A lot of people have a nightly habit of rinsing with mouthwash. Some do it because it tastes good, others do it because they believe it helps with bad breath, while other do it because their dentist told them to. There are mixed opinions about the effectiveness of mouthwash, with some actually believing it can do you harm.
Mouthwash does, in fact, appear to be effective. One meta analysis found that mouthwash that contained the ingredient chlorhexidine (the current gold standard) reduced plaque by an average of 33% and gingivitis by an average of 26%. It has also been found to reduce bad breath. The downside of chlorhexidine mouthwash is that it has been found to stain teeth a light brown color at times. One study found that Listerine® and Meridol® (which don’t contain chlorhexidine) lowered plaque (but not as much as chlorhexidine) and had no effect on gingivitis. Another meta analysis, though, found that Listerine® was as effective as chlorhexidine in protecting against gingivitis.
Many mouthwashes contain alcohol, with some being composed of as much as 26% ethanol. Some studies have associated mouthwash containing alcohol with oral cancer. However, a meta analysis found no association between mouthwash use and cancer. Given that 5 recent studies have shown a negligible benefit to alcohol in terms of reducing plaque and gingivitis, you might want to go with a non-alcohol mouthwash to be safe.
Using mouthwash has been shown to be beneficial in reducing plaque, gingivitis and bad breath. So use a chlorhexidine mouthwash if want to reduce plaque and gingivitis as much as possible (and can stand the staining). If not, Listerine® appears to be a decent alternative. Go with a non-alcohol mouthwash regardless though.
Brecx, M., et al. “Efficacy of Listerine®, Meridol® and chlorhexidine mouthrinses on plaque, gingivitis and plaque bacteria vitality.” Journal of Clinical Periodontology 17.5 (1990): 292-297.
Gandini, Sara, et al. “Mouthwash and oral cancer risk quantitative meta-analysis of epidemiologic studies.” Annals of Agricultural and Environmental Medicine 19.2 (2012).
Herrera, David. “Chlorhexidine mouthwash reduces plaque and gingivitis.”Evidence-based dentistry 14.1 (2013): 17-18.
McCullough, M. J., and C. S. Farah. “The role of alcohol in oral carcinogenesis with particular reference to alcohol‐containing mouthwashes.” Australian dental journal 53.4 (2008): 302-305.
Neely, A. L. “Essential oil mouthwash (EOMW) may be equivalent to chlorhexidine (CHX) for long-term control of gingival inflammation but CHX appears to perform better than EOMW in plaque control.” The journal of evidence-based dental practice 12.3 Suppl (2012): 69-72.
Oliveira-Neto, Jeronimo M., Sandra Sato, and Vinícius Pedrazzi. “How to deal with morning bad breath: A randomized, crossover clinical trial.” Journal of Indian Society of Periodontology 17.6 (2013): 757.
Strydonck, Daniëlle AC, et al. “Effect of a chlorhexidine mouthrinse on plaque, gingival inflammation and staining in gingivitis patients: a systematic review.”Journal of clinical periodontology 39.11 (2012): 1042-1055.
Werner, CW de A., and R. A. Seymour. “Are alcohol containing mouthwashes safe?.” British dental journal 207.10 (2009): E19-E19.