SLS in Toothpaste: What It Is and Why People Avoid It
If you've ever looked at a toothpaste ingredient list, you've probably seen "sodium lauryl sulfate" or "SLS" near the top. It's the ingredient responsible for the foaming action when you brush — and it's the single most common reason people switch to premium toothpaste.
But what actually is SLS, why does it cause problems for some people, and what are the alternatives?
What Is SLS?
Sodium lauryl sulfate (SLS) is a surfactant — a substance that reduces surface tension and creates foam. It's used in toothpaste for two reasons:
- Foaming — SLS creates the lather you feel when brushing, which helps distribute toothpaste around the mouth
- Emulsifying — SLS helps blend the oil-based and water-based ingredients in the toothpaste formula
SLS is also found in shampoo, body wash, dish soap, and many cleaning products. It's one of the most widely used surfactants in the world.
Why Do People Avoid SLS in Toothpaste?
1. Canker Sores (Aphthous Ulcers)
This is the most cited reason. Multiple studies have examined the relationship between SLS and canker sores. Research published in the Journal of Clinical Periodontology found that patients who switched to SLS-free toothpaste experienced a significant reduction in the number of canker sores.
SLS may cause this by stripping the protective mucin layer from oral tissue, making it more vulnerable to irritation and ulceration in susceptible individuals.
2. Mouth Irritation
Some people experience a burning or tingling sensation after brushing with SLS toothpaste. Others notice dry, peeling, or irritated inner lips, cheeks, or gums. This is particularly common in people with sensitive oral tissue.
3. Taste Alteration
Have you ever noticed that orange juice tastes terrible right after brushing? That's SLS. It temporarily suppresses sweet taste receptors and enhances bitter ones. While not harmful, it's an unnecessary side effect that SLS-free toothpastes avoid.
4. Ingredient Philosophy
Many people switching to natural or premium toothpaste simply prefer to avoid synthetic detergents in their oral care. If you're already choosing fluoride-free or vegan toothpaste, going SLS-free is a natural extension.
Does SLS-Free Toothpaste Still Clean?
Yes — and this is the biggest misconception about SLS-free toothpaste. Foaming does not equal cleaning.
The cleaning action in toothpaste comes from:
- Abrasives (hydrated silica, calcium carbonate) — these physically remove plaque and stains
- The mechanical action of your toothbrush — bristles disrupting plaque biofilm
- Active ingredients (fluoride, hydroxyapatite) — supporting enamel health
SLS contributes none of these. It only creates foam and helps distribute the paste. SLS-free toothpastes use milder alternatives that serve the same purpose without the irritation potential.
What SLS-Free Toothpaste Uses Instead
- Sodium lauroyl sarcosinate — a milder, plant-derived surfactant (don't confuse with SLS despite the similar name)
- Cocamidopropyl betaine — a gentle coconut-derived foaming agent
- No surfactant — some natural formulas skip foaming agents entirely, relying on abrasives and the brushing action alone
How to Know If Your Toothpaste Has SLS
Check the ingredient list for:
- "Sodium lauryl sulfate" or "SLS" — this is the ingredient to avoid
- "Sodium laureth sulfate" or "SLES" — a related but slightly milder surfactant, also avoided by some
Not the same thing: "Sodium lauroyl sarcosinate" looks similar but is a different, gentler ingredient. It's commonly used in SLS-free toothpastes and is generally well-tolerated.
Best SLS-Free Toothpastes in Australia
- Boka Ela Mint — n-Ha + xylitol, SLS-free, no artificial anything
- Davids Sensitive+Whitening — SLS-free, n-Ha, recyclable tube
- Keeko Dream Clean — Australian-made, coconut oil-based, SLS-free
- Gem Triple Whitening — Australian-made, enzyme whitening, SLS-free
- Grin Pro Enamel Care — affordable, SLS-free, available with or without fluoride
Browse our full SLS-free toothpaste collection — 145+ products from brands that never use SLS.
Should You Switch to SLS-Free?
Definitely switch if you experience:
- Recurring canker sores or mouth ulcers
- Burning, tingling, or irritation after brushing
- Dry, peeling inner lips or cheeks
- General oral tissue sensitivity
Consider switching if:
- You're already choosing natural or premium toothpaste
- You prefer to avoid synthetic detergents
- You want the gentlest possible formula
No need to switch if: You don't experience any irritation from your current toothpaste and are happy with the formula. SLS at toothpaste concentrations is not considered harmful for most people.
Related Reading
Frequently Asked Questions
Is SLS in toothpaste dangerous?
SLS is not considered dangerous at the concentrations used in toothpaste. However, it can cause irritation, canker sores, and discomfort in susceptible individuals. If you experience any of these symptoms, switching to SLS-free toothpaste is a simple solution. Most premium brands are SLS-free by default.
Does SLS cause canker sores?
Research suggests SLS may increase the frequency of canker sores in people who are already prone to them. A study in the Journal of Clinical Periodontology found a significant reduction in canker sore occurrence when patients switched to SLS-free toothpaste. If you get recurring canker sores, an SLS-free toothpaste is worth trying.
What is the difference between SLS and SLES?
SLS (sodium lauryl sulfate) and SLES (sodium laureth sulfate) are related surfactants. SLES goes through an additional processing step (ethoxylation) that makes it slightly milder. Both are avoided by people seeking SLS-free oral care. Most premium toothpaste brands avoid both.
Are all natural toothpastes SLS-free?
Not necessarily — some "natural" brands still use SLS. Always check the ingredient list. All toothpastes in our SLS-free collection have been verified to not contain sodium lauryl sulfate.
