Constipation is a common gastrointestinal problem characterised by infrequent bowel movements, difficult passage of stool, excessive straining, hard or lumpy stools, or a persistent sensation of incomplete evacuation. There is no single bowel-movement frequency that defines constipation because normal bowel habits vary considerably between individuals. Clinically, chronic constipation is often considered when symptoms persist over an extended period and fulfil established symptom criteria, such as those used for functional gastrointestinal disorders. Constipation can be a temporary consequence of changes in diet, fluid intake, activity or routine, but it can also result from medications, metabolic disorders, neurological disease, structural abnormalities or disorders of intestinal motility.
The formation and passage of stool depend on coordinated movement through the colon, absorption of water, storage in the rectum and appropriately timed relaxation of the pelvic floor and anal sphincters. When colonic transit is slow, excessive water is absorbed and stools can become dry and difficult to pass. Some people have normal or even rapid transit but experience difficulty evacuating because the pelvic-floor muscles do not relax appropriately during defecation; this is sometimes termed a defecatory disorder. Functional constipation can therefore arise from several different physiological mechanisms rather than simply from insufficient fibre or water. Irritable bowel syndrome with constipation differs because recurrent abdominal pain is a defining feature of that disorder.
Common contributors to Constipation include inadequate dietary fibre, insufficient fluid intake, low physical activity, changes in routine and repeated suppression of the urge to defecate. Medications are also important causes, particularly opioid analgesics, some anticholinergic medicines, certain antidepressants, iron supplements, calcium-containing preparations and some drugs used for neurological or cardiovascular conditions. Medical conditions such as hypothyroidism, diabetes, neurological disorders and abnormalities affecting calcium metabolism can contribute. Pregnancy can alter bowel function through hormonal and mechanical effects. Constipation can also occur after surgery or during periods of reduced mobility. Identifying the context is therefore more informative than assuming that one lifestyle factor is responsible.
Management of uncomplicated Constipation usually begins with measures intended to improve stool consistency and bowel transit. Increasing dietary fibre gradually can help some people, particularly when accompanied by adequate fluid intake, although large amounts of fibre can worsen bloating or symptoms in some individuals. Regular physical activity can support normal bowel function, and establishing sufficient time and privacy for toileting can help. When lifestyle measures are insufficient, laxatives can be used according to the underlying problem and clinical circumstances. Bulk-forming agents increase stool bulk, osmotic agents draw water into the bowel, and stimulant agents increase intestinal propulsion. The choice, dose and duration should take account of age, other medicines and the possibility of an underlying medical cause.
Constipation can produce abdominal discomfort, bloating, excessive straining and a feeling that the bowel has not emptied completely. Severe or prolonged constipation can lead to faecal impaction, in which a large mass of hardened stool becomes lodged in the rectum or colon. Overflow diarrhoea can occur when liquid stool passes around impacted stool and may misleadingly appear to indicate diarrhoea rather than severe constipation.
Chronic straining can aggravate haemorrhoids and anal fissures, while persistent symptoms can significantly affect quality of life. In people with limited mobility, neurological disease or impaired cognition, constipation may become particularly troublesome because normal recognition of the urge to defecate or the ability to reach a toilet can be compromised.
Most Constipation is not caused by a dangerous structural disease, but certain features warrant medical assessment. New or persistent constipation in an older adult, unexplained weight loss, rectal bleeding, iron-deficiency anaemia, persistent vomiting, severe abdominal pain, fever, marked abdominal distension or a substantial change in established bowel habit can indicate a condition requiring investigation. Complete inability to pass stool or gas accompanied by severe pain and vomiting can occur with intestinal obstruction and requires urgent assessment. The significance of a symptom depends on age, duration, severity, medications, family history and associated findings, so constipation should not automatically be attributed to lifestyle.
Diagnosis of Constipation is primarily clinical. A clinician may ask about bowel frequency, stool form, straining, urgency, incomplete evacuation, diet, fluid intake, medicines, physical activity and associated symptoms. Examination may include assessment of the abdomen and, when appropriate, a rectal examination. Tests are not routinely required for every uncomplicated case, but blood tests, imaging, endoscopic investigation or specialised bowel-function testing may be appropriate when symptoms are atypical, severe, persistent or associated with warning signs. Colorectal cancer, bowel obstruction, inflammatory disease and endocrine or metabolic disorders are among the conditions that may need consideration depending on the presentation.
Constipation should be distinguished from simply having bowel movements less frequently than another person. Some healthy people naturally defecate several times a day, while others do so only every few days without difficulty. The clinically important issue is the combination of frequency, stool consistency, ease of passage and associated symptoms. Acute constipation may develop over days, whereas chronic constipation can persist for months or longer.
In children, toilet training, diet, behavioural factors and withholding can be particularly important, while older adults may have multiple medication and disease-related contributors. The condition is therefore best understood as a disorder of bowel function with numerous possible mechanisms rather than as a single disease with one universal cause.
