When toothpaste foams in the mouth, one substance is usually responsible: sodium lauryl sulfate, or SLS for short. For most people, this is completely unproblematic. For some, however, switching to an SLS-free toothpaste is noticeably worthwhile.
What SLS does in toothpaste
SLS is a surfactant, a detergent substance also found in shampoo and shower gel. In toothpaste, it has three tasks: it distributes the paste in the mouth, helps loosen plaque and food debris, and provides the foam that many associate with "clean."
By the way, the foam itself doesn't clean. It is primarily a sensation.
Why SLS is controversial
Aphthae
The best-studied point is aphthae, the small, painful blisters and ulcers on the oral mucosa. SLS can attack the protective layer of the mucosa. A systematic review from 2019 concluded that people with recurrent aphthae tended to have fewer and shorter episodes and less pain with SLS-free toothpaste. The underlying studies were small, but the connection is plausible and worth a try for those affected.
Sensitive oral mucosa
Anyone prone to burning, redness, or a rough feeling on their cheeks and tongue sometimes reacts to SLS. Here, too, the rule applies: not everyone, but some significantly.
Dry mouth
With dry mouth, the saliva film that normally protects the mucosa is missing. Surfactants can then increase the feeling of dryness. More on this in the article Dry mouth: what to do?
The orange juice effect
Almost everyone knows this: after brushing your teeth, orange juice tastes bitter. SLS is partly responsible for this as well, because it temporarily alters the perception of taste. Harmless, but a nice example of the fact that the substance in the mouth is not entirely passive.
For whom an SLS-free toothpaste is useful
- For recurrent aphthae. Switching is the most obvious measure here.
- For sensitive or irritated oral mucosa.
- For dry mouth, for example due to medication or during menopause.
- If you want to specifically reduce ingredients that have no care benefit that could not be achieved in another way.
And honestly: those who don't have these complaints don't have to switch. SLS is approved in toothpaste and well tolerated by most people.
SLS-free does not mean surfactant-free
This is often overlooked. Even toothpastes without SLS usually require a surfactant to distribute and loosen plaque. Instead of SLS, milder or differently structured substances are used, for example:
- Cocamidopropyl Betaine
- Glucosides such as Decyl Glucoside
- Sodium Methyl Cocoyl Taurate
- Sodium C14-16 Olefin Sulfonate
Those who react to SLS often get along well with these alternatives. Those who are sensitive to surfactants in general must try out which formula fits.
How to recognize SLS on the tube
Look for Sodium Lauryl Sulfate in the list of ingredients. Two mix-ups occur frequently:
- Sodium Laureth Sulfate (SLES) is a different, chemically modified substance considered milder. It is not the same as SLS, but it is also not SLS-free in the sense of surfactant-free.
- Sodium Lauroyl Sarcosinate sounds similar, but is also a different surfactant.
Does an SLS-free toothpaste foam?
Less. This is unfamiliar at the beginning, but says nothing about the cleaning performance. Decisive for clean teeth are brushing technique, time, interdental spaces, and the right active ingredients. A good brush like the MINT Clean toothbrush and daily interdental care with MINTFloss dental floss make more of a difference than any foam. Many notice after a few days that they even brush more thoroughly with less foam because they don't have the feeling of being done as quickly.
The MINT toothpastes
All MINT toothpastes are free of SLS. Instead of SLS, Sodium C14-16 Olefin Sulfonate is used. They also avoid titanium dioxide; why this is useful can be found in Titanium dioxide in toothpaste.
For sensitive oral mucosa and sensitive teeth, MINT Sensitive toothpaste is suitable, for irritated gums MINT Paro+ toothpaste, and for the oral flora the MINT Biotic toothpaste.
More on ingredients that have no business in toothpaste can be found in the article Toothpaste No-Gos.
Frequently asked questions about SLS-free toothpaste
What does SLS mean in toothpaste?
SLS stands for Sodium Lauryl Sulfate. It is a surfactant that distributes the toothpaste, loosens plaque, and provides foam.
Is SLS in toothpaste harmful?
Not for most people. SLS is approved and well tolerated. However, with recurrent aphthae, sensitive mucosa, or dry mouth, it can exacerbate complaints.
Does SLS-free toothpaste help against aphthae?
It can help. Studies suggest that people with recurrent aphthae have fewer and shorter episodes with SLS-free toothpaste. A trial of a few weeks is worthwhile.
Does SLS-free toothpaste foam?
Less than usual. But the foam does not indicate how well the toothpaste cleans.
Is SLES the same as SLS?
No. Sodium Laureth Sulfate is a chemically modified, milder substance. It is not SLS, but it is also a surfactant.
Professional background: MINT Cosmetics was founded by Dr. Mariana Mintcheva, a dentist specializing in aesthetic dentistry and head of the MINT Dental Spa in Düsseldorf. All guide content is based on practical dental experience. It does not replace individual dental advice.
