Constipation — Causes, Symptoms & Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

Constipation is defined by the Rome IV criteria as: fewer than 3 spontaneous complete bowel movements per week, combined with straining, lumpy/hard stools, sensation of incomplete evacuation, sensation of anorectal blockage, or manual manoeuvres to facilitate defaecation, occurring in at least 25% of defaecations. It affects approximately 16% of adults globally — rising to 33% in those over 60 — and is the most common digestive complaint presenting to primary care. Constipation is classified as functional (primary idiopathic) or secondary (due to an identifiable cause). Chronic functional constipation may be further categorised as slow-transit constipation (prolonged colonic transit), defaecatory dysfunction (pelvic floor dyssynergia), or normal-transit with altered perception. It significantly impairs quality of life and generates substantial healthcare costs. Chronic constipation is a condition of significant personal and societal impact — beyond physical discomfort, it is associated with substantial healthcare utilisation, reduced quality of life, and significant psychological morbidity, particularly in elderly patients in whom faecal impaction may contribute to acute confusion, urinary retention, and bowel obstruction.

Primary (functional) constipation: inadequate dietary fibre intake, dehydration, sedentary lifestyle, suppressing the urge to defaecate, and psychological factors (stress, anxiety). Pelvic floor dyssynergia — paradoxical contraction of the puborectalis and external anal sphincter during defaecation — causes obstructed defaecation despite normal transit. Secondary causes: medications are the most common identifiable cause (opioid-induced constipation — OIC, affecting 60–80% of chronic opioid users; anticholinergics, tricyclics, iron supplements, calcium channel blockers); hypothyroidism; diabetes with autonomic neuropathy; hypercalcaemia; Parkinson's disease; spinal cord injury; Hirschsprung's disease (in children — aganglionosis); colorectal cancer (especially right-sided) causing obstructive symptoms. Risk factors: female sex, advanced age, low socioeconomic status, low fibre diet, insufficient fluid intake, immobility, and depression.

Core symptoms (Rome IV): infrequent bowel movements (<3/week), excessive straining (>25% of defaecations), hard or lumpy stools (Bristol Stool Scale types 1–2), sensation of incomplete evacuation, sensation of anorectal obstruction, and need for digital manoeuvres or perineal support. Associated symptoms: abdominal bloating and distension, crampy lower abdominal discomfort relieved by defaecation, nausea, and fatigue. Complications of severe/chronic constipation: haemorrhoids, anal fissures (severe pain on defaecation with fresh blood), rectal prolapse, faecal impaction (hard mass in rectum, paradoxical overflow diarrhoea in elderly), and large bowel obstruction (faecal impaction causing colonic dilatation — acute complication). Red flag symptoms requiring urgent investigation: rectal bleeding, significant unintentional weight loss, iron deficiency anaemia, palpable abdominal mass, or new constipation after age 50 — all need urgent colorectal cancer exclusion.

Diagnosis is primarily clinical based on Rome IV criteria and thorough history. Physical examination: abdominal examination for distension, tenderness, and masses; digital rectal examination (DRE) to assess sphincter tone, stool consistency in the rectum, paradoxical puborectalis contraction, and palpable masses. Investigations are guided by red flags and treatment failure: blood tests — TFTs (hypothyroidism), calcium, glucose, FBC, CRP, iron studies; colonoscopy or CT colonography for red flags or risk of colorectal cancer (all new constipation in adults >50 warrants investigation). Anorectal physiology studies (anorectal manometry, balloon expulsion test) assess pelvic floor dyssynergia in refractory constipation. Colonic transit study (radiopaque marker test or scintigraphy) diagnoses slow-transit constipation. Defaecating proctography (MRI or fluoroscopic) assesses rectal and pelvic floor anatomy.

Lifestyle first: increase dietary fibre to 25–35 g/day through whole grains, vegetables, fruits, and legumes — psyllium husk supplements (ispaghula) are effective bulk-forming agents. Drink 1.5–2 litres of water daily. Increase physical activity. Establish a regular defaecation time (gastrocolic reflex strongest after breakfast). Respond to the urge to defaecate promptly — do not suppress. Use a footstool to adopt a squatting position on the toilet (reduces puborectalis tension). Laxatives: macrogol (polyethylene glycol — osmotic) is first-line pharmacological treatment — safe for long-term use; lactulose (osmotic — less effective, more bloating); bisacodyl or senna (stimulant — short-term for acute constipation); suppositories and enemas for faecal impaction. Prucalopride (selective 5-HT4 agonist) is approved for chronic constipation unresponsive to laxatives — improves colonic motility significantly. Linaclotide (guanylate cyclase-C agonist) is approved for chronic idiopathic constipation and constipation-predominant IBS. Opioid-induced constipation: methylnaltrexone or naloxegol (peripherally-acting mu-opioid receptor antagonists — PAMORAs) specifically target OIC. Biofeedback therapy is first-line for pelvic floor dyssynergia — teaches correct relaxation of the puborectalis muscle. Surgical (colectomy) is a last resort for severe refractory slow-transit constipation.

Chronic constipation causes a range of local and systemic complications that significantly affect quality of life. Haemorrhoids (piles): straining at stool increases venous pressure in the haemorrhoidal plexus — internal haemorrhoids cause painless bright red rectal bleeding; external haemorrhoids cause perianal pain and swelling. Anal fissure: hard stool tears the anoderm causing severe pain on defaecation, fresh bleeding, and anal sphincter spasm — acute fissures are treated with topical glyceryl trinitrate (GTN 0.4%) or diltiazem; chronic fissures may require botulinum toxin injection or lateral internal sphincterotomy. Rectal prolapse: excessive straining causes the rectal wall to prolapse through the anus — more common in elderly women with pelvic floor weakness. Faecal impaction: a hard mass of stool becomes lodged in the rectum — paradoxical overflow diarrhoea (liquid stool seeping past the impaction) in elderly patients is frequently misdiagnosed as infective diarrhoea and treated with antidiarrhoeals, worsening the impaction. Colonic dilatation: acute colonic pseudo-obstruction (Ogilvie's syndrome — massive dilatation of the colon without mechanical obstruction) or faecal impaction causing bowel obstruction may require urgent decompression or manual disimpaction. Urinary complications: severe constipation, particularly in children, can cause urinary frequency, urgency, and urinary tract infections from bladder compression and incomplete bladder emptying — treatment of constipation resolves urinary symptoms in many children.

Consume 25–35 g of dietary fibre daily — introduce gradually to avoid bloating. Drink at least 1.5–2 litres of fluids daily (mainly water — herbal teas and diluted juices count). Exercise regularly — 30 minutes of moderate activity most days stimulates colonic motility. Respond to the urge to defaecate immediately rather than postponing. Establish a consistent defaecation routine — sitting on the toilet after breakfast takes advantage of the gastrocolic reflex. Limit processed foods, red meat, and refined carbohydrates which slow gut transit. Minimise laxative dependence — regular stimulant laxative use can cause laxative dependency. Review all medications regularly with your doctor for constipating agents — opioid dose reduction, switching anticholinergic medications, and dose adjustments may help.

Go to the emergency department if you have not passed stool or gas for several days with progressive abdominal distension, vomiting, or severe pain — this may indicate bowel obstruction. See your doctor promptly for any of these red flag symptoms: blood in the stool (rectal bleeding) or black tarry stools; unexplained weight loss of more than 3 kg; new constipation in adults over 50 (especially without a clear dietary or medication cause); iron deficiency anaemia; a palpable abdominal or rectal mass; or constipation alternating with diarrhoea. Chronic constipation not responding to lifestyle changes and over-the-counter laxatives after 4–6 weeks also warrants a GP review to exclude secondary causes and consider specialist referral.