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11/13/24, 7\:44 PM Guide | Prescribing laxatives

Prescribing laxatives

Table of contents

Introduction

Laxatives are used to treat constipation in patients. Prescribing laxatives is a common task for all clinicians and frequently
appears in medical school exams and the Prescribing Safety Assessment (PSA).
This article will cover the di
guidelines and refer to the BNF before prescribing.

Constipation

Constipation is a symptom-based disorder where patients describe problematic defecation because of infrequent stools,
hard stools, di
In practice, it is often de1
many patients de
, with no reference to frequency.
It is worth noting that
Constipation is more common in the elderly population, and the incidence of constipation is 2-3 times higher in women than in
men. The UK primary care cohort study found the prevalence of GP-diagnosed constipation was 12.8/1000 people. However,
prevalence is thought to be much higher because people appropriately self-treat using over-the-counter remedies and
medications rather than consulting healthcare professionals.
1
Constipation rarely causes complications or long-term health problems, and treatment is usually e
given promptly. 2
Chronic constipation is more likely to cause complications and medical emergencies. Complications include
faecal loading/impaction, faecal incontinence, haemorrhoids, anal
obstruction and bowel perforation.

Causes of constipation

If a patient presents with constipation, consider the causes of the constipation.
Identifying any associated symptoms (e.g., abdominal pain, weight loss, fatigue) that may indicate a sinister underlying
condition such as gastrointestinal malignancy is important. These red-
blood tests and qFIT testing.
The examination of a constipated patient will depend on the clinical context but may include\:
Abdominal examination\: this may assist in identifying the cause of constipation (e.g. deeper abdominal masses); it will also
assess for abdominal tenderness and signs of peritonitis
Rectal examination\: this may identify the causes of constipation (e.g. if there are any
assess for hard stool in the rectum
Basic observations (vital signs)\: may be useful if assessing an acutely unwell patient with constipation to check for
haemodynamic stability or if there are any associated fevers
Assessing hydration status\: assessing hydration could be helpful when considering if dehydration may be the
cause/contribution of constipation
Underlying medical condition
Constipation can be caused by an underlying medical condition (i.e., secondary constipation). Examples include\:
Endocrine disorders\: hypothyroidism (causing slowed metabolism and reduced peristalsis)
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Neurological disorders\: multiple sclerosis (causing reduced/absent autonomic, sensory and motor responses)
Myopathic diseases\: myotonic dystrophy (causing muscle weakness/spasm)
Structural abnormalities\: haemorrhoids, anal
Iatrogenic causes
Constipation can be caused by a variety of medications (iatrogenic constipation). Examples include\:
Opioids
Iron supplements
Tricyclic antidepressants
Antipsychotics
Pregnancy
Constipation in pregnancy is common and occurs due to the increase in progesterone, which relaxes intestinal smooth
muscle.
Psychological causes
Psychological causes of constipation include\:
Anxiety and depression (causing altered/reduced intake, reduced movement, altered muscle re
Somatisation disorders (causing altered neuromuscular response in the bowel)
Eating disorders (from poor intake and/or laxative abuse creating dependence)
Irritable bowel syndrome
Irritable bowel syndrome can cause constipation and recurrent abdominal pain. The Rome IV criteria are used to
diagnose IBS. 3
The Bristol stool chart can be used to assess stool consistency objectively.

Types of laxative

Laxatives have di
consider the reason for constipation and choose the appropriate laxative.
In the community, some laxatives can be bought over the counter from pharmacies, and others require a medical prescription.
Bulk-forming laxatives
Examples\: ispaghula husk (Fybogel), methylcellulose (Celevac)
Bulk-forming laxatives 'bulk out' the stool with soluble
action is up to 72 hours, and common adverse e
Patients should be advised to increase
Osmotic laxatives
Examples\: lactulose, macrogols (Movicol, Laxido)
Osmotic laxatives draw water via osmosis into the stool, making it softer and easier to pass. Adverse e
cramps, diarrhoea, nausea and vomiting.
Hepatic encephalopathy
Lactulose is used to treat hepatic encephalopathy as it reduces the intestinal production and absorption of ammonia.
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Stimulant laxatives
Examples\: senna (Senokot), bisacodyl (Dulcolax), sodium picosulfate
Stimulant laxatives stimulate the nerves of the digestive tract to cause peristalsis.
Stool softening laxatives
Examples\: docusate
Stool softening laxatives decrease the surface tension of faecal mass and increase intestinal
Other
Glycerol suppositories are both a lubricant and a rectal stimulant.
Prokinetic laxatives are selective serotonin receptor agonists which stimulate intestinal motility. These should only be used
under specialist advice.

Prescribing laxatives

Do not prescribe laxatives for patients with suspected bowel obstruction or perforation.
Before advising or prescribing the medical treatment of laxatives, consider lifestyle advice\:
Increasing calorie intake
Body position when passing stool
Increased dietary
Increased movement and exercise
Ensure adequate hydration
Short term constipation
For patients with short-term onset constipation\:
Step 1\: Start bulk-forming laxative
Step 2\: Add or switch to an osmotic laxative
Step 3\: Add stimulant laxative
Opioid-induced constipation
For patients with opioid-induced constipation\:
Step 1\: Start osmotic laxative and stimulant laxative
Step 2\: Add softener laxative
Step 3\: Naloxegol (mechanism\: opioid receptor antagonist)
Faecal impaction4
For patients with faecal impaction (i.e. retention of faeces to the extent that spontaneous evacuation is unlikely), consider oral
macrogol/oral stimulant laxative depending on stool consistency.
4
If there is an inadequate response to oral laxatives, consider rectal administration of bisacodyl/glycerol.
Chronic constipation
For patients with chronic constipation (constipation symptoms for at least three months)\:
5
Step 1\: Start bulk-forming laxative
Step 2\: Add or change to osmotic laxative
Step 3\: Add stimulant laxative
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If at least two laxatives from di
In chronic constipation, always gradually withdraw treatment. In addition, electrolytes should be monitored as there is an
increased risk of derangement (e.g. hypokalemia).
Pregnant/breastfeeding women
In pregnant/breastfeeding women- dietary and lifestyle are important to try
Bulk-forming laxatives are considered the
Common laxatives doses
Examples of common laxative doses include\:
Ispaghula husk\: 1 sachet BD; given in water after food in the morning and evening
Lactulose\: 15ml BD, adjusted according to response
Movicol liquid\: 25 mL 1–3 times a day, usually for up to 2 weeks; maintenance 25 mL 1–2 times daily
Senna\: 7.5mg-15mg OD, usually taken at night; the initial low dose can be gradually increased up to 30mg OD under
medical supervision
Docusate sodium\: 100mg TDS; dose can be increased up to 500mg in divided doses
Always check the BNF before prescribing. Prucalopride, lubiprostone and naloxegol are only prescribed under limited
NICE criteria. Linaclotide is used for IBS under specialist guidance.

Reviewer

Dr Seb Pillon
GP and Primary Care Medical Educator

References

1. NICE CKS. C o n s t i p a t i o n - b a c k g r o u n d i n f o r m a t i o n . Published in 2023. Available from\: [LINK]
2. NHS Inform. C o n s t i p a t i o n . Published in 2023. Available from\: [LINK]
3. 4. MDCalc. R o m e I V D i a g n o s t i c C r i t e r i a f o r I r r i t a b l e B o w e l S y n d r o m e ( I B S ) . Available from\: [LINK]
BNF. C o n s t i p a t i o n | T r e a t m e n t s u m m a r i e s . Available from\: [LINK]
5. NICE CKS. C o n s t i p a t i o n - d e LINK]
Source\: geekymedics.com
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