wound care

Pearls of Wisdom: Aphthous Ulcers

Question: Zeke is a 19-year-old college student with a history of recurrent aphthous ulcers. He has had 2 to 3 sores in his mouth since about age 13, and they usually last 5 to 7 days before spontaneously disappearing. He has tried over-the-counter teething remedies, and while they alleviate local symptoms, relief only lasts for a few hours, and most agents contain a topical anesthetic that rarely stays just on the site of the lesion, so his mouth and tongue get numb.

Zeke has no health problems, does not smoke, uses no recreational drugs, and does not drink alcohol. There is no family history of a similar disorder or Behçet syndrome. Zeke’s test results were negative for antibodies to herpes simplex virus (HSV) types 1 and 2.


Which of the following might be etiologic in recurrent canker sores?

A. Lymphoma
B. Celiac disease
C. Zinc deficiency
D. Sodium lauryl sulfate sensitivity

What is the correct answer?
(Answer and discussion on next page)

Louis Kuritzky, MD, has been involved in medical education since the 1970s. Drawing upon years of clinical experience, he has crafted each year for almost 3 decades a collection of items that are often underappreciated by clinicians, yet important for patients. These “Pearls of Wisdom” often highlight studies that may not have gotten traction within the clinical community and/or may have been overlooked since their time of publishing, but warrant a second look.

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Answer: Sodium lauryl sulfate sensitivity

Even though nobody dies from canker sores, they are a nuisance. The pathophysiology of canker sore development is not completely understood, but it is clear that they are not herpetic in origin as once thought. The dental community is much more familiar with aphthous stomatitis as a consequence of sodium lauryl sulfate (SLS) intolerance than is the primary care community.

What is SLS?

SLS is a standard ingredient in most toothpaste sold in the United States; its function is to make toothpaste foamy. This detergent-like action apparently is a sensation that many toothpaste users find positive. Unfortunately, in some SLS-sensitive persons, SLS may denature the mucin layer, which is protective of the buccal and gingival mucosa, leading to mucosal breakdown and aphthous ulcer formation.

SLS & Recurrent Aphthous Ulcer1

For example, in a small trial of persons (N= 10) with very frequent aphthous ulcer recurrences, during a 3-month cross-over interval ulcers were reduced more than 3-fold by switching SLS-free toothpaste instead of SLS-containing toothpaste.1

Study Results1

Many SLS-free toothpastes are marketed in the United States. To find such products, a simple web search will suffice.

The FDA had previously approved a prescription agent for aphthous stomatitis—Aphthasol (amlexanox, Uluru Inc.)—that was reported to have anti-inflammatory activity and was effective to treat recurrent canker sores. The drug has since been taken off the market in the United States but is still widely used in Japan.

What’s the “Take Home”?

Aphthous ulcers are an occasional nuisance to you and me, but for persons with highly recurrent disease, they can be a big nuisance. A switch from traditional toothpaste to SLS-free toothpaste might be just the right fix, and really, what do you have to lose?


  1. Herlofson BB, Barkvoll P. Sodium lauryl sulfate and recurrent aphthous ulcers. Acta Odontol Scand. 1994;52:257-259.