Sodium Lauryl Sulfate, or SLS, is found in virtually every major brand of toothpaste. It is an effective and inexpensive detergent. Unfortunately, it has also been linked (in 4 of 5 independent clinical trials) to either significantly increase in number of canker sores, and or the duration and pain associated with canker sores when compared to brushing with SLS-free toothpaste. (Note: The only other common toothpaste ingredient found to indicate a slightly elevated canker sore risk is Cocoamidopropyl Betaine or CAPB. Verve toothpaste is also CAPB-free).

There have been five clinical trials that have looked at the relationship between canker sores and brushing with toothpaste containing Sodium Lauryl Sulfate ("SLS toothpaste"), versus using a toothpaste without Sodium Lauryl Sulfate ("SLS-free toothpaste"). In the briefest terms, the results of these trials, with regard to canker sore occurrences, pain, and duration are:

Trial 1) SLS toothpaste is bad. (preliminary study)

Trial 2) SLS toothpaste is bad and toothpaste containing CAPB is a little bit bad. (larger followup study)

Trial 3) SLS toothpaste is bad.

Trial 4) Inconclusive: while the study subjects fared better, on average, during SLS-free toothpaste periods than during the SLS-containing toothpaste periods, the effect was not as pronounced as in the other trials, and the statistical analysis of the results could not decisively rule out the possibility of a "chance" correlation. In the analysis of number of canker sores, the probability of a chance correlation was 6.6% (and therefore the probability of a real correlation was 93.4%). By convention, the probability of a chance correlation must be at or below 5% for the result to be considered statistically significant.

Trial 5) SLS toothpaste is bad.

In 2019 researchers did a systematic review of the studies above and used meta analysis to reach the following conclusion: SLS-free dentifrice (toothpaste), when compared to SLS-containing toothpaste statistically significantly, reduced the number of ulcers, duration of ulcer, number of episodes, and ulcer pain.

For references and a more detailed look at the research results, click here.
For articles on CANKER SORE PREVENTION, click here.
To visit our SLS-Free toothpaste home page, click here.