What parents need to understand about toddler diarrhoea, gut dysregulation and the path forward
Written and clinically reviewed by Bahee Van de Bor, RD, BCAPSc PGDipDiet, Specialist Paediatric Dietitian, former specialist dietitian at Great Ormond Street Hospital, with over 20 years of clinical experience in paediatric digestive health.
Quick answer
If your toddler keeps having loose stools but is growing well and eating normally, one possible explanation is functional diarrhoea, often called toddler diarrhoea.
We now know it does not always stop when the toddler years do. The Rome V criteria recognise functional diarrhoea from six months right through to eighteen years.
Normal blood and stool tests do not necessarily mean nothing is wrong. They look for infection, inflammation and coeliac disease. They do not tell us how the gut is actually working.
If your child is five or older, the picture is a little different, and there is a separate guide for that.
When the diarrhoea does not simply stop
Blood tests normal. Stool tests normal. Coeliac screen negative.
And your child is still not right.
Most children bounce back quickly after a stomach bug. The virus passes, the gut settles, and within a week or two things look normal again.
For some children that simply does not happen.
The loose stools carry on. Or they settle for a few days and come straight back. The pattern starts wandering: loose one week, hard the next, then loose again.
Or maybe there was never an illness at all.
Your child has simply always been like this. Loose stools for as long as you can remember, going on so long that you could not tell me when it started or what set it off. And in every other way they seem perfectly well.
So you try things. You take out the dairy. Then the gluten. You add more fibre. Or you try a probiotic. You wait.
Because that is what everyone tells you to do.
And something is still off.
By the time you find yourself reading a page like this one, it has usually been going on for months. Sometimes years. You have tried several sensible things, and you are no closer to knowing what is actually driving it.
That is what this post is for.
What is toddler diarrhoea?
Toddler diarrhoea is what most people call it when a young child keeps passing loose stools but is growing, eating and developing perfectly well.
What the stools usually look like
On the Bristol Stool Chart those stools usually sit at type 5 or type 6. Almost nobody says that out loud. What I actually hear in clinic is:
“Porridge-like”
“Like thick custard”
“Whipped ice cream”
“It just falls apart”
The clinical name is functional diarrhoea
Those descriptions tell me more than a number does. The texture is a clue to how quickly things are moving through, and how much water the gut is managing to pull back out along the way.
Now here is the part most parents are never told.
Toddler diarrhoea is the everyday name. It is not the clinical one.
The clinical name is functional diarrhoea, and it is a diagnosis in its own right. Not a leftover label for when the tests come back empty.
What Rome V says, and what changed
The Rome V criteria changed recently, in a way that matters.
The diagnosis now runs all the way to eighteen years, because studies kept finding it in school-age children and teenagers. It used to stop much earlier.
The thresholds also differ by age, since how often children open their bowels changes as they grow.
Under four, it means four or more painless bowel movements a day.
From four upwards, more than two a day. Either way, at least a quarter of the stools are unformed, and it has been going on for at least two months.
Symptoms can start any time from six months.
It is a positive diagnosis, made on the pattern. It still needs a proper assessment first, to be sure nothing else explains the symptoms.
Functional diarrhoea can be diagnosed in young children. You do not have to wait until they are older for it to be taken seriously.
And IBS is a separate question. It is not diagnosed before age six, because no studies have described it in younger children. That is a gap in the evidence, not a judgement about your child.
What to do if your toddler has diarrhoea now
If this has only just started, the first job is fluid, not diet.
Young children get dehydrated faster than adults do, especially if there is vomiting alongside it.
NHS guidance is to offer small sips often, keep breastfeeding or formula feeding as normal if your child is a baby, and let them go back to their usual food as soon as they want it.
Most bouts settle by themselves in five to seven days.
The rest of this post is for the other situation. The one where it did not settle, the tests came back clear, and you are still here months later wondering what you have missed.
Toddler diarrhoea: when to worry
This is the question I get asked most, and I want to answer it properly rather than with a vague “see your GP if you are concerned”.
First, the reassuring part.
A toddler who is growing well, eating happily and full of beans, but producing loose stools, is generally reassuring.
This is the pattern we often see with functional diarrhoea.
A few things need more than a routine appointment, and the NHS is specific about which.
Yellow-green or green vomit in a child means calling 999 or going to A&E.
Signs of dehydration in a child under five, such as fewer wet nappies, mean calling 111 for urgent advice.
What follows are the features that suggest something other than functional diarrhoea is going on.
They come from Table 3 of the Rome V criteria, which lists features clinicians consider when assessing chronic diarrhoea.
I have split it in two, because half of the original list is bloodwork you cannot see at home.
Things you might notice yourself
- Losing weight, or drifting off their growth curve
- Going off their food
- Signs of dehydration
- Diarrhoea that wakes them in the night
- Very large volumes
- Vomiting that keeps returning, or is green, or happens at night
- Blood in the stool
- Blood in the wee
- Tummy pain alongside the diarrhoea
- A swollen or distended tummy
- Swelling elsewhere, such as the face, hands or feet
- Fever
- A rash, or swollen, painful joints
- Passing a worm or other parasite
- A family history of inflammatory bowel disease, coeliac disease, or bowel polyps or bowel cancer
Things your GP may find or test for
- Signs of malnutrition
- Tenderness when they examine the tummy
- Ileus, meaning the bowel is not moving along as it should
- Kidney failure
- Protein in the urine
- Anaemia
- A low platelet count
- A raised white cell count
- Raised calprotectin, CRP or ESR
If any of these apply to your child, speak to your GP rather than trying to manage the diarrhoea through dietary changes alone.
If none of them do, and everything still is not right, that is the situation the rest of this post is about.
Why normal tests do not mean nothing is wrong
Why normal tests do not mean nothing is wrong
This is the thing I find myself explaining most often to families when they first contact me.
Standard blood tests, stool cultures and coeliac screens are designed to detect structural disease, inflammation, infection, autoimmune damage.
They are not designed to measure how the gut is functioning from day to day.
When a child has ongoing loose stools despite normal investigations, the gut may be functioning differently in ways that simply do not show up on routine testing.
The architecture is intact.
But the way the gut is working is out of sync.
Normal results are not the end of the story.
They are the beginning of a different kind of question.
The pattern most parents are never told about (overflow)
This is the finding that surprises families most, and it is more common than most people realise.
Some children who appear to have chronic diarrhoea are actually constipated.
When stool builds up in the colon over time, liquid from higher in the gut can leak around it and pass as what looks like diarrhoea or soiling. This is called overflow.
It is described in the Rome V diagnostic criteria for functional constipation in children, and it is one of the reasons that treating loose stools without first understanding the full picture can make things considerably worse rather than better.
If your child’s stools swing unpredictably between hard and loose, or if they soil without seeming to notice, this is worth discussing with a specialist before any dietary changes are made.
Can a stomach bug trigger ongoing gut problems?
Yes, and parents rarely hear this. Most children recover fully after gastroenteritis, but in some the gut does not recalibrate.
A single bout of illness can change how the gut moves food, reduce microbial diversity and leave the gut more sensitive long after the infection clears.
Early antibiotic use raises that risk too.
If your child is still not right weeks or months after a stomach bug, this post explains what is happening inside the gut and what actually helps.
Is it toddler diarrhoea or IBS?
Is it toddler diarrhoea or IBS?
Parents ask me this often, and the difference is clearer than many articles suggest.
Pain is the key difference
Functional diarrhoea, the clinical name for toddler diarrhoea, involves recurrent loose stools without pain.
That is part of the diagnostic pattern, not an incidental detail.
IBS is different because recurrent tummy pain is an essential feature.
The pain occurs alongside a change in how often the child opens their bowels or what their stools look like, and it may be related to having a bowel movement.
If your child has persistent loose stools, is growing well and does not experience pain, functional diarrhoea may fit the pattern.
A proper assessment is still important to check that nothing else is contributing.
If tummy pain is a regular part of the picture, that needs assessing separately rather than assuming it is toddler diarrhoea.
Rome V does not diagnose IBS before six
The latest Rome V criteria apply the diagnosis of IBS from age six onwards.
This is not a judgement about your child’s symptoms.
It reflects a gap in the evidence because IBS has not been adequately studied or described in children younger than six.
A younger child can still have real and disruptive digestive symptoms that need assessing. They simply would not be given that particular diagnosis yet.
If your child is six or older
Persistent loose stools in children aged six and over need a slightly different assessment.
When recurrent tummy pain is also present, IBS becomes one possible explanation alongside other causes.
I cover this separately in: Loose stools in school-age children: what it means when tests are normal
Why things may not have improved yet
Why things may not have improved yet
By the time most families contact me, they have already tried several things.
Dairy removed. Fibre increased. A probiotic added. Gluten reduced. Multiple appointments attended. Different advice received at each one.
Symptoms may improve briefly and then return. Or they may not improve at all.
This is not because families have failed or have not tried hard enough.
Persistent loose stools can look similar from the outside while having very different explanations.
Functional diarrhoea, overflow constipation and changes following a stomach bug do not all need the same approach.
Without understanding the whole pattern first, dietary changes may not address what is actually driving the symptoms. They can also make it harder to identify what is helping and what is not.
Symptoms naturally fluctuate too. A few better days after removing a food do not necessarily prove that food was the problem.
The answer is not another blanket food exclusion.
It is identifying the pattern and then reviewing the dietary factors most likely to matter, rather than removing whole food groups without a clear clinical reason.
Foods that may worsen toddler diarrhoea
Food is not always the cause of toddler diarrhoea.
However, a few common dietary patterns may contribute to loose stools or make an already sensitive gut harder to settle.
Fruit juice, smoothies, fructose and sorbitol
Fruit juice and smoothies can contribute to loose stools, particularly when a toddler drinks them regularly or in large amounts.
Some contain more fructose than the small bowel can absorb at once.
Others, particularly apple, pear and prune juice, also contain sorbitol.
Any fructose or sorbitol that is not fully absorbed travels into the large bowel, where it draws in water and can make stools looser.
This does not mean that fruit needs to be removed from your child’s diet.
Whole fruit is eaten in age appropriate amounts and comes with fibre, so it is handled differently from fruit that has been juiced or blended.
If your toddler regularly drinks juice or smoothies, look at the amount and frequency before cutting out fruit or starting a restrictive diet.
Water and their usual milk should generally be their main drinks.
The NHS guidance on drinks for babies and young children explains when fruit juice can be offered and recommends keeping it to mealtimes.
If getting your toddler to drink water at all is the harder problem, start here: 7 ways to get your child to drink water
Very high fluid intake
Very high intakes of non-milk drinks may contribute to persistent loose stools in some young children.
This means drinking an unusually large volume for the child’s size, rather than ordinary drinking or being offered water regularly.
It may be worth looking at the overall pattern if a child is constantly sipping and drinks are replacing food. Normal fluid intake should not be restricted.
This applies only to long-standing loose stools in a child who is otherwise well. Children need additional fluids during acute diarrhoea or vomiting, particularly when there is a risk of dehydration.
Fibre intake
Fibre is important, but simply adding more is not always helpful when stools are already loose.
Bran cereals and large amounts of wholegrain foods can speed up the bowel in some children.
This does not mean cutting out fibre.
It means getting the type and amount right for that individual child.
Too little fat
Young children need dietary fat for energy, growth and development.
A very low-fat diet may also allow food to move through the gut more quickly.
This can become a problem when families switch entirely to low-fat products or remove foods such as dairy without replacing the energy and fat they previously provided.
A useful rule of thumb is to include a portion of healthy fat with each meal.
This might be a spoonful of smooth nut butter spread over a slice of toast at breakfast, a few slices of avocado with lunch, or olive oil used to cook the family meal.
What about FODMAPs?
FODMAPs are fermentable carbohydrates.
They occur naturally in foods such as wheat-based products, some fruits and vegetables, pulses and lactose-containing dairy products.
They can contribute to bloating, wind, tummy pain and changes in stool pattern in some people.
However, most of the paediatric research relates to older children with IBS or other pain-related gut-brain interaction disorders, not toddlers with functional diarrhoea.
Some children may be sensitive to one or more particular FODMAP groups.
That does not mean that every FODMAP is a problem or that they need to follow a blanket low-FODMAP diet.
A strict low-FODMAP diet is not a first-line treatment for toddler diarrhoea.
In fact, the joint ESPGHAN and NASPGHAN guideline does not suggest using a strict low-FODMAP diet even for children aged 4 to 18 with IBS or functional abdominal pain because the evidence is insufficient.
That guideline does not cover functional diarrhoea.
This matters because a low-FODMAP diet temporarily restricts many nutritious everyday foods.
In a young child, a poorly planned restriction can unnecessarily narrow dietary variety and make it harder to meet their nutritional needs.
If you suspect your child reacts to a particular FODMAP, ask for a careful assessment from an experienced paediatric gastroenterology dietitian.
That assessment shows whether a targeted dietary trial makes sense, and it plans how to bring any restricted foods back in.
What about food intolerance tests?
Do not use commercial food intolerance tests, including hair analysis and food-specific IgG or IgG4 panels, to decide which foods your child must avoid.
Studies have not found these tests reliable for diagnosing food intolerance.
Food-specific IgG usually reflects everyday exposure to a food, and may even point towards tolerance rather than showing that the food is causing symptoms.
The results often identify multiple everyday foods as supposed triggers.
Families then remove several nutritious foods unnecessarily, which can narrow a child’s diet, affect growth and build food anxiety. Meanwhile the real cause goes unassessed.
The ASCIA position paper on non-evidence-based allergy and intolerance testing explains why allergy specialists advise against these tests.
I have written about this in more detail here: Are food intolerance tests accurate?
Probiotics and antibiotics
Antibiotics can alter the gut microbiome, and some children develop diarrhoea during or shortly after a course of antibiotics.
This does not mean that every child needs a probiotic.
Probiotic evidence is specific to the strain and the reason for using it.
Certain strains may reduce the risk of antibiotic-associated diarrhoea when started alongside the antibiotic.
However, this evidence relates to preventing diarrhoea associated with antibiotic treatment. It does not show that probiotics will resolve persistent toddler diarrhoea weeks or months later.
If loose stools continue, look at the whole pattern first. Then consider the other possible causes, rather than assuming a probiotic will “restore” your child’s gut bacteria.
For more information about when probiotics may help and which strains have been studied, read: Does My Child Need Probiotics After Antibiotics?
What one father said after twelve weeks
Here is what one father wrote after finishing the programme.
His son had been unwell since he was two.
“Thriving, practically symptom free, and with a much less restrictive diet.”
“We just completed the 12 week program with Bahee to help our 5 year old son who’s had issues since he was 2. Within the first few sessions Bahee identified the primary triggers and within the first month all symptoms had practically disappeared. Bahee achieved in that first month something the NHS hadn’t come close to in over 3 years of trying. We’re so grateful for everything and thrilled that our son is now thriving practically symptom free and with a much less restrictive diet.”
What structured support looks like
What structured support looks like
In my 12-week, 1-to-1 clinical programme, the Happy Belly Club®, we do not begin by removing more foods.
We start with the Identify phase of the Happy Belly Formula™.
I review your child’s medical and gut history, growth, stool and symptom patterns, usual food and drink intake, and everything you have already tried.
This helps us distinguish between problems that can look similar from the outside, including functional diarrhoea, overflow associated with constipation, and symptoms that developed following an infection or course of antibiotics.
Once we understand which factors are most likely to matter, we move into the Restore phase.
I tailor every recommendation to your child, and we introduce them in a deliberate order.
Depending on the assessment, this might include adjusting the balance of fluid, fibre or fat, addressing constipation, reviewing suspected food triggers or recommending further medical assessment.
The Thrive phase focuses on maintaining progress, returning to the broadest diet possible and helping you feel confident about managing future changes in symptoms.
Because we work together over 12 weeks, I can review how your child responds and adjust the plan as we go. You no longer have to work out on your own whether a change has helped, or decide what to try next.
Frequently Asked Questions
Is toddler diarrhoea the same as IBS?
No. Functional diarrhoea, the clinical term for toddler diarrhoea, is painless. The child has frequent loose stools but is otherwise well and growing as expected.
IBS requires recurrent abdominal pain associated with bowel movements or a change in stool frequency or form. Under the Rome V criteria, IBS is not diagnosed in children younger than six.
If tummy pain is a regular part of your toddler’s symptoms, they need a different assessment rather than assuming it is toddler diarrhoea.
Why does my child keep having loose stools despite normal test results?
Normal results can be reassuring, but they only provide information about the conditions that were tested for. They do not automatically explain why loose stools are continuing.
Functional diarrhoea is identified by looking at the whole clinical pattern, including your child’s growth, stool history, diet, symptoms and any warning signs.
If symptoms persist or change, further assessment may still be needed even when previous tests were normal.
Could my child’s loose stools actually be constipation?
Possibly. When stool builds up in the bowel, softer or liquid stool can pass around it. This is called overflow and it can look like diarrhoea.
Clues can include withholding, painful or very large stools, long gaps between bowel movements, soiling or stools that alternate between hard and loose.
Loose stools alone do not prove that a child is constipated. The full bowel pattern should be assessed before changing their diet or starting treatment.
Can a stomach bug cause ongoing gut problems?
Most children recover fully from gastroenteritis. However, some continue to experience loose stools, constipation, bloating or tummy pain after the infection has cleared.
This may reflect temporary changes in digestion, gut movement or gut sensitivity. In toddlers, persistent symptoms should not automatically be labelled as IBS.
You can read more in Can a stomach bug trigger IBS in children?
Should I try a probiotic for my child’s loose stools?
Not necessarily. There is no single probiotic that treats every cause of loose stools, and probiotic evidence is specific to the strain and the condition being treated.
For example, certain strains may reduce the risk of antibiotic-associated diarrhoea when started alongside antibiotics. This does not mean that a general children’s probiotic will treat persistent functional diarrhoea.
If your child’s loose stools continue, the priority is to understand the cause rather than working through different probiotic products.
For more information, read Does my child need probiotics after antibiotics?
Should I get a food intolerance test for my child?
Commercial tests such as food-specific IgG or IgG4 panels, hair analysis and bioresonance are not recommended for diagnosing food intolerance.
Food-specific IgG commonly reflects exposure to a food rather than showing that the food is causing symptoms. Hair analysis and bioresonance also have no validated role in diagnosing food allergy or intolerance.
These results can lead families to remove several nutritious foods unnecessarily, making a child’s diet narrower without identifying the real cause of their symptoms.
If a food allergy or intolerance is suspected, assessment should be based on the clinical history, with validated testing or a carefully planned exclusion and reintroduction where appropriate.
Read more in Are food intolerance tests accurate?
References
Di Lorenzo C, Saps M, Chumpitazi BP, et al. Lower and biliary disorders of gut-brain interaction: child and adolescent. Gastroenterology. 2026;170(6):1367-87.
Groen J, Gordon M, Chogle A, et al. ESPGHAN/NASPGHAN guidelines for treatment of irritable bowel syndrome and functional abdominal pain-not otherwise specified in children aged 4-18 years. J Pediatr Gastroenterol Nutr. 2025;81:442-71.
Greene HL, Ghishan FK. Excessive fluid intake as a cause of chronic diarrhea in young children. J Pediatr. 1983;102(6):836-40.
Australasian Society of Clinical Immunology and Allergy. Evidence-based versus non evidence-based allergy tests and treatments. ASCIA position paper; 2025.
National Health Service. Drinks and cups for babies and young children. NHS; 2025.
About the Author
About the author
RD, BCAPSc PGDipDiet, Specialist Paediatric Dietitian
Bahee is a Registered Paediatric Dietitian specialising in children’s digestive health, with over 20 years of clinical experience including 12 years at Great Ormond Street Hospital. In June 2026 she presented at the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) on nutritional microbiome therapies following antibiotics.
Through the Happy Belly Club®, Bahee works with families whose children experience persistent constipation, diarrhoea, tummy pain and IBS-type symptoms.
If your child has ongoing gut symptoms and you would like to find out whether Bahee may be able to help, you can book a free 15-minute Discovery Call. The call is not a clinical consultation. It is an opportunity to explain briefly what has been happening and find out whether the Happy Belly Club® may be suitable.
Book your free 15-minute Discovery Call
