closeup of toothpaste on a toothbrush

Q. I used to have continuous terrible canker sores. I discovered that my toothpaste was the culprit. Since I brush my teeth daily, it was a never-ending cycle.

There is an ingredient in all the name brand toothpastes (sodium lauryl sulfate) that can cause problems for sensitive people. Switching brands made an immediate difference. I now buy my toothpaste at health food stores and almost never have canker sores anymore.

Others may want to try this approach, eliminating the problem rather than treating the symptoms. It can’t hurt and it might help.

A. Sodium lauryl sulfate (SLS) is a detergent found in toothpaste, shampoo, shaving cream, bubble bath and car wash soaps. Research on the effects of SLS on teeth and mouth is complicated and contradictory.

Some studies from the 1990s suggested that SLS might contribute to canker sores, while other trials showed no impact. More recently, SLS has been implicated in wear on tooth surfaces and irritation in the mouth (Swedish Dental Journal, Jan-March, 2003).

Some people may be more susceptible than others. Another reader offered this story:

“I used to have canker sores all the time and then I read about SLS in toothpaste. I searched around for toothpaste that did not contain this ingredient. I started using Biotene toothpaste and I have not had a canker sore since I started using this product. It also reduces dry mouth.”

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  1. Lubo

    I had canker sores for years and I noticed that it depended on the toothpaste that I used. When I read about the studies linking SLS and canker sores, I checked the ingredients and sure enough, when I used SLS-free toothpaste they would stop. The challenge has been finding SLS-free fluoride toothpaste, as a lot of brands are either offering fluoride with SLS or fluoride-free and SLS-free.

  2. Jeff Ohlsen

    I suffered from constant canker sores for 40 years. About 10 years ago, my doctor recommended using a “sensitive” type toothpaste for my sensitive teeth. I tried a couple of brands and eventually settled on Aquafresh Sensitive toothpaste. After using it for a while, I realized that I hardly every had canker sores anymore. I wasn’t sure what changed, but eventually, I realized that it must have been the toothpaste. I talked to my dentist and she explained that sodium lauryl sulfate can cause canker sores for some people. For the last few weeks, I noticed that I was getting canker sores again and I couldn’t understand why because I was still using the AquaFresh Sensitive toothpaste and the rest of my diet had not changed much. I finally decided to check the ingredients of my new tube of toothpaste and I discovered that it now contains sodium lauryl sulfate. Now, I have to throw several tubes away and look for a new brand of toothpaste that doesn’t contain sodium lauryl sulfate.

  3. Chip
    North Carolina

    I was getting recurring canker sores about 3 years ago and heard about the connection with SLS in toothpaste. I started using SLS-free toothpaste and have been free of canker sores ever since.

  4. Kevin H.

    I was getting mouth ulcers after drinking orange or grapefruit juices several days in a row. So I stopped drinking them and this “fixed” the problem. But I would still get the desire to drink them and get ulcers again. While I had an ulcer I went and got my teeth cleaned, I mentioned to my dentist about getting ulcers from citrus juices, he told me it was probably my toothpaste and to get a non-SLS tooth paste then try drinking citrus juices.

    So I did and it worked. So I now drink citrus juices eat oranges and don’t get ulcers. Happy Days!

  5. E J Hendricks

    Used to get severe canker sores and other mouth sores. Then I read about B12 sublingual vitamins. Found this from the Journal of the American Board of Family Medicine, that B12 soothed Recurrent Aphthous Stomatitis, “regardless of the Vitamin B12 serum level.” Works for me.

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