Constipation in Childhood

Definition: difficulty passing stools — infrequent (≤2/week), painful, or associated with stool retention. The Rome IV criteria formalise this: functional constipation is diagnosed when a child meets two or more of the following for at least a month — two or fewer defecations per week; at least one episode of faecal incontinence per week; a history of retentive posturing or excessive volitional stool retention; a history of painful or hard bowel movements; a large faecal mass in the rectum; or a history of large-diameter stools that may obstruct the toilet — with insufficient criteria to diagnose irritable bowel syndrome.

Epidemiology: affects 5–30% of children worldwide and is responsible for around 3% of general-practice paediatric visits. Median onset is age 2–3 years, but constipation can arise at any transitional phase (starting solids, toilet training, starting school). Most is functional/behavioural — organic pathology is rare, accounting for no more than about 5% of cases.

Organic causes to exclude

A minority of presentations have an identifiable organic cause — always consider these alongside functional constipation, especially with a red flag below:

• Allergy — cow’s milk protein intolerance and/or other food protein intolerances
• Coeliac disease
• Hypothyroidism
• Cystic fibrosis
• Electrolyte abnormalities — hypercalcaemia, hyperkalaemia
• Drugs — opiates, phenobarbital, anticholinergics
• Neuropathic disorders — Hirschsprung disease, internal sphincter achalasia
• Spinal cord abnormalities — myelomeningocele, tethered spinal cord, syringomyelia (stooling may occur without sensation or urge)
• Anatomic malformations — imperforate anus, anteriorly displaced anus

Red flags (RACGP)

• No meconium passed in the first 48 hours of life → congenital/mechanical obstruction (e.g. Hirschsprung disease)
• Constipation from birth → congenital/mechanical obstruction
• Bloody diarrhoea → infection, IBD, cow’s milk allergy
• Spaghetti/ribbon stools (child <1 year) → anorectal stricture/stenosis
• Failure to thrive/growth failure
• Leg weakness or delayed gross motor development → spinal pathology
• Abdominal distension with vomiting/fever/rash
• Abnormal appearance, position or patency of the anus
• Perianal disease, or extra-intestinal features suggestive of IBD (rashes, arthritis, red/sore eyes, mouth ulcers)
• Urinary symptoms, abnormal lower-limb neurology, a patulous anus, or absent perineal sensation
• Onset of constipation before one month of age

History (RACGP)

≤2 stools/week; excessive stool retention; painful or hard bowel movements (→ avoidance behaviour from fear of pain); a palpable large faecal mass reported (do not routinely perform a DRE on children — refer to a specialist); large-diameter, bulky stools; stool consistency per the Bristol Stool Chart (normal = 3–4); >1 episode/week of faecal incontinence after toilet training is complete. Low fibre/fluid intake is rarely the primary cause, but can contribute. Ask about anticholinergic use and any prior laxative use/response.

Withholding behaviours are a common, easily-missed sign: going stiff, clenching the buttocks, walking on tiptoes, crossing the legs, bracing against furniture, an all-fours or curled-up posture, or standing rigidly with legs straight.

Consider cow’s milk protein intolerance, particularly for infants: ask about onset relative to a change from breast to formula feeding, starting cow’s milk, or introducing solids, and about atopic disease (eczema, asthma, rhinitis) or a family history of atopy/food intolerance. Allergy (IgE) testing is not recommended to diagnose it, since milk-associated constipation is usually not IgE-mediated.

Examination

Growth parameters (height, weight, head circumference) — a faltering trajectory suggests failure to thrive. Abdominal exam for distension, bowel sounds, palpable stool. Assess gait, lower-limb tone, power, reflexes and plantar responses — abnormal findings raise suspicion of an occult spinal cord lesion. Spine/sacrum exam for scoliosis, hair patches or sacral pits (spina bifida). DRE is not routine — specialist input only. Check for anal fissures and treat if present (barrier creams).

Investigations

Not required if the history is consistent with functional constipation. For intractable constipation, consider FBC, TFTs, calcium/phosphate/ magnesium, and coeliac serology (IgA, tissue transglutaminase IgA) if there is poor growth, iron-deficiency anaemia, or onset around the introduction of gluten. AXR is not routinely recommended and doesn’t help diagnose idiopathic/functional constipation — reserve for suspected bowel obstruction (via ED). MRI of the spine is not required in the primary-care setting for a child without neurological red flags.

Diet

Normal fibre intake, fluid intake and exercise are recommended for children with constipation — fibre supplements are not routinely recommended. Infants taking large volumes of formula may benefit from a reduced intake. For intractable constipation with a suspected cow’s milk protein contribution, a one-month trial of avoiding cow’s milk and soy protein can be considered, with calcium supplementation (or almond/rice alternatives) during the trial; dairy can be re-trialled every 6–12 months as tolerated. Where a child is reluctant to eat fibre-rich foods, or withholds defecation at school, simple, practical adjustments — earlier breakfast to allow time to open the bowels before leaving home, involving the whole family in dietary change — can help without escalating to a formal exclusion diet.

Treatment

Refer all non-functional causes to a specialist, especially with red flags present. For functional constipation in children >1 year:

Toileting behaviour and education

The main treatment — laxatives are an adjunct to ease stool passage, not a substitute for this.

• Reassure parents.
• Toilet timing: sit on the toilet for 5 minutes after each meal, 3× daily (uses the gastrocolic reflex).
• Star chart/stool diary to make it a positive, trackable experience — coordinate with school if needed.
• Optimal positioning: knees above hip level, straight back.
• For a child not yet toilet-trained for stool, continue using nappies while laxatives soften the stool and the child regains confidence — toilet training itself should be child-led, not forced alongside disimpaction.

Laxatives

A 2016 Cochrane review of 25 randomised trials (2,310 children) found osmotic laxatives — polyethylene glycol (PEG) preparations — increase the frequency of bowel movements in constipated children, with generally low rates of minor side effects; liquid paraffin (mineral oil) also increased bowel-movement frequency, though most trials were small and of poor or unclear quality; there was no evidence that lactulose is superior to the other agents studied, although no trial has compared it directly with placebo. PEG remains first-line.

All laxatives can cause abdominal discomfort — don’t stop abruptly, wean gradually. Titrate the dose until stools are the consistency of “wet cement/porridge”, then reduce to 1 soft, formed stool per day (Bristol 3–4) or a minimum of 3 stools/week with no pain or soiling.

If <12 months old, use lactulose (Actilax) 5 mL/day. Otherwise start macrogol per the table below, titrating to 1–2 soft bowel actions/day (don’t adjust dose more often than every 3–4 days).

Medication	Dosage	Practical notes
Movicol (macrogol 3350 + electrolytes)	Movicol-Half/Junior: 1–6 yrs — 1 sachet (up to 4/day); 6–12 yrs — 2 sachets (up to 4/day). Full-strength: >12 yrs — 1–4 sachets/day	Dissolve in half a cup of liquid (quarter cup for half-strength/Junior); colder is more palatable. May cause cramps/diarrhoea. PBS-listed, no authority required.
OsmoLax / ClearLax (macrogol 3350, no electrolytes)	2–6 yrs — 1 small scoop/day; 6–12 yrs — 1 large scoop/day; >12 yrs — 1–2 large scoops/day	Large scoop 17 g / small scoop 8.5 g; mix with a cup (or half cup) of liquid. Same active ingredient as Movicol without the salty taste. May cause cramps/diarrhoea. PBS-listed, no authority required.
Actilax (lactulose)	1–12 months — 3–5 mL/day; 1–5 yrs — 5–10 mL/day; 5–14 yrs — 10–40 mL/day	Split larger doses twice daily; mix with water, milk or juice. Can cause bloating/discomfort.

An alternative, weight-based PEG regimen (ESPGHAN/NASPGHAN, as summarised in AJGP 2018) is sometimes used instead of the fixed age-band sachet doses above, particularly for disimpaction: 1–1.5 g/kg/day for 3–6 days, then a maintenance dose of 0.75 g/kg/day. Either approach is reasonable — titrate to stool consistency rather than switching regimens mid-course. Weight-based PEG dosing sourced from AJGP, not Australian Prescriber — cross-check against current eTG/AMH before prescribing.

Stimulant laxatives (second-line/add-on)

Add a stimulant laxative if PEG/macrogol alone hasn’t achieved adequate disimpaction after two weeks, or for a brief breakthrough episode of constipation on otherwise-adequate softener treatment.

Medication	Dosage
Senna	2–6 yrs: 2.5–7.5 mL/day; 6–12 yrs: 5–15 mL/day (syrup 7.5 g/5 mL)
Bisacodyl	4–18 yrs: 5–20 mg/day oral; 2–18 yrs: 5–10 mg rectally once daily
Sodium picosulfate	1 month–4 yrs: 2.5–10 mg/day; 4–18 yrs: 2.5–20 mg once daily

Avoid stimulant laxatives where there is a megarectum impacted with hard stool — they can worsen overflow faecal incontinence and abdominal pain; docusate (a stimulant with stool-softening properties) is a reasonable alternative in that situation. Doses sourced from AJGP, not Australian Prescriber — cross-check against current eTG/AMH before prescribing.

Disimpaction

Often the necessary first step when there’s chronic constipation with overflow soiling and faecal loading on exam.

• Warn the family to expect a large stool (“faecaloma”) followed by loose stools.
• Use polyethylene glycol 3350 (PEG) ± electrolytes.
• Consider keeping school-aged children home during the clean-out period; seek medical advice if the child becomes unwell.

Clean-out dosing (Movicol full-strength sachets/day), review at 2–4 days:

Age	Day 1	Day 2	Day 3	Day 4	Day 5	Day 6	Day 7
1–6 yrs	1	2	2	3	3	4	4
6–12 yrs	2	3	4	5	6	6	6
12+ yrs	8	8	8	—	—	—	—

When to refer

To a paediatrician, if constipation is medication-dependent or medication-resistant after around six months of adequate treatment, if there’s doubt about the diagnosis, or if an organic cause is suspected — further management may include allergy diets, specialist pelvic-floor training, colonic transit studies, anal manometry or rectal biopsy.

To allied health, if additional help with toileting is needed: an occupational therapist or continence physiotherapist for a child with a developmental age over four years, or a nurse-led continence clinic. The Continence Foundation of Australia (continence.org.au) provides family support resources.

Prognosis

Up to 50% of children referred to a paediatrician for constipation regain normal bowel function and are off laxatives within 6–12 months. Early treatment matters: 80% of children treated early in their course recover without laxatives by six-month follow-up, compared with 32% of children whose treatment was delayed.

Follow-up

Regular review (phone is fine) to monitor progress, adjust medication, reinforce education, support the family and check the stool diary. Only wean medication once stools are regular and effortless for at least 6 months for chronic constipation — restart promptly at any sign of relapse. If there’s no response within a month, review adherence first; if adherence is adequate, consider pathological causes and refer. A paediatric physiotherapist (pelvic floor exercises) or nurse-led continence clinic can help.