Patient information · Gastroenterology
Constipation
including which laxative, and why it matters
Constipation is extremely common and usually straightforward to treat. The two things worth getting right are recognising the small number of presentations that need investigating, and choosing the right type of laxative — because people frequently take one that cannot help with their particular problem.
Arrange assessment promptly if you have
- a persistent change in bowel habit lasting three weeks or more, especially over 50
- bleeding from the back passage, or black tarry stools
- unexplained weight loss, or a lump in the abdomen
- severe abdominal pain with vomiting and not passing wind — possible obstruction
- unexplained iron deficiency anaemia
- constipation with numbness in the saddle area or bladder problems — this is an emergency
New constipation in someone over 50, or with bleeding or weight loss, needs investigating under NICE cancer referral guidance rather than treating with laxatives alone. In an emergency call 999, or go to the Royal London Hospital Emergency Department, Whitechapel Road, London E1 1FR.
Common causes
- low fibre, low fluid intake, and inactivity
- medicines — opioid painkillers including codeine, iron tablets, some antidepressants, antacids containing aluminium, and certain blood pressure tablets
- ignoring the urge, or lack of a private toilet at work
- an underactive thyroid, diabetes, low potassium or high calcium
- pregnancy, and the postnatal period
- irritable bowel syndrome, and pelvic floor dysfunction
Two different problems, two different treatments
Slow transit — hard, infrequent stools — responds to bulking and osmotic laxatives. Difficulty evacuating — soft stool that will not come out, straining, a sense of incomplete emptying, needing to press on the vagina or perineum — is a pelvic floor problem, and more laxative makes it worse. It responds to bowel retraining and pelvic floor physiotherapy. If you are straining on soft stool, adding fibre is the wrong answer.
Which laxative
- Bulk-forming (ispaghula, methylcellulose) — first choice for most people. Must be taken with plenty of fluid, and are unsuitable for opioid-induced constipation or where evacuation is the problem. Takes two to three days.
- Osmotic (macrogol, lactulose) — draws water into the stool. Macrogol is generally preferred; lactulose commonly causes bloating and wind. Takes one to three days.
- Stimulant (senna, bisacodyl) — makes the bowel contract. Works within 8 to 12 hours. Useful short-term and for opioid-induced constipation. Long-term daily use is no longer thought to damage the bowel, but it is still better to establish a regimen with an osmotic base.
- Suppositories and enemas for hard stool in the rectum, or where oral treatment has not worked.
- For opioid-related constipation, start a stimulant plus osmotic laxative at the same time as the opioid rather than waiting.
- Newer prescription options exist for chronic constipation not responding to standard laxatives.
Practical measures
Helps
- 30g fibre daily, increased gradually over weeks to avoid bloating
- Plenty of fluid — fibre without fluid makes things worse
- Going after breakfast, when the bowel is most active
- A footstool to raise the knees above the hips, which straightens the passage
- Regular walking; kiwi fruit, prunes and linseed all have evidence
Hinders
- Ignoring the urge and 'holding on'
- Straining hard, which causes piles and worsens pelvic floor problems
- Sitting on the toilet for long periods with a phone
- Adding more fibre when the problem is evacuation
- Rushing, or having no private time in the morning
Positioning
Sitting with the knees higher than the hips — using a small footstool — relaxes the muscle that maintains continence and straightens the passage. Lean forward with elbows on knees, keep the back straight, and breathe out rather than holding your breath and bearing down. This alone helps a great many people and costs nothing.
Why come to us. Persistent constipation deserves a cause, not just a laxative. We take a proper history, examine you, check thyroid function, calcium, glucose and full blood count in-house with results the same visit, review every medicine you take, and identify whether the problem is transit or evacuation — because that determines the treatment. We refer for pelvic floor physiotherapy, and arrange colonoscopy through our CQC-registered partners where investigation is warranted.
The cause found, and the right laxative chosen
Bloods in-house, results the same visit. Seven days a week.
Tower Bridge Hospital London
97–99 Whitechapel Road, London E1 1DT
WhatsApp 07903 284 189
info@mhwclinic.co.uk
Open Mon–Sat, 9am–7pm (closed Sundays until September)
In an emergency
Call 999, or go to the Royal London Hospital Emergency Department, Whitechapel Road, London E1 1FR.
When we are closed and it is not an emergency
Call NHS 111 or visit 111.nhs.uk.