, ethanol is a component of the LISTERINE® base range and the LISTERINE® Total Care mouth rinses. In both the base range and the Total Care range, LISTERINE® has ethanol-free variants (LISTERINE® Zero and LISTERINE® Total Care Zero respectively).


In the healthy state, saliva has a pH range of 6.7–7.4.1 A lower (more acidic) pH, below the critical value of 4.3–5, will favour demineralisation of the tooth, with (re)mineralisation occurring at higher pH levels.2


It has been suggested that long-term usage of mouth rinses with antiplaque and antigingivitis activity could possibly lead to an effect on the microflora, with an undesirable succession of opportunistic species occurring, or selection of species that develop resistance to the antimicrobial mouth rinse.1


The oral mucosa is a mechanical barrier that has selective permeability, allowing some substances to enter the body but which excludes others.1 There have been concerns raised over the effect of ethanol on the oral mucosa,2 potentially increasing permeability.3