What parents need to understand about overflow diarrhoea and overflow constipation in children
Medically 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.
Your child seems to have diarrhoea.
Loose stools. Skid marks in their underwear. Unexpected accidents.
Perhaps the school has mentioned accidents during the day.
Maybe your child is changing their underwear more often than usual.
Or you are finding dirty pants hidden at the bottom of the wash basket and nobody can explain why.
The last thing anyone is thinking about is constipation.
But sometimes constipation is exactly what is causing the loose stools.
This is one of the most commonly missed patterns I see in clinic.
And it is one of the most important to understand, because treating it as diarrhoea, by cutting out foods or reducing fibre, can make the underlying problem significantly worse.
Why parents get confused
When a child has loose stools or accidents, the natural assumption is diarrhoea.
Loose stool means diarrhoea. Constipation means no stool.
That logic makes sense. But the gut does not always follow that logic.
In overflow constipation, a child can have loose stools every day and still be severely constipated.
The two are not mutually exclusive.
In fact, the loose stools are often a direct consequence of the constipation itself.
Understanding why this happens changes everything about how you approach treatment.
What is overflow constipation (also called overflow diarrhoea)?
As more stool accumulates, it becomes harder and more impacted.
Liquid stool from higher up in the gut cannot pass through normally, so it leaks around the blockage and passes as what looks like loose stools, accidents or soiling.
The motorway analogy helps here.
Imagine a traffic jam on a motorway.
Constipation is the traffic jam.
The loose stool is the motorbike squeezing around the outside.
When you see the motorbike, you assume the road is clear. But the real problem is the traffic jam behind it.
Parents see the loose stool and treat the diarrhoea. But the real problem is the constipation causing it.
The signs I look for in my clinic
When stool builds up in the colon over time, the colon stretches to accommodate it.
Overflow constipation does not always look the way parents expect.
The signs are often subtle and easily misread.
In my clinic, I look for:
- Skid marks or soiling in underwear, often without the child noticing
- Small, frequent stools rather than one complete bowel movement
- Alternating between loose stools and periods of no stool at all
- Tummy pain, particularly in the lower abdomen
- Reduced appetite, early fullness, or seeming uninterested in meals
- A sense of incomplete emptying, after going to the toilet
- Occasional stools that seem surprisingly large for a child their age. Many parents describe stools that look more like something an adult would pass. This can be a clue that stool has been collecting in the bowel for a long time.
- Frequent wee accidents, needing the toilet urgently, or recurrent urinary symptoms, which can sometimes occur because a stool-filled bowel places pressure on the bladder
- A history of withholding, even if it seems to have resolved
Not every child will have all of these.
But when several are present together, overflow is often part of the picture.
You can use the child poo chart to help identify what type of stools your child is passing and what that might mean.
The symptom that surprises most parents
Many parents arrive in the clinic saying something along the lines of:
“They cannot be constipated. They go every day.”
This is one of the most important misconceptions to address.
Daily bowel movements do not rule out constipation
A child can open their bowels every single day and still be significantly constipated if what is passing is overflow rather than a complete, comfortable bowel emptying.
The stool that passes is liquid, leaking around the blockage.
The blockage itself remains.
Frequency alone tells you very little.
What matters is whether the bowel is actually emptying properly.
Why stopping laxatives often makes things worse
When parents see loose stools or accidents, the instinct is often to reduce or stop any laxatives the child is taking, assuming the laxative is causing the loose stools.
In overflow constipation, this is usually the opposite of what the bowel needs.
The loose stools are a symptom of constipation, not the laxative.
Stopping the laxative removes the thing that is trying to clear the blockage and allows the constipation to worsen further.
If your child is on laxatives and still having accidents or loose stools, read my post on why children keep getting constipated even on laxatives for a fuller explanation of what is usually maintaining the cycle.
Why cutting out foods rarely solves the problem
When a child has frequent loose stools, parents understandably look for a dietary cause.
Dairy goes first. Then gluten. Eggs. Then fruit.
In overflow constipation, none of these changes addresses the underlying problem because the loose stools are not caused by a food intolerance.
They are caused by constipation.
Removing foods without identifying the underlying pattern can narrow the diet significantly without improving symptoms.
In some cases, it makes things worse by reducing the fibre and variety the gut needs to recover.
If you have been told your child may have a food intolerance and are considering cutting out dairy, read does dairy cause constipation in children before removing it from the diet.
If you are wondering whether eggs might be contributing, read do eggs cause constipation in children for a clearer picture of when food genuinely matters.
What treatment actually looks like
This is the thought reversal that changes how parents approach the problem.
The goal is not to stop the diarrhoea.
The goal is to clear the constipation causing the diarrhoea.
When the blockage is cleared and the bowel is properly emptied, the overflow resolves on its own.
The loose stools stopped not because the diet changed but because the underlying constipation was finally addressed.
Treatment usually involves ensuring laxatives are at an adequate dose and given consistently, allowing the bowel enough time to clear the accumulated stool, and then maintaining that with a structured approach rather than stopping laxatives too early.
This process takes time.
The bowel has often been stretched for weeks or months and needs time to recover its normal tone and function.
Soft stools on laxatives do not mean the constipation has resolved.
Full recovery means the bowel empties completely and regularly without constant management.
When to seek help
It is worth speaking to a specialist if:
- Your child has frequent loose stools or accidents, but you are not sure whether constipation is involved
- Laxatives do not seem to be helping, or symptoms keep returning
- Your child is soiling without appearing to notice
- You have been told it is diarrhoea, but the treatment is not working
- Your child is avoiding the toilet or showing signs of withholding
Red flag symptoms that always need prompt medical review include blood in the stool, significant weight loss, poor growth, or symptoms that have been present since birth.
What structured support looks like
In my clinical programme, the Happy Belly Club®, I work with families through a structured 12-week process.
Before any treatment change is recommended, I look at the full picture.
The stool pattern, the history of the constipation, what has already been tried, and whether overflow is part of what is maintaining the cycle.
That assessment is often what families have been missing.
From there, we work through the Happy Belly Formula.
Identify, Restore, Thrive.
Addressing the constipation properly, in the right sequence, so the bowel has the best chance of recovering normal function.
For many families, understanding that the loose stools are a sign of constipation rather than a separate problem is the turning point that finally makes the whole picture make sense.
If you would like to understand whether this approach is right for your child, you can book a free 15-minute Discovery Call.
No pressure. Just a clear conversation about what is going on and whether I can help.
Frequently Asked Questions
Yes. In overflow constipation, liquid stool leaks around a blockage in the colon and passes as what looks like loose stools or accidents. The child may appear to have diarrhoea while being significantly constipated at the same time.
Yes. Daily bowel movements do not rule out constipation. If what is passing is overflow rather than a complete emptying of the bowel, the underlying constipation remains. Frequency alone does not tell you whether the bowel is functioning properly.
When stool has been building up in the colon for a long time, the nerves that signal fullness can become less sensitive. The child loses the normal urge to go and may not feel the soiling happening. This is a sign that the constipation has been present for some time and needs proper treatment.
Not without speaking to a clinician first. In overflow constipation, loose stools are caused by the constipation rather than the laxative. Stopping the laxative often removes the thing helping to clear the blockage and can make the underlying problem worse.
If accidents are continuing despite laxative treatment, it may mean the dose is not yet adequate, the constipation has not fully cleared, or the laxative was reduced too early. A structured assessment can help identify what is maintaining the cycle.
About the Author
Bahee Van de Bor is a Registered Paediatric Dietitian specialising in children’s digestive health.
She has over 20 years of clinical experience, including 12 years working at Great Ormond Street Hospital.
Bahee works with families whose children experience constipation, diarrhoea, tummy pain and IBS-type symptoms through her clinical programme, the Happy Belly Club®.
If you are concerned about your child’s ongoing gut symptoms, you can learn more about the Happy Belly Club® or request a Discovery Call to discuss your child’s situation.
