Sodium lauryl sulfate (SLS) is a common chemical found in countless personal care products, including the majority of commercial toothpastes. It functions as an anionic surfactant, an ingredient that lowers surface tension to allow for better spreading and mixing of a product’s components. While consumers have increasingly expressed anxiety about its inclusion in oral care, SLS is primarily included in toothpaste for functional purposes. The debate surrounding its safety centers on the difference between localized irritation in the mouth and the more serious, but unproven, risks of long-term systemic toxicity.
Why Is Sodium Lauryl Sulfate in Toothpaste?
SLS is incorporated into toothpaste formulations primarily as a detergent and foaming agent. Its surfactant properties allow it to efficiently break down the surface tension between the paste ingredients and the plaque or debris in the mouth. This action helps to lift and remove food particles and oily substances from the tooth surface, contributing to the overall cleaning process.
The most noticeable effect of SLS is the generation of foam or lather when brushing, even though the concentration used in toothpaste is relatively low, typically ranging from 0.5% to 2.5% by weight. This foaming action is not strictly necessary for the physical cleaning of the teeth, but it serves a practical purpose by helping to distribute the active ingredients, such as fluoride, evenly across all oral surfaces. For many consumers, the rich lather also provides a sensory cue, giving a psychological perception of a more thorough and effective clean.
Localized Side Effects and Oral Irritation
The main concern regarding SLS is its potential to cause localized irritation within the oral cavity. As a strong detergent, SLS can disrupt the delicate balance of the oral mucosa, the moist lining inside the mouth. This disruption can manifest as symptoms like a burning sensation, dryness, or peeling of the inner cheek lining.
For individuals prone to developing mouth ulcers, specifically recurrent aphthous stomatitis (canker sores), the presence of SLS may be problematic. Studies show a strong correlation between using SLS-containing toothpaste and an increase in the frequency, duration, and pain intensity of these lesions. The mechanism involves SLS stripping away the protective layer of mucin, a protein that forms a barrier on the oral tissues.
When this protective mucin layer is compromised, the underlying mucosal tissues become more exposed and vulnerable to irritants and minor trauma, triggering the formation of an aphthous ulcer. People with a history of recurrent canker sores often experience a significant reduction in outbreaks after switching to an SLS-free dentifrice. This localized effect highlights that while SLS is generally tolerated, it acts as a known irritant for sensitive individuals.
Addressing Major Systemic Health Concerns
Despite concerns about localized irritation, the severe systemic health fears often associated with SLS, such as links to cancer or long-term toxicity, are not supported by current scientific evidence. Major regulatory bodies worldwide have reviewed the safety profile of SLS and consider it safe for use in consumer products at the concentrations found in toothpaste.
SLS is not classified as a carcinogen, and there is no evidence suggesting it causes genetic damage or endocrine disruption when used in oral care. When brushing, the toothpaste is in contact with oral tissues only for a short period before being rinsed, which limits the potential for significant systemic absorption. Scientific consensus focuses on potential adverse effects being limited to the surface tissues of the mouth, not internal organs or long-term systemic health.
Finding SLS-Free Toothpaste Options
For individuals experiencing persistent oral irritation, dryness, or recurrent canker sores, switching to an SLS-free toothpaste is a practical solution. Consumers should check the ingredient label for the presence of SLS, which is sometimes listed as sodium dodecyl sulfate.
Manufacturers often replace SLS with milder surfactants to maintain a pleasant mouthfeel and some degree of foaming. Common alternatives include cocamidopropyl betaine (CAPB) or sarcosinates, which function as gentler foaming agents.
These alternative formulations are just as effective at removing plaque and cleaning the teeth as their SLS-containing counterparts, since the mechanical action of the toothbrush is the primary cleaning factor. While these SLS-free options may produce less lather, they provide a gentler experience for sensitive oral tissues without compromising the benefits of ingredients like fluoride.