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Last updated on May 12, 2023

Constipation is a condition that is difficult to define and is often self-diagnosed by patients. Generally, it is characterised by the passage of hard, dry stools less frequently than by the person’s normal pattern. It is important for the pharmacist to find out what the patient means by constipation and to establish what (if any) change in bowel habit has occurred and over what period of time.

ConstipationWhat you need to know

Details of bowel habit, Frequency and nature of bowel actions now

  • When was the last bowel movement?
  • What is the usual bowel habit?
  • When did the problem start? Is there a previous history?

Associated symptoms

  • Abdominal pain/discomfort/bloating/distension
  • Nausea and vomiting
  • Blood in the stool


Any recent change in diet?

Is the usual diet rich in fibre?


Present medication

Any recent change in medication

Previous use of laxatives

Significance of questions and answers

Details of bowel habit

Many people believe that a daily bowel movement is necessary for good health and laxatives are often taken and abused as a result. In fact, the normal range may vary from three movements in 1 day to three in 1 week. Therefore an important health education role for the pharmacist is in reassuring patients that their frequency of bowel movement is normal. Patients who are constipated will usually complain of hard stools which are difficult to pass and less frequent than usual.

The determination of any change in bowel habit is essential, particularly any prolonged change. A sudden change, which has lasted for 2 weeks or longer, would be an indication for referral.

Associated symptoms

Constipation is often associated with abdominal discomfort, bloating and nausea. In some cases constipation can be so severe as to obstruct the bowel. This obstruction or blockage usually becomes evident by causing colicky abdominal pain, abdominal distension and vomiting. When symptoms suggestive of obstruction are present, urgent referral is necessary as hospital admission is the usual course of action. Constipation is only one of many possible causes of obstruction. Other causes such as bowel tumours or twisted bowels (volvulus) require urgent surgical intervention.

Blood in the stool

The presence of blood in the stool can be associated with constipation and, although alarming, is not necessarily serious. In such situations blood may arise from piles (hemorrhoids) or a small crack in the skin on the edge of the anus (anal fissure). Both these conditions are thought to be caused by a diet low in fibre that tends to produce constipation. The bleeding is characteristically noted on toilet paper after defecation. The bright red blood may be present on the surface of the motion (not mixed in with the stool) and splashed around the toilet pan. If piles are present, there is often discomfort on defaecation. The piles may drop down (prolapse) and protrude through the anus. A fissure tends to cause less bleeding but much more severe pain on defecation. Medical referral is advisable as there are other more serious causes of bloody stools, especially where the blood is mixed in with the motion.

Bowel cancer

Large bowel cancer may also present with a persisting change in bowel habit. This condition kills about 16,000 people each year in the UK. Early diagnosis and intervention can dramatically improve the prognosis. The incidence of large bowel cancer rises significantly with age. It is uncommon among people under 50 years. It is more common amongst those living in northern Europe and North America compared with southern Europe and Asia. The average age at diagnosis is 60-65 years.


Insufficient dietary fibre is a common cause of constipation. An impression of the fibre content of the diet can be gained by asking what would normally be eaten during a day, looking particularly for the presence of whole meal cereals, bread, fresh fruit and vegetables. Changes in diet and lifestyle, e.g. following a job change, loss of work, retirement or travel, may result in constipation. An inadequate intake of food and fluids, e.g. in someone who has been ill, may be responsible.

An adequate fluid intake is essential for well-being, and, for both prevention and treatment of constipation. It is thought that an inadequate fluid intake is one of the commonest causes of constipation. Research shows that by increasing fluid intake in someone who is not well hydrated the frequency of bowel actions is increased. It is particularly effective when it is increased alongside an increase in dietary fibre. The recommended daily amount of fluid is 2.5 litres a day for adults and not all of this needs to be in the form of water. Tea and coffee can be counted towards daily fluid intake.


One or more laxatives may have already been taken in an attempt to treat the symptoms. Failure of such medication may indicate that referral to the doctor is the best option. Previous history of the use of laxatives is relevant. Continuous use, especially of stimulant laxatives, can result in a vicious circle where the contents of the gut are expelled, causing a subsequent cessation of bowel actions for 1 or 2 days. This then leads to the false conclusion that constipation has recurred and more laxatives are taken and so on.

Chronic overuse of stimulant laxatives can result in loss of muscular activity in the bowel wall (an atonic colon) and thus further constipation.

Many drugs can induce constipation; some examples are listed in Table. The details of prescribed and over the counter medications being taken should be established.

Table Drugs that may cause constipation


Drug group Drug
Analgesics and opiates Dihydrocodeine, codeine
Antacids Aluminium salts
Anticholinergics Hyoscine
Anticonvulsants Phenytoin
Antidepressants Tricyclics, selective serotonin reuptake inhibitors
Antihistamines Chlorpheniramine, promethazine
Antihypertensives Clonidine, methyldopa
Anti-Parkinson agents Levodopa
Beta-blockers Propranolol
Diuretics Bendroflumethiazide
Laxative abuse  
Monoamine oxidase inhibitors  
Antipsychotics Chlorpromazine


When to refer

  1. Change in bowel habit of 2 weeks or longer
  2. Presence of abdominal pain, vomiting, bloating
  3. Blood in stools
  4. Prescribed medication suspected of causing symptoms
  5. Failure of over the counter medication

Treatment timescale

If 1 week’s use of treatment does not produce relief of symptoms, the patient should see the doctor. If the pharmacist feels that it is necessary to give only dietary advice, then it would be reasonable to leave it for about 2 weeks to see if the symptoms settle.


Constipation that is not caused by serious pathology will usually respond to simple measures, which can be recommended by the pharmacist: increasing the amount of dietary fibre, maintaining fluid consumption and doing regular exercise. In the short term, a laxative may be recommended to ease the immediate problem.

Stimulant laxatives (e.g. sennosides and bisacodyl)

Stimulant laxatives work by increasing peristalsis. All stimulant laxatives can produce griping/cramping pains. It is advisable to start at the lower end of the recommended dosage range, increasing the dose if needed. The intensity of the laxative effect is related to the dose taken. Stimulant laxatives work within 6-12 h when taken orally. They should be used for a maximum of 1 week. Bisacodyl tablets are enteric coated and should be swallowed whole because bisacodyl is irritant to the stomach. If it is given as a suppository, the effect usually occurs within 1 h and sometimes as soon as 15 min after insertion.

Docusate sodium appears to have both stimulant and stool-softening effects and acts within 12 days.

The use of senna pods and cascara, which is non-standardised, should be discouraged because the dose and therefore action are unpredictable. Castor oil is a traditional remedy for constipation, which is no longer recommended since there are better preparations available.

Bulk laxatives (e.g. ispaghula, methylcellulose and sterculia)

Bulk laxatives are those that most closely copy the normal physiological mechanisms involved in bowel evacuation and are considered by many to be the laxatives of choice. Such agents are especially useful where patients cannot or will not increase their intake of dietary fibre. Bulk laxatives work by swelling in the gut and increasing fecal mass so that peristalsis is stimulated. The laxative effect can take several days to develop.

The sodium content of bulk laxatives (as sodium bicarbonate) should be considered in those requiring a restricted sodium intake.

When recommending the use of a bulk laxative, the pharmacist should advise that an increase in fluid intake would be necessary. In the form of granules or powder, the preparation should be mixed with a full glass of liquid (e.g. fruit juice or water) before taking. Fruit juice can mask the bland taste of the preparation. Intestinal obstruction may result from inadequate fluid intake in patients taking bulk laxatives, particularly those whose gut is not functioning properly as a result of abuse of stimulant laxatives.

Osmotic laxatives (e.g. lactulose, Epsom salts and Glauber’s salts)

Lactulose works by maintaining the volume of fluid in the bowel. It may take 1-2 days to work. Lactitol is chemically related to lactulose and is available as sachets. The contents of the sachet are sprinkled on food or taken with liquid. One or two glasses of fluid should be taken with the daily dose. Lactulose and lactitol can cause flatulence, cramps and abdominal discomfort.

Epsom salts (magnesium sulphate) is a traditional remedy that, while no longer recommended, is still requested by some older customers. It acts by drawing water into the gut; the increased pressure results in increased intestinal motility. A dose usually produces a bowel movement within a few hours. Repeated use can lead to dehydration.

Glycerin suppositories have both osmotic and irritant effects and usually act within 1 h. They may cause rectal discomfort. Moistening the suppository before use will make insertion easier.

Constipation in children

Parents sometimes ask for laxatives for their children. Fixed ideas about regular bowel habits are often responsible for such requests. Numerous factors can cause constipation in children, including a change in diet and emotional causes. Simple advice about sufficient dietary fibre and fluid intake may be all that is needed. If the problem is of recent origin and there are no significant associated signs, a single glycerin suppository together with dietary advice may be appropriate. Referral to the doctor would be best if these measures are unsuccessful.

Constipation in pregnancy

Constipation commonly occurs during pregnancy; hormonal changes are responsible and it has been estimated that one in three pregnant women suffers from constipation. Dietary advice concerning the intake of plenty of high-fibre foods and fluids can help. Oral iron, often prescribed for pregnant women, may contribute to the problem.

Stimulant laxatives are best avoided during pregnancy; bulk-forming laxatives are preferable, although they may cause some abdominal discomfort to women when used late in pregnancy.

Constipation in the elderly

Constipation is a common problem in elderly patients for several reasons. Elderly patients are less likely to be physically active; they often have poor natural teeth or false teeth and so may avoid high-fibre foods that are more difficult to chew; multidrug regimens are more likely in elderly patients, who may therefore suffer from drug-induced constipation; fixed ideas about what constitutes a normal bowel habit are common in older patients. If a bulk laxative is to be recommended for an elderly patient, it is of great importance that the pharmacist give advice about maintaining fluid intake to prevent the possible development of intestinal obstruction.

Laxative abuse

Two groups of patients are likely to abuse laxatives: those with chronic constipation who get into a vicious circle by using stimulant laxatives, which eventually results in damage to the nerve plexus in the colon, and those who take laxatives in the belief that they will control weight, e.g. those who are dieting or, more seriously, women with eating disorders (anorexia nervosa or bulimia), who take very large quantities of laxatives. The pharmacist is in a position to monitor purchases of laxative products and counsel patients as appropriate. Any patient who is ingesting large amounts of laxative agents should be referred to the doctor.

Constipation in practice

Case 1

Mr Johnson is a middle-aged man who occasionally visits your pharmacy. Today he complains of constipation, which he has had for several weeks. He has been having a bowel movement every few days; normally they are every day or every other day. His motions are hard and painful to pass. He has not tried any medicines as he thought the problem would go of its own accord. He has never had problems with constipation in the past. He has been taking atenolol tablets 50 mg once a day, for over 1 year.

He does not have any other symptoms, except a slight feeling of abdominal discomfort. You ask him about his diet; he tells you that since he was made redundant from his job at a local factory 3 months ago, he has tended to eat less than usual; his dietary intake sounds as if it is low in fibre. He tells you that he has been applying for jobs, with no success so far. He says he feels really down and is starting to think that he may never get another job.

The pharmacist’s view

Mr Johnson’s symptoms are almost certainly due to the change in his lifestyle and eating pattern. Now that he is not working he is likely to be less physically active and his eating pattern has probably changed. From what he has said, it sounds as if he is becoming depressed because of his lack of success in finding work. Constipation seems to be associated with depression, separately from the constipating effect of some antidepressant drugs.

It would be worth asking Mr Johnson if he is sleeping well (signs of clinical depression include disturbed sleep: either difficulty in getting to sleep or difficulty in waking early and not being able to get back to sleep). Weight can change either way in depression. Some patients eat for comfort, while others find their appetite is reduced. Depending on his response, you might consider whether referral to his doctor is needed.

To address the dietary problems, he could be advised to start the day with a wholegrain cereal and to eat at least four slices of wholemeal bread each day. Baked beans are a cheap, good source of fibre. Fresh vegetables are also fibre rich. It would be important to stress that fluid intake should also be increased. A high-fibre diet means patients should increase their fibre intake until they pass one large, soft stool each day; the amount of fibre needed to produce this effect will vary markedly between patients. The introduction of dietary fibre should be gradual; too rapid an increase can cause griping and wind. Mr Johnson also needs to make sure he is drinking the recommended daily fluid intake of 2.5 litres each day.

To provide relief from the discomfort, a suppository of glycerin or bisacodyl could be recommended to produce a bowel evacuation quickly; in the longer term, dietary changes provide the key. He should see the doctor if the suppository does not produce an effect; if it works but the dietary changes have not been effective after 2 weeks, he should go to his doctor. Mr Johnson’s medication is unlikely to be responsible for his constipation because, although beta-blockers can sometimes cause constipation, he has been taking the drug for over 1 year with no previous problems.

The doctor’s view

ConstipationThe advice given by the pharmacist is sensible. It is likely that Mr Johnson’s physical and mental health have been affected by the impact of a significant change in his life. The loss of his job and the uncertainty of future employment is a major and continuing source of stress. The fact that the pharmacist has taken time to check out how he has been affected will in itself be therapeutic. It also gives the pharmacist the opportunity to refer to the doctor if necessary. Many people are reluctant to take such problems to their doctor but a recommendation from the pharmacist might make the process easier. Hopefully, the advice given for constipation will at least improve one aspect of his life. If the constipation does not resolve within 2 weeks, Mr Johnson should see his doctor.

Case 2

Your counter assistant asks if you will have a word with a young woman who is in the shop. She was recognised by your assistant as a regular purchaser of stimulant laxatives. You explain to the woman that you will need to ask a few questions because regular use of laxatives may mean an underlying problem, which is not improving. In answer to your questions she tells you that she diets almost constantly and always suffers from constipation. Her weight appears to be within the range for her height. You show her your pharmacy’s BMI (body mass index) chart and work out with her where she is on the chart, which confirms your initial feeling. However, she is reluctant to accept your advice, saying that she definitely needs to lose some more weight. You ask about her diet and she tells you that she has tried all sorts of approaches, most of which involve eating very little.

The pharmacist’s view

Unfortunately this sort of story is all too common in community pharmacy, with many women who seek to achieve weight below the recommended range. The pharmacist can explain that constipation often occurs during dieting simply because insufficient bulk and fibre is being eaten to allow the gut to work normally. Perhaps the pharmacist might suggest that she joins a local group, either weight watchers or a self-help group. (The local health promotion unit will know what is available.) Despite the pharmacist’s advice, many customers will still wish to purchase laxatives and the pharmacist will need to consider how to handle refusal of sales. Offering stimulant laxatives for sale by self-selection can only exacerbate the problems and make it more difficult to monitor sales and refuse them when necessary.

The doctor’s view

This is obviously a difficult problem for the pharmacist. It is inappropriate for the young woman to continue taking laxatives and she could benefit from counselling. However, a challenge from the pharmacist could result in her simply buying the laxatives elsewhere. If, as is likely, she has an eating disorder, she may have very low self-esteem and be denying her problem. Both these factors make it more difficult for the pharmacist to intervene most effectively. An ideal outcome would be appropriate referral, which would depend on local resources but which might initially be to the doctor.

If she is seen by the doctor, an empathic approach is necessary. The most important thing is to give her full opportunity to say what she thinks about the problem, how it makes her feel and how it affects her life. Establishing a supportive relationship with resultant trust between patient and doctor is the major aim of the initial consultation. Once this has been achieved, further therapeutic opportunities can be discussed and decided on together.

Case 3

A man comes into the pharmacy and asks for some good laxative tablets. Further questioning by the pharmacist reveals that the medicine is for his dad who is aged 72 years. He does not know many details except that his dad has been complaining of increasing constipation over the last 2-3 months and has tried senna tablets without any benefit.

The pharmacist’s view

Third-party or proxy consultations are often challenging because the person making the request may not have all of the relevant information. However, in this case the decision is quite clear. The patient needs to be referred to the doctor because of the long history of the complaint and the unsuccessful use of a stimulant laxative.

The doctor’s view

Referral to the general practitioner should be recommended in this situation. A glycerin suppository is a safe treatment to use in the meantime. Clearly, more information is needed to make an opinion and diagnosis. A prolonged and progressive change in bowel habit is an indication for referral to hospital for further investigations as the father could have a large bowel cancer. The general practitioner would need to gather more information about his symptoms and would perform an examination that would include abdominal palpation and a digital rectal examination.

This latter examination could confirm the presence of a rectal tumour. It is likely that an urgent referral would then be made for further investigations as an outpatient. At hospital the investigations could include sigmoidoscopy plus a barium enema X-ray and/or a colonoscopy. In colonoscopy a flexible fibre-optic tube is passed through the anus and then up and around the whole of the large bowel to the caecum.

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