A stimulant laxative

Bisacodyl

A stimulant laxative for short-term relief of constipation; it can cause tummy cramps and is not meant for long-term use.

What is Bisacodyl?

Bisacodyl is a stimulant laxative used for the short-term relief of constipation, and to empty the bowel before some medical tests or surgery. It works by stimulating the bowel muscles to move, helping to produce a bowel movement. It can cause tummy cramps, and it is not intended for regular long-term use.

Education and reference only. This is a plain-language guide to Bisacodyl — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.

Written by Meds Global Health Clinical Team · Clinically reviewed by Dr Muhammad Suffyan, MB BS, Founder & Clinical Director · Last reviewed · How we review
Class: Laxatives → Brands: Dulcolax
Bisacodyl (Laxatives) — Meds Global Health reference card with 2D molecular structure
Bisacodyl — Laxatives. The image shows the active ingredient's 2D molecular structure.

What it is

Bisacodyl is a stimulant laxative used in the UK for the short-term relief of constipation and to clear the bowel before certain investigations or operations. It is available as tablets (which have a special coating) and as suppositories that are inserted into the back passage and tend to work more quickly. It relieves constipation but does not address its underlying causes, such as a low-fibre diet, not drinking enough fluid or being inactive, so it is best used alongside these measures and only for a short time.

How it works

Bisacodyl stimulates the nerves in the wall of the large bowel, increasing the muscular squeezing movements (peristalsis) that push stool along. It also encourages the bowel to hold more water in the stool, making it softer and easier to pass. Together these actions trigger a bowel movement. Tablets are taken by mouth and usually work overnight, while suppositories act directly in the lower bowel and tend to work within a shorter time.

Company & origin

Originated / developed by: Originally developed by Boehringer Ingelheim..

Bisacodyl is a stimulant laxative introduced in the 1950s and widely used for short-term relief of constipation and to clear the bowel before some procedures.

Practical use

How to take Bisacodyl

General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.

  • Use it for short-term relief only, not as a regular long-term remedy.
  • Swallow the tablets whole with water — do not crush, chew or break them, as they have a special coating.
  • Do not take the tablets at the same time as milk or antacids; leave a gap, as these can damage the coating and cause stomach irritation.
  • Tablets are often taken at night so they work by the next morning, while suppositories tend to work more quickly.
  • Drink plenty of fluids, and combine it with more fibre and activity to help the bowel work naturally.
  • See a doctor if constipation persists, keeps returning, or comes with severe pain, bleeding or unexplained weight loss.

Weighing it up

Advantages & disadvantages of Bisacodyl

Advantages

  • It provides reliable short-term relief of constipation.
  • It comes as tablets and as faster-acting suppositories, so the form can suit the need.
  • It is also useful for clearing the bowel before some medical procedures.

Disadvantages

  • It commonly causes tummy cramps because it stimulates the bowel muscles.
  • It is not suitable for long-term use, as the bowel can become reliant on it.
  • It does not address the underlying causes of constipation, such as low fibre or fluid intake.

Practical use

Good to know

Bisacodyl is meant for short-term use; using stimulant laxatives regularly for a long time can lead to the bowel becoming reliant on them and is best avoided. Tummy cramps are a common effect because it works by stimulating the bowel muscles. The tablets have a special (enteric) coating designed to dissolve further down the gut, so they must be swallowed whole and not crushed or chewed; avoid taking them with milk or antacids around the same time, as these can break down the coating too early and cause stomach irritation. Drink plenty of fluids while using it. If constipation keeps coming back, or there is a sudden change in bowel habit, blood in the stool, unexplained weight loss or severe tummy pain, see a doctor rather than simply continuing laxatives.

Who should not take it / use with caution

  • People with a suspected bowel blockage, severe tummy pain, or an acute serious bowel condition.
  • People who are seriously dehydrated.
  • Anyone who has had an allergic reaction to bisacodyl.

Monitoring

  • Checking that constipation has resolved and the laxative is no longer needed.
  • Watching for persistent or recurring constipation that needs proper assessment.
  • With overuse, watching for dehydration and disturbances in body salts.

Side effects

  • Tummy cramps and a feeling of urgency.
  • Diarrhoea, especially if too much is used.
  • Nausea.
  • With overuse, disturbances in the body's salts and a lazy bowel.

Key interactions

  • Do not take the tablets with milk or antacids around the same time, as they can damage the protective coating.
  • Overuse can lower body potassium, which may add to the effects of medicines such as digoxin or some heart medicines.
  • Other medicines affecting body salts may need to be considered with prolonged use.

Available as: Tablets (with a special coating) and suppositories.

Answers

Bisacodyl: frequently asked questions

How quickly does bisacodyl work?

Tablets are usually taken at night and tend to produce a bowel movement by the next morning, while suppositories act in the lower bowel and generally work more quickly. The exact timing varies from person to person.

Why must I swallow the tablets whole?

The tablets have a special (enteric) coating that is designed to dissolve further down the gut. Crushing or chewing them, or taking them with milk or antacids, can break the coating too early, which may irritate the stomach and stop the tablet working as intended.

Can I use bisacodyl every day?

No. It is intended for short-term relief. Using stimulant laxatives regularly over a long period can make the bowel rely on them. If you need a laxative often, see a doctor or pharmacist to look at the cause and consider a gentler approach.

Why do I get tummy cramps with it?

Bisacodyl works by stimulating the muscles in the bowel wall to squeeze and move stool along, and this activity can cause cramping. The cramps usually settle once you have had a bowel movement.

When should I see a doctor about constipation?

See a doctor if constipation persists despite treatment, keeps returning, or comes with a sudden change in bowel habit, severe tummy pain, blood in the stool or unexplained weight loss. These need proper assessment rather than continued laxative use.

The wider class

About Laxatives

Bisacodyl belongs to the laxatives class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.

LaxativesDifferent types for different problems — chosen by cause and stool consistency. DocusateA gentle stool-softener laxative that makes stools easier to pass; it works mildly and is …LactuloseAn osmotic laxative that softens stools by drawing water into the bowel; it takes a day or…Ispaghula huskA bulk-forming laxative (fibre) that must be taken with plenty of water; never take it jus…Sodium picosulfateA stimulant laxative, usually taken at night, for short-term constipation or to clear the …Magnesium hydroxideA gentle osmotic laxative that also works as an antacid, best known as milk of magnesia.…Glycerol suppositoriesA simple suppository inserted into the back passage to relieve constipation quickly.…SennaA stimulant laxative that encourages the bowel to move, used for short-term relief of cons…MacrogolAn osmotic laxative that draws water into the bowel to soften stool and relieve constipati…Arachis oil enemaA peanut (arachis) oil retention enema used rectally to soften hard, impacted stools so th…Co-danthramerA combination stimulant laxative used mainly for constipation in people receiving palliati…Co-danthrusateA combination stimulant laxative used mainly for constipation in people receiving palliati…ElobixibatA laxative for chronic constipation that works by increasing bile acids in the bowel to dr…Glycerol suppositoryA rectal suppository that relieves constipation by softening the stool and gently stimulat…Magnesium citrateAn osmotic laxative used for constipation and to clear the bowel before procedures, workin…MethylcelluloseA bulk-forming laxative that adds bulk to the stool to ease constipation, taken with plent…NaldemedineA once-daily tablet that treats constipation caused by opioid painkillers without reducing…NaloxegolA once-daily tablet for opioid-induced constipation that blocks opioids in the gut without…Phosphate enemaA phosphate rectal enema used for rapid relief of constipation and to clear the bowel befo…PlecanatideA daily tablet used for chronic constipation and constipation-type IBS in adults.…PrucaloprideA daily tablet used for chronic constipation when ordinary laxatives have not worked well …Sodium citrate enemaA small osmotic enema inserted into the back passage to relieve occasional constipation, w…SterculiaA bulk-forming laxative made from plant fibre that treats constipation and helps regulate …

Browse by body system

Digestive systemConditions and medicines for the gut — acid reflux, ulcers, IBS, constipation, nausea and …

Authoritative sources

  • BNF
  • NICE CKS

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