Management of constipation in adults

Constipation is typically defined as bowel motions less than three times a week.²¹¹ In practice constipation is often defined as passage of stools less frequently than the person's normal pattern. Constipation is a common symptom and can be short-term or chronic, if lasting three months or more. Laxatives are commonly prescribed, and this hot topic is to ensure they are prescribed appropriately.

There are some patient groups where symptoms may persist despite lifestyle and medication changes, for example when constipation inducing drugs cannot be stopped or in chronic conditions, e.g. Parkinson’s disease, multiple sclerosis.²¹¹

Laxatives are indicated in relief of faecal impaction, overflow diarrhoea, and where a bowel motion is unlikely to occur without intervention.

Excluded from this hot topic:

• people receiving palliative care
• bowel preparation prior to investigation or surgery
• the management of chronic laxative misuse
• the management of organic causes of secondary constipation

The healthcare professional (HCP) should take a history to assess for potential underlying conditions and consider referral to secondary care where appropriate e.g. pelvic floor dyssynergia, suspected colorectal cancer (urgent referral required).²¹¹

Before starting a laxative, consider other factors which may be contributing to the symptoms (e.g. inadequate fluid intake, lack of physical activity, failure to act on urge).²¹¹ Non-pharmacological interventions should be tried first.

Non–pharmacological interventions (see decision support tools).

First line evidence based advice for constipation should include:

• increasing fibre in the diet
• increasing physical activity
• ensuring adequate fluid intake (1.5-2 litres daily, unless fluid restricted)
• going to the toilet when needing to (“call to stool”)
• good positioning

Medication induced constipation

Many medicines are implicated in inducing constipation, including those with high anticholinergic burden.²¹² Such medication should be reviewed and stopped or reduced where appropriate.²¹¹

Medication that can cause constipation²¹¹

Do not prescribe laxatives if there is suspected:²¹¹

• intestinal obstruction or perforation
• paralytic ileus
• Crohn's disease or ulcerative colitis
• toxic megacolon

Avoid certain laxatives in specific circumstances:

• colonic atony or faecal impaction (bulk-forming laxatives)
• severe dehydration (bisacodyl)
• galactosaemia (lactulose)
• history of hypersensitivity to peanuts (arachis oil enema)

Prescribe laxatives with caution if there is:²¹¹

• a risk of misuse (e.g. in eating disorders) – due to this, there is a limit to the number of stimulant laxative medications that can be bought over the counter
• a risk of electrolyte imbalance, such as hypokalaemia, which can occur with long-term use
• caution with macrogols in
  • cardiovascular disease due to risks of fluid and electrolyte disturbance
  • ischaemic colitis
  • low salt diet – many preparations are considered high in sodium, therefore check individual summary of product characteristics (SPC)
• caution with lactulose in lactose intolerance - may cause diarrhoea
• caution with prucalopride in ischaemic heart disease or arrhythmias
• pregnancy – keep under review to avoid use becoming long-term
• bulk forming laxatives should not be prescribed for patients with opioid induced constipation; suspected faecal impaction nor taken at bedtime

Adverse effects

• laxatives may cause diarrhoea
• other side effects include crampy pain, bloating, flatulence, nausea and vomiting²¹⁴
• macrogols can counteract the effect of starch-based food thickeners by liquifying the starch and therefore eliminating the thickening effect²¹⁵
• prescribers should be aware PEG laxative such as PEG 4000, PEG 3350 (e.g. Laxido®) may reduce plasma sodium levels²¹⁴
• long-term use and misuse of laxatives is associated with electrolyte imbalance, such as hypokalaemia

Faecal impaction treatment

• osmotic laxatives are the first-line treatment, especially if there are hard stools
• an oral stimulant laxative should be prescribed for those with soft stools, or with hard stools after a few days’ treatment with a macrogol. This can be started or added to the macrogol treatment
• If the individual has not fully responded, then
  • in those with soft stools, rectal laxative administration should be considered e.g. bisacodyl suppository
  • harder stools may require glycerol, or glycerol and bisacodyl, with docusate sodium or sodium citrate enema as alternatives²¹⁵
• bulk-forming laxatives, e.g. ispaghula are contra-indicated

Constipation²¹¹

If non-pharmacological options fail, then a stepped treatment approach should be undertaken:

• first line: bulk forming laxatives e.g. ispaghula. Note: individuals prescribed bulk forming laxatives should maintain adequate fluid intake during treatment
• second line or add on: osmotic/stool softening e.g. lactulose, macrogol. Note: advise individual to maintain adequate fluid intake with osmotic laxatives
• third line: add in stimulant e.g. senna, sodium picosulfate

NICE recommend alternative drugs such as prucalopride for constipation which has not responded to above treatment.²¹¹ However this is not currently recommended by Scottish Medicines Consortium and should not be routinely prescribed.

HCPs should be aware that some individuals may purchase over the counter remedies which increase bowel movement frequency and cause side effects such as flatulence. Psyllium has a bulk forming effect and should not be taken by those prescribed opioids or suspected faecal impaction or at bedtime.²¹⁴

If symptoms do not improve with above treatments, then consider

• biochemical factors e.g. hypothyroidism, hypercalcaemia²¹¹
• specialist advice should be sought²¹¹
• referral to continence service or dietician services²¹¹

• faecal impaction regimes should be fully completed
• when symptoms persist after review of lifestyle and medication changes
• when constipation-inducing medication cannot not be stopped
• when constipation is an intrinsic part of another condition e.g. Parkinson’s disease, multiple sclerosis
• Clozapine can cause potentially fatal constipation which needs monitoring and active treatment, therefore do not stop laxatives in this case²¹⁶

Long-term use and abuse of laxatives is associated with fluid loss and electrolyte imbalance, such as hypokalaemia. Individuals should stop treatment if they experience symptoms of fluid and electrolyte disturbances e.g. thirst, lethargy.²¹¹

Consider if the individual is buying over the counter laxatives before prescribing and if any potential abuse.

Patients with impaired cardiovascular function: For the treatment of faecal impaction the dose should be divided so that no more than two sachets are taken in any one hour.

Review those using multiple laxatives for a prolonged period of time as this has the potential to increase the risk of adverse effects, as detailed above.

People prescribed multiple laxatives should be reviewed. Education is key in helping individuals understand why multiple laxatives are not recommended long-term along with the importance of making healthier choices e.g. diet and physical activity.

NICE recommend:

• reducing/stopping stimulant laxatives first then reviewing response
• reducing/stopping other laxatives gradually where appropriate in individuals prescribed multiple laxatives
• laxatives should not be abruptly stopped in individuals prescribed more than one laxative²¹¹

Caution should be taken stopping/reducing antimuscarinic drugs which are deemed to be contributing towards constipation. Such drugs should be reduced gradually to prevent discontinuation/withdrawal symptoms e.g. diarrhoea, sweating, vomiting.²¹⁷

Does the person understand the outcomes of the review, including risk and benefits?

• Help the individual to understand what a “normal” bowel habit is for them. Educate people on the potential risks of long-term laxative use e.g. electrolyte imbalance

Is drug therapy tailored to the individual?

• Individuals prescribed laxatives for overflow diarrhoea may struggle to understand the rationale behind laxative treatment. They may incorrectly stop before disimpaction treatment is complete, due to initial worsening of diarrhoea.
• Check that the individual understands the reason for reducing/stopping constipation inducing drugs.
• Consider those with reduced mobility and access to toilet facilities.²¹¹

Agree and share the plan

• Educate on non-pharmacological methods for managing constipation
• Ensure any “red flag” symptoms are recognised and addressed e.g. unintended weight loss, bleeding, iron deficiency anaemia

• self-management/support tools
• decision aids

NHS Inform – summary of constipation, causes, treatment and prevention

Fibre food fact sheet from the Association of UK Dietitians

5-a-day fruit and vegetable fact sheet from the Association of UK Dietitians