Few childhood problems carry as much quiet shame as soiling. Parents rarely raise it with friends. Children hide underwear in cupboards. Schools send home notes. And somewhere in the middle, everyone quietly concludes that the child is being lazy, defiant, or simply “not trying.”
In clinic, I see this assumption constantly, and it is almost always wrong. In this post I want to walk through what is actually happening inside a soiling child’s body, why the gut bacteria are part of the story, and how I approach treatment. The video at the bottom of this page covers the same ground in five minutes if you prefer to watch.
Overflow, not defiance
Decades of research point to the same conclusion: the overwhelming majority of soiling cases, roughly 80 to 90 per cent, are retentive. In plain language, the child is constipated, and what leaks out is overflow.
Here is the sequence. Hard stool accumulates in the rectum. Over weeks, the rectum stretches to accommodate it, and a stretched rectum gradually stops sending the “time to go” signal. Softer stool from higher in the bowel then seeps around the hardened mass, and because sensation has dulled, the child genuinely does not feel it happen.
This is why so many parents tell me their child “doesn’t even seem to notice.” They are right. The child is not ignoring the urge; the urge has gone quiet.
How it usually starts
Almost every case I see traces back to a single painful bowel motion. A child learns that pooing hurts, so they hold on. Holding makes the next stool harder, which hurts more, which reinforces the holding. Within weeks the cycle is self-sustaining.
The common triggers are predictable: toilet training, starting school and refusing the school toilets, a tummy bug with dehydration or a course of antibiotics, or a small anal tear from one hard stool. None of these are behavioural failures. They are ordinary events that happen to tip a child into withholding.
Once you understand this, two things follow. First, the embarrassment and avoidance you are seeing are consequences of soiling, not its cause. Second, punishment is counterproductive. A child who is frightened or ashamed holds on harder. And over time, anxiety layers itself on top of the original constipation, which makes the picture more complicated to unwind.
Where the microbiome comes in
When researchers examine the gut bacteria of constipated children, they repeatedly find lower levels of beneficial groups such as Lactobacillus and Bifidobacterium, along with shifts in the compounds those bacteria produce. One of the most important is butyrate, a short-chain fatty acid that nourishes the bowel lining and supports motility.
There is also a signalling dimension. Around 90 per cent of the body’s serotonin is produced in the gut, and serotonin is a major driver of bowel movement. The microbiome influences that signalling directly.
I want to be honest about the state of the evidence here: cause and effect are not fully untangled. A sluggish bowel alters the microbiome, and an altered microbiome slows the bowel. It is a loop. But a loop can be interrupted from several points, and that is exactly what treatment aims to do.
A word on probiotics, because parents often reach for them first. The trials showing benefit in paediatric constipation used specific, researched strains. Not all strains perform equally, and some very popular ones, Lactobacillus rhamnosus among them, showed no benefit. A generic children’s probiotic from the supermarket shelf is not interchangeable with a studied strain. And even the right probiotic is a support, not the plan.
My three-step approach: soften, feed, retrain
1. Clear the backlog
Once impaction is present, fibre alone almost never shifts it. The first job is to soften and clear retained stool. I do this with herbal medicine alongside dietary changes, and for most children this is effective without pharmaceutical laxatives. The herbs fall into a few groups: demulcents to soothe the bowel lining, stool softeners, nervine tonics to restore normal muscle function, and gentle bowel laxatives where needed. For long-standing or stubborn cases, a practitioner can prescribe stronger therapeutic herbs.
Then comes the part most families underestimate. Stools need to stay soft for a minimum of three months, and sometimes up to twelve. That is how long a stretched rectum takes to regain tone and sensation. Stopping too early is the single most common reason soiling returns.
2. Feed the microbiome
This is more than “add fibre.” The goal is soluble, fermentable fibre that bacteria can actually use: oats, small amounts of psyllium, ground flaxseed, cooked legumes. Introduce one food at a time and build over roughly four weeks. Moving faster usually produces bloating and a child who refuses to eat.
Two green kiwi fruit a day has good trial evidence for softer stools, and children generally tolerate it well. If they will not eat kiwi whole, blend it skin and all into a smoothie. Prunes or figs work too; start with one.
Two cautions. Wheat bran can worsen things in a withholding child. And fibre without adequate fluid produces drier stools, so water intake matters as much as the fibre itself. Magnesium and other nutrients I assess individually in consultation.
3. Retrain the signal
The bowel naturally wants to move 15 to 30 minutes after a meal. Use that window: five minutes sitting on the toilet after breakfast and dinner, which fit most easily into a school-week routine. Feet on a footstool, knees above hips. No pressure to produce anything. It is a sit, not a performance.
At home and at school, if soiling happens, the response should be neutral: a change of clothes, no commentary.
When to seek help promptly
See a practitioner without delay if there is blood in the stool, weight loss, vomiting, soiling that has been present since birth, or constipation that began in the first month of life.
References-
1. Most soiling is retentive overflow (80–90%)
- Rajindrajith S, Devanarayana NM, Benninga MA. “Review article: faecal incontinence in children: epidemiology, pathophysiology, clinical evaluation and management.” Aliment Pharmacol Ther 2013;37:37–48. Reports roughly 80% of childhood faecal incontinence is constipation-associated.
- Loening-Baucke V. “Encopresis and soiling.” Pediatr Clin North Am 1996;43:279–298. Classic review; retentive encopresis in the large majority.
- Tabbers MM, et al. (NASPGHAN/ESPGHAN). “Evaluation and treatment of functional constipation in infants and children.” J Pediatr Gastroenterol Nutr 2014;58:258–274. The main clinical guideline; useful to cite for several points below.
2. Rectal stretching and loss of sensation
- Loening-Baucke V. “Sensitivity of the sigmoid colon and rectum in children treated for chronic constipation.” J Pediatr Gastroenterol Nutr 1984;3:454–459. Shows raised rectal sensory thresholds in constipated children.
- Benninga MA, et al. “Defaecation disorders in children, colonic transit time versus the Barostat.” Gut 2001 (and related Benninga rectal compliance work). Supports increased rectal compliance/megarectum in chronic constipation.
3. Painful bowel motion as the usual trigger
- Borowitz SM, Cox DJ, Tam A, et al. “Precipitants of constipation during early childhood.” J Am Board Fam Pract 2003;16:213–218. Painful defecation was the most common identified precipitant; toilet training and school entry also feature.
- Partin JC, et al. “Painful defecation and fecal soiling in children.” Pediatrics 1992;89:1007–1009. Early paper linking painful stools to later soiling.
4. Microbiome changes in constipated children
- Zoppi G, et al. “The intestinal ecosystem in chronic functional constipation.” Acta Paediatr 1998;87:836–841. Found lower Bifidobacterium and Lactobacillus in constipated children.
- de Meij TGJ, et al. “Characterization of microbiota in children with chronic functional constipation.” PLoS One 2016;11:e0164731. Confirms altered microbial composition versus healthy controls.
- Zhu L, et al. “Structural changes in the gut microbiome of constipated patients.” Physiol Genomics 2014;46:679–686. Adult data, but supports the “loop” framing.
5. Butyrate and bowel motility
- Hamer HM, et al. “Review article: the role of butyrate on colonic function.” Aliment Pharmacol Ther 2008;27:104–119.
6. Gut serotonin (~90%) and motility
- Gershon MD, Tack J. “The serotonin signaling system: from basic understanding to drug development for functional GI disorders.” Gastroenterology 2007;132:397–414.
- Yano JM, et al. “Indigenous bacteria from the gut microbiota regulate host serotonin biosynthesis.” Cell 2015;161:264–276. Directly supports “the microbiome shapes that signalling.”
7. Probiotics: strain-specific, and L. rhamnosus GG showed no benefit
- Banaszkiewicz A, Szajewska H. “Ineffectiveness of Lactobacillus GG as an adjunct to lactulose for the treatment of constipation in children.” J Pediatr 2005;146:364–369. The key negative trial for the post’s LGG claim.
- Coccorullo P, et al. “Lactobacillus reuteri (DSM 17938) in infants with functional chronic constipation.” J Pediatr 2010;157:598–602. Positive trial for a specific strain.
- Tabbers MM, et al. “Fermented milk containing Bifidobacterium lactis DN-173 010 in childhood constipation.” Pediatrics 2011;127:e1392–e1399.
- Wojtyniak K, Szajewska H. “Systematic review: probiotics for functional constipation in children.” Eur J Pediatr 2017;176:1155–1162. Concludes evidence is strain-dependent and overall modest — supports “a support, not the whole plan.”
8. Maintenance for months, not weeks; relapse when stopped early
- Tabbers 2014 guideline (above). Recommends maintenance for at least two months and continuing until symptom-free for a month, with gradual tapering.
- van Ginkel R, et al. “Childhood constipation: longitudinal follow-up beyond puberty.” Gastroenterology 2003;125:357–363. Shows high relapse rates and that a meaningful proportion still have symptoms years later — supports the long-haul message.
9. Kiwifruit and stool softening
- Chey SW, Chey WD, Jackson K, Eswaran S. “Exploratory comparative effectiveness trial of green kiwifruit, psyllium, or prunes in US patients with chronic constipation.” Am J Gastroenterol 2021;116:1304–1312.
- Chan AOO, et al. “Increasing dietary fiber intake in terms of kiwifruit improves constipation in Chinese patients.” World J Gastroenterol 2007;13:4771–4775.Note: the strongest kiwi trials are in adults. I’d soften the post to “good trial evidence (mostly in adults) for softer stools” unless you locate a paediatric RCT.
10. Fibre, fluid and wheat bran
- Tabbers 2014 notes evidence for extra fibre and fluid in children is limited and recommends normal intake rather than excess; this is a fair citation for the “fibre without fluid” caution and for not relying on fibre alone to clear impaction.
- For wheat bran worsening symptoms, direct paediatric evidence is thin; adult IBS/constipation literature (e.g. Francis CY, Whorwell PJ. “Bran and irritable bowel syndrome: time for reappraisal.” Lancet 1994;344:39–40) is the usual reference. Consider framing it as clinical observation.
11. Toilet sitting after meals and posture
Sikirov D. “Comparison of straining during defecation in three positions.” Dig Dis Sci 2003;48:1201–1205. Supports the footstool/knees-above-hips advice.
Tabbers 2014 recommends scheduled toilet sitting after meals as part of behavioural therapy.