Sodium Lauryl Sulfate (SLS) in Toothpaste: Is It Good or Bad for Your Health? A Complete, Science-Backed Guide

Sodium lauryl sulfate (SLS) is one of the most debated ingredients in modern oral care. Some people swear it causes mouth sensitivity, ulcers, or irritation. Others insist it makes toothpaste more effective at cleaning and preventing plaque.

So… is SLS actually good or bad?
And if you avoid it, what’s the best substitute?

This guide breaks down what the science actually says — using findings from clinical trials, in-vitro studies, and recent literature reviews (2022–2024).

What Is Sodium Lauryl Sulfate (SLS)?

SLS is an anionic surfactant — a cleansing ingredient that reduces surface tension, dissolves oils, and creates foam. It’s the sodium salt of lauryl alcohol, used for more than 50 years in:

• Toothpaste
  
• Shampoos
  
• Soaps
  
• Detergents
  
• Pharmaceutical formulations
  

In toothpaste, SLS usually appears at 1–3% concentration.

It is NOT a carcinogen (confirmed by the International Agency for Research on Cancer).

Why SLS Is Used in Toothpaste (The Pros)

1. Better cleaning & foaming

SLS lowers the surface tension of water, helping toothpaste spread evenly across teeth and gums. This is what gives toothpaste its “foamy” feeling.

2. Antimicrobial effects

SLS can penetrate bacterial membranes — which helps reduce bacterial load on teeth and gums.

3. Increases available (free) fluoride

A study showed SLS significantly increases free fluoride in saliva, meaning:

• +147% increase in salivary fluid fluoride
  
• +205% increase in plaque fluid fluoride
  

Free fluoride is the form that actually protects enamel from decay.

If you want to know more about fluoride, check this article: What Is Fluoride and Why Is It in Toothpaste? And Fluoride Toothpaste and the Thyroid – What You Should Know

4. Helps plaque control

Studies show SLS can:

• Inhibit fructosyltransferase — an enzyme bacteria use to make sticky biofilm
  
• Reduce plaque accumulation in some cases
  
• Improve oral malodor (halitosis) by decreasing sulfur and ammonia gases
  

5. Improves drug solubility

In oral formulations, SLS enhances the solubility and bioavailability of poorly soluble drugs by forming micelles.

The Downsides of SLS (When It Can Be Bad)

Scientific evidence shows that SLS can cause irritation depending on concentration, exposure time, and individual sensitivity.

1. Oral irritation & mucosal shedding

SLS can temporarily disturb the oral epithelial barrier. Reported effects include:

• Peeling of oral mucosa
  
• Burning sensation
  
• Dryness
  
• Sensitivity
  
• Swelling
  

Oral mucosa is more sensitive to SLS than skin..

2. Worsening Recurrent Aphthous Stomatitis (Mouth Ulcers)

Multiple trials show SLS-free toothpaste leads to:

• Shorter healing time
  
• Lower pain levels
  
• Fewer ulcer episodes

If a patient has frequent ulcers, SLS-free toothpaste is strongly recommended.

3. Delayed wound healing

In vitro studies show SLS can slow epithelial repair.
After dental surgery, SLS may lengthen healing time.

4. Potential damage to the oral microbiome

Recent studies (2024) found SLS can:

• Disrupt oral biofilm diversity
  
• Increase certain pathogenic bacteria
  
• Cause gingival inflammation in animal models
  
• Promote alveolar bone resorption in rats
  

This does NOT happen in every person — but it’s an important emerging concern.

5. Cytotoxicity

Among common toothpaste ingredients, SLS showed the highest level of cytotoxicity on human gingival fibroblasts in one study.

6. Interference with enamel protection in early erosion

SLS can temporarily reduce the protective effect of sodium fluoride during initial erosion stages — though this does NOT persist in long-term erosion cycles.

So… Is SLS Good or Bad

It’s BOTH — depending on the person and situation.

✔️ SLS is beneficial if you:

• Do not have sensitive oral tissues
  
• Want stronger plaque and halitosis control
  
• Want maximized free fluoride availability
  
• Prefer high-foam toothpaste
  
• Have healthy gums without history of RAS
  

❌ SLS may be a problem if you:

• Frequently get mouth ulcers
  
• Have dry mouth (xerostomia)
  
• Have sensitive soft tissues
  
• Recently had oral surgery
  
• Have gingivitis or early periodontal inflammation
  
• Want a toothpaste that supports microbiome balance
  
• Experience peeling after brushing
  

The Best Substitutes for SLS (Gentler Surfactants)

Modern toothpaste brands are moving away from SLS because of irritation concerns. Here are the best alternatives:

1. Cocamidopropyl Betaine (CAPB)

• Milder than SLS
  
• Good foaming
  
• Less irritating
  

However, CAPB still has measurable cytotoxicity in vitro.

2. Sodium Lauroyl Sarcosinate

• Less irritating
  
• Effective foaming
  
• Better tolerated by sensitive mouths
  

3. Sodium Methyl Cocoyl Taurate

• Extremely gentle
  
• Good cleansing
  
• Suitable for ulcer-prone patients
  

4. PEG-based non-ionic surfactants (e.g., PEG-80 Sorbitan Laurate)

Very mild and commonly used in “sensitive” or “natural” formulas.

5. Postbiotic-based toothpaste (emerging category)

A 2024 study showed that postbiotic toothpaste can:

• Support a healthy oral microbiome
  
• Reduce inflammation
  
• Counteract the negative effects of SLS
  
• Prevent periodontal tissue damage
  

Postbiotics represent one of the most promising future alternatives.

What About “Natural” Toothpaste?

Natural toothpastes typically avoid:

• SLS
  
• Artificial sweeteners
  
• Preservatives
  
• Synthetic flavors and dyes
  

Instead, they rely on:

• Aloe vera
  
• Neem
  
• Calendula
  
• Tea tree oil
  
• Papaya leaf extract
  
• Chamomile
  
• Clove oil
  

These ingredients can provide anti-inflammatory or antibacterial benefits but may not always match the plaque-fighting effect of fluoride or SLS.

PICTURE OF toothpastes, last one.

This article will help you know more about the ingredients a toothpaste has.

Does Toothpaste Really Make a Difference?

Who Should Choose SLS-Free Toothpaste?

Based on current evidence, SLS-free dentifrices are recommended for:

⭐ People with recurrent mouth ulcers (RAS)

⭐ Patients after oral surgery

⭐ Individuals with mucosal sensitivity

⭐ People experiencing dryness or peeling

⭐ Those looking to support oral microbiome health

⭐ Patients with active gingivitis or periodontitis

⭐ Immunocompromised individuals (to avoid irritation)

For most other people, SLS is generally safe and effective in low concentrations.

Final Verdict

SLS is not harmful or carcinogenic, and it improves plaque control, fluoride availability, and overall cleansing.

However…

SLS can irritate oral tissues, slow wound healing, worsen ulcers, and disrupt the oral microbiome in certain individuals.

If you have a healthy, non-sensitive mouth → SLS is fine.

If you experience irritation or ulcers → choose an SLS-free or postbiotic-based toothpaste.

Consumers today have more options than ever — and the best formula depends on your oral biology, not just marketing.

REFERENCE

• Haghgoo R, Khorsand A, Ghaderi F, et al. The yin and yang of sodium lauryl sulfate use for oral and periodontal health: A literature review. Dent J (Basel). 2023;11(7):175.
• Promsudthi A, Boonroung T, Rojanapanthu P, et al. Chemical vs. natural toothpaste: Which formulas for which properties? A scoping review. Dent Med Probl. 2022;59(4):549–559.
• Wu Z, Li Y, Feng X, et al. Effects of sodium lauryl sulfate and postbiotic toothpaste on oral microecology. Arch Oral Biol. 2024;158:105833.
• Oshima S, Wilkins BJ, Singh G, et al. Detergent exposure induces epithelial barrier dysfunction and eosinophilic inflammation in the esophagus. Cell Mol Gastroenterol Hepatol. 2023;15(3):689–708.e5.