Can Toothpaste Trigger Canker Sores? What to Know

SLS is a surfactant commonly used in household soaps and detergents. It produces the bubbly, foamy sensation when you brush—something manufacturers promote because it creates a feeling of cleanliness.

Although that foamy sensation can feel reassuring, SLS can strip away the mouth’s natural protective lining. Repeated exposure may leave the underlying oral tissues irritated and more likely to develop aphthous ulcers (canker sores).

The Environmental Working Group rates SLS as a higher hazard for irritation and a moderate hazard for organ toxicity in its cosmetic ingredient database. It is a potent detergent; for perspective, highly concentrated SLS is even used in industrial cleaning solutions.

Clinically, dentists can often tell when patients use SLS-containing toothpaste by the characteristic sloughing of cheek cells visible during an exam. That appearance is one of the most recognizable signs of mucosal irritation caused by surfactants.

There’s no need to accept a harsh detergent in a product that should primarily help remove biofilm. Toothpaste’s core function is to act as a mild abrasive and polishing aid to assist the toothbrush in removing plaque. Many additional ingredients are marketing choices rather than necessary for effectiveness.

The oral mucosa is delicate and should not be repeatedly stripped or dried. Several studies have shown SLS can disrupt the protective mucin layer of the mouth, leaving tissues vulnerable to irritation and ulcers.

For that reason I advise patients—especially those prone to recurrent canker sores—to switch to an SLS-free toothpaste. Even if you rarely get canker sores, avoiding unnecessary irritation is a sensible precaution.

SLS-free toothpastes have become widely available and are now mainstream. You can find them at natural-food stores, major retailers, and many online sellers. As demand grows, manufacturers sometimes list SLS under alternative names, so it helps to know common synonyms used on ingredient lists.

Alternate names and related listings you may see include:

• 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
• Sodium salt
• A13-00356
• Akyposal SDS
• Aquarex Methyl

Switching to an SLS-free toothpaste is an easy, low-risk step that can reduce irritation. Many SLS-free formulations use alternative ingredients that protect the mucin layer while supporting enamel health and a balanced oral microbiome.

If recurrent canker sores are a problem for you, try a 30-day trial with an SLS-free toothpaste and monitor whether your symptoms improve. Check ingredient lists carefully, looking for the names above if you want to avoid SLS.

Practical steps:

• Try an SLS-free toothpaste for at least 30 days if you experience canker sores or oral irritation and note any changes.
• Read product ingredient lists for sodium lauryl sulfate or any of its alternative names.
• Consider toothpastes that focus on gentle cleaning and enamel support without harsh surfactants.

Choosing an SLS-free option removes an unnecessary irritant from your daily oral care routine. Whether you’re prone to mouth ulcers or simply want gentler care, plenty of effective SLS-free toothpastes are now readily available.

Dr. Mark Burhenne DDS

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