Do Certain Toothpastes Cause Canker Sores?

Many toothpastes contain an ingredient called Sodium Lauryl Sulfate (SLS). SLS is a strong detergent and has demonstrated in several studies to increase canker sore outbreaks and pain.

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Hi, I’m Dr. B, practicing functional dentist for 35 years. I graduated from the Dugoni School of Dentistry in San Francisco, CA in 1987 and am a member of the American Academy of Dental Sleep Medicine (AADSM), Academy of General Dentistry (Chicago, IL), American Academy for Oral Systemic Health (AAOSH), and Dental Board of California. I'm on a mission to empower people everywhere with the same evidence-based, easy-to-understand dental health advice that my patients get. Learn more about Dr. B

Q: Dr. Burhenne, I’ve heard that certain toothpastes can cause canker sores. Is this true?

A: Many toothpastes contain an ingredient called Sodium Lauryl Sulfate (SLS). SLS is a strong detergent and has demonstrated in several studies to increase canker sore outbreaks and pain.

SLS is a surfactant and a foaming agent found in most household soaps and detergents. It gives you that bubbly, foamy feeling when you’re brushing that manufacturers know make you feel like your mouth is cleaner.

That foamy feeling from SLS might feel good, but SLS actually strips away the protective lining of the mouth.

SLS is rated as high hazard for irritation and a moderate hazard for organ toxicity by EWG’s Cosmetic Database. It’s strong stuff — the cleaning solution I use on our garage floor is 50% SLS.

I can tell when my patients are using a toothpaste with SLS in it because of the sloughing of cheek cells on my intraoral mirror. It’s one of the most recognizable conditions in the mouth.

But there’s no reason to accept a hazardous chemical in your toothpaste.

All toothpaste needs to be to do the job is to be a mild polishing or abrasive agent that assists the toothbrush in removing biofilm. Anything beyond this is not part of the efficacy of the toothpaste — rather, a marketing battle for shelf space.

The mouth is a sensitive area that you never want to strip clean or dry out. Several studies showed that SLS breaks down the protective lining of the mouth, leaving the underlying tissues irritated and prone to break out in canker sores.

I recommend to all my patients and readers — whether they’re prone to canker sores or not — to use an SLS-free toothpaste.

SLS-free toothpastes have caught on and are now becoming mainstream. You’ll find them at Whole Foods, Amazon, and even Safeway or Walgreens — [Pinterest board.]

Beware that manufacturers are also hiding SLS in their ingredients under different names, as SLS-free toothpaste becomes more popular (from the EWG Cosmetics Database):

  • Monododecyl ester sodium salt sulfuric acid
  • Sodium Dodecyl sulfate
  • Sodium dodecyl sulphate
  • Sodium salt sulfuric acid
  • Monododecyl ester
  • Sulfuric acid monododecyl ester sodium salt
  • Sulfuric acid
  • Monododecyl ester
  • Sodium salt
  • A13-00356
  • Akyposal SDS
  • Aquarex Methyl

I recommend that all my patients switch to an SLS-free toothpaste, especially those suffering from frequent canker sores.

What to do:

  • If you suffer from canker sores, allergic reactions in the mouth, or other types of irritation, try switching to an SLS-free toothpaste for 30 days and track your results to see if there’s an improvement.
  • Check if your toothpaste has SLS, check this database:
  • Check out my Pinterest board of my favorite SLS-free toothpastes, all taste-tested and approved by me

Don’t become a part of this battle for shelf space when making decisions for a product that can impact your good health. Whether you’re prone to canker sores or not, SLS is an unnecessary hazardous chemical and SLS-free options abound.

Dr. Mark Burhenne DDS

Learn More: Cold Sores vs. Canker Sores: Why You Should Know the Difference