Several common toothpaste ingredients have enough evidence against them to warrant a closer look at your tube’s label. Some irritate the soft tissue inside your mouth, others carry endocrine-disruption concerns, and a few can physically damage your enamel over time. The six ingredients worth avoiding span foaming agents, preservatives, antimicrobials, abrasives, and even tiny plastic particles, and in most cases, effective alternatives already exist on store shelves.
Sodium Lauryl Sulfate
Sodium lauryl sulfate, usually listed as SLS, is the detergent responsible for the foamy lather most people associate with brushing. It shows up in the majority of mainstream toothpastes because it spreads the paste around your mouth efficiently and gives a “clean” sensation. The problem is that SLS is also a well-documented mucosa irritant. A clinical study comparing SLS-containing toothpaste to a formulation using a milder surfactant found that tissue sloughing, the peeling of the soft lining inside your cheeks, was roughly four times more likely after using the SLS product.1ScienceDirect / Journal of Dentistry. A randomised clinical study comparing the effect of Steareth 30 and SLS containing toothpastes on oral epithelial integrity (desquamation) SLS disrupts the protective salivary layer that coats the inside of your mouth, which leaves the tissue underneath more exposed.
If you get canker sores (recurrent aphthous ulcers), the evidence is even more pointed. A systematic review pooling data from multiple trials found that switching to an SLS-free toothpaste significantly reduced the number of ulcers, how long each ulcer lasted, the number of flare-ups, and the pain reported by patients.2PubMed. Effect of sodium lauryl sulfate on recurrent aphthous stomatitis: A systematic review That is a consistent improvement across all four measures researchers tracked. If canker sores are a recurring problem for you, dropping SLS is one of the simplest changes to try.
Milder surfactants like cocamidopropyl betaine (CAPB) can replace SLS without the same level of irritation. Research on betaine-based alternatives has shown they still clean effectively while producing significantly less mucosal irritation than SLS.3PubMed. Betaine reduces the irritating effect of sodium lauryl sulfate on human oral mucosa in vivo You will get less foam, which brings up a separate misconception covered later in this article, but your teeth will be just as clean.
Triclosan
Triclosan is a synthetic antimicrobial that became ubiquitous in personal-care products during the 1990s and 2000s. The FDA banned it from consumer hand and body soaps in 2016, concluding that manufacturers had not demonstrated it was safe for long-term daily use or more effective than plain soap and water. Despite that ban, triclosan remains legal in other products, and some toothpaste formulations still contain it at relatively high concentrations.4PubMed Central. Triclosan exposure, transformation, and human health effects
The core concern with triclosan is endocrine disruption. It is readily absorbed through the oral mucosa and skin, and once inside the body it can interfere with estrogen and androgen receptors, disrupt thyroid hormone regulation, and alter the activity of aromatase, an enzyme involved in sex-hormone production. Animal research has linked prolonged triclosan exposure to oxidative stress in reproductive tissues, and because triclosan is lipophilic, meaning it accumulates in fatty tissue, the risks compound with extended daily use.5UTTAR PRADESH JOURNAL OF ZOOLOGY. The Effect of Triclosan in Endocrine and Reproductive Disruption: A Comprehensive Review Most of this evidence comes from animal models rather than human trials, so the exact relevance to humans at toothpaste-level doses is still debated. But the FDA’s decision to pull it from soaps and the growing body of literature on endocrine effects give plenty of reason to choose a triclosan-free toothpaste, especially since alternatives exist.
One argument occasionally raised in triclosan’s favor is that it helps fight plaque and gingivitis. A long-term study spanning 19 years of continuous triclosan toothpaste use did confirm that it does not promote bacterial resistance in the mouth, which is reassuring from an antibiotic-stewardship standpoint.6PubMed. Long-Term Use of Triclosan in Dentifrice Does Not Develop Oral Bacterial Resistance for Patients with Periodontal Disease But “does not cause resistance” is a different claim from “is worth the endocrine risk.” Fluoride toothpaste with stannous fluoride or cetylpyridinium chloride offers anti-gingivitis benefits without triclosan’s baggage.
Diethanolamine
Diethanolamine, abbreviated DEA, is used in some toothpastes and cosmetics as a foaming agent or pH adjuster. On its own, DEA is not considered especially dangerous. The problem arises when DEA reacts with other ingredients, particularly nitrites and nitrosating agents that can be present in the same formulation. That reaction produces N-nitrosodiethanolamine (NDELA), a nitrosamine classified as a probable human carcinogen. A risk assessment of nitrosamines in cosmetic products found that higher nitrite concentrations and more nitrosating agents in a formula increased the yield of NDELA and its close relative NDEA, and that the presence of DEA itself significantly influenced how much of these nitrosamines formed.7PubMed. Risk assessment of N-nitrosodiethylamine (NDEA) and N-nitrosodiethanolamine (NDELA) in cosmetics
The researchers concluded that both DEA and related amines should be minimized in cosmetics to levels as low as technically feasible. Some regulatory bodies in Europe have already restricted DEA concentrations in personal-care products. For toothpaste specifically, the exposure is relatively brief compared to a leave-on cream, but since DEA serves a function that other ingredients can fulfill without the nitrosamine risk, there is no strong reason to accept even a small hazard. When reading labels, also watch for triethanolamine (TEA), which carries the same nitrosamine-forming potential.
Parabens
Parabens, including methylparaben, ethylparaben, and propylparaben, are preservatives added to prevent microbial growth in toothpastes, cosmetics, and pharmaceuticals. They are effective at keeping products shelf-stable, which is why they remain widespread. The concern is that parabens have been shown to act as weak estrogens. Laboratory work has demonstrated that extracts from over-the-counter products containing paraben preservatives can induce estrogen activity in tissue-culture bioassays, and the degree of that activity varies depending on the concentration of parabens, which itself differs between products and even between production batches of the same product.8Journal of the Endocrine Society. SAT-713 Novel Estrogenic Gene Regulation Induced by OTC Medications Containing Paraben Preservatives Is Dependent on Concentration that Varies Between Products and Batches
The real-world significance of this weak estrogenic effect is one of the more contested questions in toxicology. Parabens are metabolized quickly by the body and individual doses from a single product are small. But the issue is cumulative: if your toothpaste, moisturizer, shampoo, and deodorant all contain parabens, the aggregate exposure adds up throughout the day. Some European countries have restricted certain parabens in cosmetics, particularly the longer-chain versions like propylparaben and butylparaben, which show stronger estrogenic activity. For toothpaste, paraben-free alternatives are widely available and use different preservative systems, so switching is straightforward if you want to reduce your overall load.
Microbeads and Microplastics
Polyethylene microbeads were once common in toothpastes marketed as “deep cleaning” or “whitening,” serving as tiny scrubbing particles. The United States banned plastic microbeads from rinse-off cosmetics in 2015 through the Microbead-Free Waters Act, and similar legislation followed in Canada, the UK, and parts of the EU. However, not all countries have enacted bans, and some formulations still on the market contain microplastic-type particles that fall outside narrow legal definitions.
A systematic review of microplastic content in over-the-counter toothpastes found that prolonged use of toothpaste containing microbeads can aggravate gum inflammation, and that the risk of unintentionally swallowing these particles on a daily basis is potentially hazardous to health.9PubMed Central. Microplastic content of over-the-counter toothpastes – a systematic review Beyond your body, microbeads that go down the drain are too small for many water-treatment plants to filter, so they end up in waterways and eventually the food chain. If you see “polyethylene” or “polypropylene” on a toothpaste label, that is a plastic microbead. Natural alternatives like hydrated silica or calcium carbonate accomplish the same mild abrasion without the environmental footprint or the risk of particles becoming lodged along the gumline.
Activated Charcoal and Overly Abrasive Whiteners
Charcoal toothpaste has enjoyed a surge of popularity driven largely by social-media marketing and the idea that charcoal “detoxifies” or “deep cleans.” The laboratory evidence tells a less flattering story. An in-vitro study using scanning electron microscopy found that brushing with activated charcoal toothpaste significantly increased both the roughness and the abrasion of tooth enamel compared to standard toothpaste, and the damage was worse when paired with a medium-bristle brush.10PubMed Central. In Vitro Evaluation of Tooth Enamel Abrasion and Roughness Using Toothpaste with and Without Activated Charcoal: An SEM Analysis A separate study on bovine teeth confirmed the pattern, finding that charcoal whitening toothpaste produced significantly more surface roughness than conventional toothpaste, and that adding a peroxide bleaching agent on top of charcoal made things worse, not better.11PubMed Central. Effect of 16% Carbamide Peroxide and Activated-Charcoal-Based Whitening Toothpaste on Enamel Surface Roughness in Bovine Teeth: An In Vitro Study
Why does rougher enamel matter? Enamel does not regenerate. Once you abrade it, it stays abraded. Roughened enamel also stains more easily because pigments from coffee, tea, and wine settle into the micro-grooves, creating a vicious cycle where you use more abrasive paste to fight stains that the abrasive paste helped create. Most dental professionals recommend looking at a toothpaste’s Relative Dentin Abrasivity (RDA) value. Products with an RDA under 250 are considered safe by the American Dental Association, but many charcoal pastes have never been formally tested or rated. The particle size of any abrasive ingredient matters too: coarser particles cause more damage than fine ones, regardless of what the abrasive material is.12PubMed Central. Comparative Evaluation of Abrasiveness among Three Dentifrices: An In Vitro Study If whitening is your goal, a peroxide-based product used under dental guidance is a better bet than grinding your enamel down with charcoal.
Titanium Dioxide and Swallowing Risks
Titanium dioxide (listed as CI 77891 or E171) is a white pigment used to give toothpaste its bright white or opaque appearance. It has no therapeutic function; it is purely cosmetic. For most adults who spit out their toothpaste and rinse, the exposure is negligible. The concern centers on people who regularly swallow toothpaste, particularly children.
A pediatric case report documented a nine-year-old girl who developed yellow nail syndrome, a rare condition involving discolored nails, chronic cough, recurrent pneumonia, bronchiectasis, and chronic sinusitis. Energy-dispersive X-ray fluorescence detected titanium in her nail clippings. The exposure source was traced to her habit of swallowing children’s toothpaste. After she stopped swallowing toothpaste, her nail discoloration improved and her respiratory symptoms diminished.13PubMed Central. Titanium Dioxide in Toothpaste Causing Yellow Nail Syndrome One case report is not proof that titanium dioxide in toothpaste is broadly dangerous, and yellow nail syndrome is exceedingly rare. But it illustrates why swallowing toothpaste matters, and why a non-essential cosmetic additive deserves scrutiny in products marketed to children with flavors like bubblegum and strawberry.
The European Food Safety Authority re-evaluated titanium dioxide in 2021 and concluded it could no longer be considered safe as a food additive, citing concerns about genotoxicity that could not be ruled out. The EU subsequently banned E171 from food. Toothpaste is not food, but for children who swallow it regularly, the line between the two blurs.
The Fluoride Question for Young Children
Fluoride itself is not on the “avoid” list. It remains the single most evidence-backed ingredient for preventing cavities, and decades of research support its use. The issue is dose, specifically how much fluoride young children swallow before they learn to spit.
A study of early fluoride exposure found that using fluoride toothpaste before age six was a risk indicator for dental fluorosis, with roughly twice the odds compared to children who started later, and that beginning to brush before age two increased the severity of fluorosis significantly.14PubMed. Fluorosis risk from early exposure to fluoride toothpaste A Cochrane review confirmed that topical fluoride ingestion by young children with developing teeth can lead to dental fluorosis.15PubMed Central. Topical fluoride as a cause of dental fluorosis in children Fluorosis in its mild form shows up as faint white spots on the teeth and is mostly cosmetic, but moderate-to-severe cases can cause pitting and brown staining.
A systematic review and meta-analysis of toothpaste ingestion found that certain formulations with higher fluoride concentrations were associated with an increased risk of fluorosis, and emphasized that healthcare providers should promote safe toothpaste use in vulnerable populations, especially young children prone to accidental ingestion.16PubMed Central. Toothpaste ingestion-evaluating the problem and ensuring safety: systematic review and meta-analysis The practical advice is simple: for children under three, use a smear of toothpaste the size of a grain of rice; for children three to six, a pea-sized amount; and always supervise brushing to minimize swallowing. The goal is not to avoid fluoride but to control the dose.
Some Flavoring Oils Are Harsher Than You Would Expect
Toothpaste flavors seem harmless, but certain essential oils used for flavoring can be surprisingly aggressive on oral tissue. An in-vitro cytotoxicity study tested common toothpaste ingredients on reconstituted human gingival tissue and found that lemon oil, peppermint oil, and cinnamon oil all exceeded the concentration needed to kill half the cells at the levels typically present in commercial toothpastes. By contrast, ingredients like xylitol and polyethylene glycol showed no cytotoxic effects even at high concentrations.17PubMed Central. In vitro cytotoxicity (irritant potency) of toothpaste ingredients
This does not mean peppermint toothpaste is dangerous for everyone. The mouth’s natural saliva flow dilutes and washes away toothpaste quickly, and most people brush for only two minutes. But if you experience chronic oral irritation, burning sensations, or tissue peeling that does not resolve after switching away from SLS, the flavoring oils themselves may be worth investigating. Cinnamon-flavored products in particular are a known trigger for contact stomatitis, a localized allergic-type reaction. Unflavored or mildly flavored toothpastes exist for people who find that standard options irritate their mouths.
Why More Foam Does Not Mean Cleaner Teeth
A big reason SLS persists in most formulations is that consumers equate foaming with cleaning power. Research into how people perceive toothpaste has confirmed this: consumer ratings for “foam degree” and “foam liking” are strongly correlated with physical foam properties, and adding paste yield stress into the model made consumer satisfaction highly predictable based almost entirely on how the foam felt in the mouth.18PubMed Central. Sensory Investigation of Toothpaste Foam Using Rheology and Dynamic Foam Analysis In other words, foam is a sensory experience, not a cleaning mechanism. The actual removal of plaque comes from the mechanical action of your brush bristles and the chemical action of fluoride and other active ingredients. The surfactant’s job is to help spread the paste, which gentler surfactants accomplish without the tissue irritation.
This perception gap explains why many people try an SLS-free toothpaste, notice less foam, and assume it is not working as well. It is. You are just losing the suds, not the cleaning. If the reduced foam bothers you, brushing technique matters more than any ingredient: two full minutes, reaching every surface, with a soft-bristle brush, will remove plaque regardless of how much lather you generate.
Reading the Label in Practice
Toothpaste labels in the United States list active ingredients (usually fluoride) separately from inactive ingredients, which is where you will find SLS, parabens, DEA, titanium dioxide, and flavoring agents. In the EU, toothpaste falls under cosmetics regulations and uses INCI nomenclature, so sodium lauryl sulfate appears by that name, while titanium dioxide may be listed as CI 77891. Triclosan, where it still appears, is listed plainly.
A few practical tips for navigating the options: look for toothpastes that carry an ADA Seal of Acceptance or equivalent national endorsement, since these have been independently evaluated for safety and efficacy. “Natural” on a label is not a regulated term and does not guarantee the absence of any particular ingredient. Some natural toothpastes skip fluoride entirely, which trades a theoretical concern about additives for a well-proven loss of cavity protection. And charcoal products are almost never ADA-accepted, because the evidence for benefit is thin while the evidence for enamel harm is growing. If you want to minimize your exposure to the ingredients discussed here, the simplest approach is a fluoride toothpaste with a mild surfactant, no triclosan, no charcoal, and no parabens. Several major and boutique brands now fit that description without requiring you to visit a specialty store.