Canker sores, medically known as aphthous ulcers, are common, painful, shallow lesions that develop on the soft tissues inside the mouth or at the base of the gums. These ulcers typically appear white or yellowish with a distinct red border. While the precise causes of canker sores can be intricate and vary among individuals, many people have observed a connection between their occurrence and the use of products containing sodium lauryl sulfate (SLS). This connection has led to questions about how this common ingredient might contribute to oral discomfort.
Understanding Sodium Lauryl Sulfate
Sodium lauryl sulfate (SLS) is a chemical compound widely used as a surfactant in various personal care products. A surfactant reduces the surface tension between liquids, or between a liquid and a solid, allowing for easier mixing and spreading. This property makes SLS effective as a cleansing and foaming agent. In products like toothpaste, shampoos, body washes, and soaps, SLS is primarily included to create a rich lather and foam, which many consumers associate with effective cleaning. SLS is valued in the manufacturing industry due to its effectiveness and relatively low cost.
How SLS Irritates Oral Tissues
As a strong detergent, SLS can interact with the delicate lining of the mouth, known as the oral mucosa. One primary mechanism of irritation involves its detergent properties, which can strip away the protective mucin layer and lipids from the oral tissues. This removal of the natural barrier makes the mouth’s lining more vulnerable to external irritants, physical trauma, and other factors that might trigger the formation of canker sores. SLS can also denature proteins within the oral tissues, leading to cellular damage and increasing the permeability of the mucosal barrier. This denaturation process can compromise the integrity of oral cells, making them more susceptible to irritation and inflammation. For some individuals, SLS acts as a direct irritant, causing localized inflammation and tissue breakdown that can precede the development of canker sores. Research indicates that individuals who switch to SLS-free toothpastes often report a reduction in the frequency or severity of their canker sores. This suggests a link between SLS exposure and canker sore occurrences for sensitive individuals. Not everyone reacts to SLS in the same way, as sensitivity levels vary significantly among people.
Identifying and Avoiding SLS
For individuals who suspect a connection between SLS and their canker sores, reducing exposure to this ingredient in oral care products can be beneficial. Checking product labels is the primary way to identify SLS, which is typically listed as “sodium lauryl sulfate” or “sodium dodecyl sulfate.” It may also appear as “sulfuric acid, monododecyl ester, sodium salt,” or “aquarex me” and “aquarex methyl.” SLS is a common ingredient in many oral care items, including most toothpastes and some mouthwashes. To avoid it, consumers can look for products explicitly labeled “SLS-free.” Many alternative products use gentler foaming agents derived from natural sources. These include ingredients such as sodium cocoyl glutamate, sodium lauroyl sarcosinate, or cocamidopropyl betaine. Observing the impact of switching to SLS-free products on canker sore frequency and severity can help determine if SLS is a contributing factor for an individual.