Constipation in adults: causes, warning signs and what helps

People use the word to mean different things, and clinicians have to find out which one you mean. For some, it is infrequent stools. For others, it is the effort and discomfort of passing a stool, or the sense that the bowel has not emptied. NICE CKS defines it as a symptom-based condition: bowel movements that are unsatisfactory because they are infrequent, hard to pass or leave a feeling of incomplete emptying.

The NHS description is practical. You are likely to be constipated if you have gone fewer than 3 times in the last week or less often than your own normal, if the poo is unusually large or small and dry, hard or lumpy, if you are straining or in pain, or if you feel you have not fully emptied your bowels. A stomach ache, bloating and nausea may come with it.

Duration matters too. CKS uses the term chronic constipation for symptoms that have been present for at least three months, and secondary constipation for constipation caused by a medicine or an underlying medical condition, as opposed to functional constipation with no known cause.

The NHS lists the most common causes of adult constipation, and for most people one or two of them apply together.

• Not eating enough fibre, which comes from fruit, vegetables and cereals.

• Not drinking enough fluids.

• Moving too little, or spending long periods sitting or lying down.

• Ignoring the urge to go to the toilet, often because of inconvenient or unsuitable facilities.

• A change in diet or daily routine, such as travelling or shift work.

• A side effect of medicine, with opioid painkillers a well-known example.

• Stress, anxiety or depression.

• Pregnancy and the months after birth, and age over 65, when constipation becomes more frequent.

The NHS adds that constipation can be caused by a medical condition such as diverticular disease or bowel cancer, but that this is rare. CKS divides secondary causes into drugs and diseases. An underactive thyroid is a typical example: the NHS lists constipation among its symptoms, along with tiredness, feeling cold, weight gain, low mood and dry skin, and a GP can check thyroid function by blood test.

Irritable bowel syndrome can present with constipation alternating with diarrhoea, and the NHS describes stomach pain or cramps that are usually worse after eating and better after a poo. Pelvic floor problems that interfere with emptying are another possibility, and CKS notes that straining with a feeling of incomplete evacuation may suggest a defecatory disorder such as pelvic floor dyssynergia. The CKS assessment also asks about anxiety, depression, cognitive impairment and eating disorders, which is why a doctor looks at the whole picture and not just the bowels.

The NHS tells people to see a GP if constipation is not getting better with treatment, is regular, or comes with any of the features below. CKS lists red flags that suggest a serious underlying cause such as colorectal cancer. Constipation itself is rarely an emergency, but the combination of severe pain, vomiting and being unable to pass wind or stool may point to a blockage and needs urgent hospital assessment, as the NHS stomach ache advice indicates for those who cannot poo or fart.

• A sudden change in bowel habit that is not explained by diet or medicine.

• Blood in your poo, or bleeding from the bottom; the NHS says black or dark red poo needs an urgent GP appointment or NHS 111.

• Losing weight without trying.

• Regular bloating, tummy pain, or a lump in the tummy.

• Feeling tired all the time, which can be a sign of anaemia.

• Constipation caused by a medicine you have been prescribed, such as an opioid painkiller; do not stop the medicine before speaking to the GP.

• Diarrhoea leaking around hard stool, which can indicate faecal impaction.

• Call 999 or go to A&E if you have a stomach ache with severe pain, or you cannot poo or fart, as the NHS stomach ache advice states.

CKS describes a structured assessment. The clinician asks what you mean by constipation, how long it has lasted, how often you go, what the stools look like (the Bristol Stool Chart can help describe them), whether you strain or feel blocked, and whether there is bleeding, pain, nausea, vomiting or weight loss. They ask about diet, fluids, activity, toileting habits and privacy, mood, medicines, any family history of bowel cancer or inflammatory bowel disease, and what you have already tried.

Examination includes the tummy, to look for tenderness, swelling or a mass, and often a rectal examination to check for fissures, piles, a prolapse, stool that has built up and how well the sphincter works. CKS stresses that in a person with functional constipation and no suspected underlying cause, no investigations are usually required.

When red flags or persisting symptoms warrant it, CKS suggests blood tests to exclude an underlying cause, and an assessment for a defecatory disorder. The NHS bowel cancer page describes a faecal immunochemical test as a way of checking for blood in the stool, and urgent referral for scopes or scans if cancer is suspected. Colonoscopy, CT colonography or barium studies may be arranged by a specialist.

Referral to a gastroenterologist or colorectal surgeon is advised by CKS if a serious cause is suspected, if a secondary cause is suspected that cannot be managed in primary care, or if symptoms persist despite good primary care management.

The NHS recommends a healthy balanced diet that includes fruits containing sorbitol, such as apples, apricots, grapes, raspberries and strawberries, plenty of water and other fluids, avoiding alcohol, and gradually increasing fibre by adding wheat bran, oats or linseed. A regular time and place for the toilet, giving yourself plenty of time and not delaying when the urge comes help, as does resting your feet on a low stool with your knees above your hips. A daily walk or run may help. The NHS says you may notice a difference within a few days, though it can take a few weeks.

If these steps do not work, the NHS suggests speaking to a pharmacist about a suitable laxative, noting that most laxatives work within 3 days and should only be used for a short time. CKS describes a stepped approach in people who need regular treatment: bulk-forming laxatives first, then an osmotic or stool-softening laxative, then a stimulant laxative if needed, with doses adjusted gradually to produce soft, formed stools without straining at least three times per week.

Long-standing constipation can lead to faecal impaction, where stool builds up in the rectum and diarrhoea leaks around it. The NHS says treatment can include stronger prescribed laxatives, a suppository, a mini enema or removal of stool by a healthcare professional.