Constipation Management in Adults
On this page
Direct answer
Two or more of six Rome IV criteria for three months — fewer than three spontaneous bowel motions a week, straining, lumpy or hard stools, a sense of incomplete evacuation or anorectal obstruction, manual manoeuvres needed, with insufficient criteria for IBS — defines functional constipation once secondary causes are excluded. That exclusion is the clinical heart: hypothyroidism, hypercalcaemia, diabetes with autonomic neuropathy, Parkinson disease, opiate analgesia, iron supplements, anticholinergics and calcium-channel blockers, plus mechanical causes from colon cancer, all need consideration in new-onset or late-onset constipation. Treatment is fibre (25-30 g/day) with adequate fluid, then osmotic laxatives — polyethylene glycol is the evidence favourite — then stimulant laxatives judiciously, with prescription secretagogues (lubiprostone, linaclotide) and prucalopride for refractory cases, and biofeedback as the specific therapy for dyssynergic defaecation confirmed by anorectal manometry.
What you must remember
- Rome IV six criteria: fewer than three spontaneous stools per week, straining more than a quarter of the time, lumpy or hard stools, sensation of incomplete evacuation, sensation of anorectal obstruction, manual manoeuvres to facilitate — two or more for three months with onset six months prior.
- Alarm pivot to colonoscopy: new constipation after age 45-50, rectal bleeding, unexplained weight loss, iron-deficiency anaemia, strong family history of colorectal cancer, or a sudden change in bowel habit — never reflexively treated as functional.
- Secondary causes checklist: hypothyroidism (TSH), hypercalcaemia (serum calcium), diabetes, Parkinson disease and spinal disease, pregnancy, and drugs — opioids, iron, anticholinergics, verapamil, ondansetron, aluminium antacids.
- Laxative classes with mechanisms: bulk (ispaghula, bran — needs fluid), osmotic (polyethylene glycol first-line, lactulose, magnesium hydroxide), stool softeners (docusate — weak), stimulants (senna, bisacodyl, sodium picosulfate — enteric plexus), secretagogues (lubiprostone chloride-channel, linaclotide guanylate-cyclase), 5-HT4 agonist prucalopride 1-2 mg daily.
- Opioid-induced constipation specifically: scheduled osmotic plus stimulant laxatives from the first opioid prescription; peripherally acting mu-receptor antagonists (methylnaltrexone, naloxegol, naldemedine) when standard laxatives fail — they reverse gut motility without analgesia.
- Dyssynergic defaecation: paradoxical contraction or failed relaxation of the puborectalis and external anal sphincter on attempted defaecation; diagnosed with anorectal manometry, balloon expulsion test and defecography; biofeedback is the treatment of choice, not laxatives.
- Slow-transit constipation: colonic transit study (radiopaque markers or wireless motility capsule) after laxative washout; subtotal colectomy is a last resort for refractory cases with proven pan-colonic delay and preserved pelvic floor function.
- Indian practice point: Indian diets are often fibre-rich yet constipation remains common because of low fluid intake, sedentary habits and rising opioid and anticholinergic prescriptions in the elderly — address fluids before escalating drugs.
Triage of the constipated adult
A 52-year-old woman reports a decade of infrequent, hard stools with straining and incomplete evacuation, no bleeding, stable weight, normal haemoglobin and a normal examination including rectal examination. She meets Rome IV criteria; hypothyroidism and hypercalcaemia are excluded with TSH and calcium, and her drug list holds no culprit. First-line care is structured: 25-30 g of daily fibre with at least 1.5-2 L of fluid, ispaghula supplemented, response assessed at four weeks. She returns only marginally better, so polyethylene glycol is added — the osmotic with the best evidence and the least bloating — and a stimulant such as senna at night for rescue. Still incomplete evacuation dominates her account, and the classic clue appears: she supports her perineum or digitally evacuates; anorectal manometry with a balloon expulsion test confirms dyssynergic defaecation, and biofeedback retraining — practiced weekly over six to eight sessions — resolves more than laxatives ever did.
The contrast case is her 58-year-old brother, whose lifelong habit changed over two months with pencil-thin stools and 5 kg loss: he goes for colonoscopy before any laxative conversation, because his constipation is a symptom of a left colon cancer until excluded.
Viva favourites
Examiners probe three edges. First, "which laxative for which patient" — polyethylene glycol for evidence-based first-line, lactulose acceptable but bloating-prone, magnesium for rapid need in renal-normal patients (avoided in renal failure), stimulants for short courses rather than the old fear of permanent damage (modern data do not support "cathartic colon" for senna). Second, the pelvic floor: any story of prolonged digits-in-the-vault evacuation, straining with a sense of blockage, or failed laxative trials earns manometry, and the answer to "treatment of dyssynergic defaecation" is biofeedback, full stop. Third, opioid-induced constipation — the prescribing of a stimulant-plus-osmotic combination at the start of opioid therapy, and methylnaltrexone as the reversal agent when refractory; forgetting naloxegol's shared indication with it loses easy marks.
Frequently asked questions
What are the Rome IV criteria for functional constipation?
Two or more of six features for three months — under three spontaneous stools a week, straining, lumpy hard stools, incomplete evacuation, anorectal obstruction sensation, or manual manoeuvres — with symptom onset at least six months earlier and insufficient criteria for IBS.
Which laxative has the best evidence for chronic constipation?
Polyethylene glycol — an isotonic osmotic agent effective and safe for long-term use, ahead of lactulose, which ferments and bloats; stimulants are reserved for shorter or rescue use.
How is dyssynergic defaecation diagnosed and treated?
By anorectal manometry with balloon expulsion (and defecography when needed), showing paradoxical or non-relaxing pelvic floor contraction; biofeedback retraining is the specific, superior therapy.
Which drugs most commonly cause constipation?
Opioids, iron supplements, anticholinergics (including tricyclics and some antipsychotics), verapamil, ondansetron and aluminium-containing antacids — always reconcile the list before labelling constipation functional.
What is the specific therapy for opioid-induced constipation refractory to laxatives?
A peripherally acting mu-opioid receptor antagonist — methylnaltrexone, naloxegol or naldemedine — which restores gut motility without reversing systemic analgesia.