Most of us choose our children's toothpaste based on the character on the tube, the flavour they will actually tolerate, or the brand we grew up with ourselves. Very few of us have ever read the ingredient list. This article is for the parents who are starting to wonder whether they should.
The twice-daily habit nobody questions
There are very few products your child uses more consistently than toothpaste. Twice a day, every day, from the moment their first tooth appears. That is over 700 applications a year, before they even start school.
For most of that time, we assume the product is straightforwardly safe. It sits in the bathroom alongside the bubble bath and the gentle shampoo. It comes in bright packaging with friendly characters. It is recommended by dentists. Surely that is enough?
But a growing number of parents, particularly those already paying attention to ingredients in food, skincare, and cleaning products, are beginning to ask a more specific question: what is actually in this? And does it matter that my child swallows some of it every single time they brush?
These are reasonable questions. And the answers are more interesting than the packaging suggests.
Children swallow toothpaste. This is not a niche concern.
Before looking at specific ingredients, it is worth establishing something that is often underappreciated: children swallow a meaningful amount of toothpaste during brushing, particularly young children who have not yet developed reliable spitting technique.
Research published in the International Journal of Environmental Research and Public Health found that young children can ingest between 0.5mg and 1.5mg of fluoride per brushing session from toothpaste alone, depending on age, brushing supervision, and the amount used (1). For context, a pea-sized amount of standard children's fluoride toothpaste contains approximately 0.5mg of fluoride.
This is why toothpaste tubes carry warnings. It is also why the question of what children are regularly ingesting, in small amounts, twice daily, across years of development, is worth understanding more clearly.
SLS: what it is and why it is worth a closer look
Sodium lauryl sulphate, almost always listed as SLS on ingredient labels, is a synthetic surfactant used in toothpaste to create foam. It is also found in shampoos, body washes, and cleaning products. Its primary function is to help spread the toothpaste around the mouth and give the sensation of a thorough clean.
SLS does not clean teeth. The mechanical action of brushing does that. SLS creates the foam that makes brushing feel effective.
For most healthy adults, SLS in toothpaste is well tolerated. But there are specific concerns worth knowing about, particularly in the context of children and repeated daily exposure.
SLS and oral tissue irritation
A number of peer-reviewed studies have found an association between SLS-containing toothpastes and recurrent aphthous ulcers, more commonly known as mouth ulcers. A double-blind crossover study published in the Journal of Clinical Periodontology found that participants using SLS-free toothpaste experienced significantly fewer mouth ulcers than those using SLS-containing formulas (2). For children who experience recurrent mouth ulcers, SLS is one of the first variables worth considering.
SLS and the oral microbiome
This is where the conversation becomes particularly relevant to anyone thinking about children's long-term oral health.
The oral microbiome is the complex community of microorganisms that live in the mouth. In a balanced state, these microbes support oral health, help regulate the local immune environment, and form part of the broader microbial ecosystem that connects the mouth to the gut. Research increasingly supports the view that a diverse and balanced oral microbiome is associated with better oral and systemic health outcomes (3).
SLS is a detergent. Its surfactant action does not distinguish between harmful bacteria and the beneficial microbes that form part of a healthy oral environment. Research suggests that repeated use of SLS-containing products may influence the composition of the oral microbiome, though the long-term implications of this in children are still being studied (4).
For parents already thinking carefully about gut microbiome health, this is a meaningful consideration. The mouth is the beginning of the digestive tract. What happens in the oral microbiome does not stay there.
The oral-gut connection: why the mouth matters more than we thought
One of the most significant developments in microbiome science over the past decade is a clearer understanding of the oral-gut axis: the bidirectional relationship between the microbial communities of the mouth and the digestive system.
Research published in the Journal of Dental Research found that oral bacteria can travel through the digestive tract, influencing gut microbiome composition and immune responses (5). Studies exploring the oral-gut microbiome axis highlight how the microbial ecosystems of the mouth and gut are interconnected in ways that are only beginning to be fully understood (6).
For children, whose microbiomes are still developing and establishing patterns that may persist into adulthood, this interconnection is particularly relevant. The products used in the mouth twice daily are not interacting with an isolated system. They are interacting with the beginning of a much larger biological network.
This does not mean that standard toothpaste is harming your child. It does mean that the ingredients in daily oral care products are worth understanding with the same care that many parents now apply to food labels.
A note on fluoride
Fluoride deserves a measured, evidence-aware treatment rather than either uncritical endorsement or unnecessary alarm.
Fluoride has been a cornerstone of dental public health for decades, and major dental organisations including the NHS and the British Dental Association continue to recommend fluoride toothpaste for children as an effective tool for cavity prevention (7). This guidance is based on a substantial body of evidence and is not something to dismiss lightly.
At the same time, it is legitimate for parents to be aware of the following. Excessive fluoride ingestion during early childhood, when teeth are still developing, is associated with dental fluorosis, a condition that affects the appearance of tooth enamel and in its milder forms presents as white spots or streaks (8). This is why age-appropriate amounts and supervision during brushing are consistently recommended by dental professionals.
For parents who wish to explore fluoride-free alternatives, biomimetic hydroxyapatite is the most extensively researched option currently available. Hydroxyapatite is a calcium phosphate mineral that makes up approximately 97% of tooth enamel. A growing body of clinical research, including a systematic review published in the Canadian Journal of Dental Hygiene, suggests that hydroxyapatite toothpaste may offer comparable remineralisation to fluoride in certain contexts, particularly for early-stage enamel wear (9). It is also biocompatible and considered safe if swallowed, which is a practical consideration for young children.
Whether a family chooses fluoride or a fluoride-free alternative, the most important factors remain consistent brushing technique, appropriate amounts, and supervision for younger children.
The developing microbiome: why early years matter
There is a broader context worth understanding here. The first years of life represent a critical window for microbiome development. The communities of bacteria established in early childhood, both in the gut and in the mouth, appear to have lasting influence on immune function, metabolic health, and susceptibility to certain conditions (13).
This does not mean that a single product determines a child's microbiome trajectory. It does mean that the cumulative inputs of early life, including the oral care products used twice daily from infancy, are worth thinking about with some care.
Research into the oral microbiome of children is still developing. But the direction of travel in the science is clear: a diverse, balanced oral microbiome appears to be associated with better oral health outcomes, and products that support rather than disrupt that balance may be worth prioritising (3,14).
Practical guidance for parents
None of this is intended to create anxiety around a routine that, done consistently, is genuinely important for children's oral health. Brushing twice daily remains one of the most effective things parents can do to protect their children's teeth.
These are simply the questions worth asking when choosing which product to use.
Check the ingredient list before buying. The character on the packaging tells you nothing about what is inside it.
Use the right amount. For children under three, a smear. For children three and over, a pea-sized amount. Supervise brushing and encourage spitting where developmentally appropriate.
Consider what your child is likely to swallow. Younger children ingest more toothpaste than older ones. For this age group in particular, the safety profile of individual ingredients is worth factoring into your choice.
Look beyond fluoride as the only metric. Effective oral care for children involves brushing technique, diet, hydration, and regular dental visits, not toothpaste alone.
If your child experiences recurrent mouth ulcers, consider trialling an SLS-free formula for a period and observing whether frequency changes.
A final thought
The toothpaste conversation is not about fear. It is about information.
Parents routinely read food labels, question ingredients in skincare, and think carefully about what their children are exposed to across the day. Oral care deserves the same consideration, not least because it involves a product used inside the body, twice daily, for a lifetime. Understanding what is in your child's toothpaste does not require abandoning everything you currently use. It simply means making a choice that is informed rather than assumed. Your child's oral microbiome is part of a larger biological system that connects their mouth to their gut, their immune function, and their long-term health. The products you choose to support it are worth choosing carefully.
