Bisacodyl: laxative to treat constipation - NHS

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  1. About bisacodyl
  2. Key facts
  3. Who can and can't take bisacodyl
  4. How and when to take it
  5. Side effects
  6. How to cope with side effects
  7. Pregnancy and breastfeeding
  8. Cautions with other medicines
  9. Common questions

1. About bisacodyl

Bisacodyl is a laxative. This type of medicine can help you empty your bowels if you have constipation (difficulty pooing).

Bisacodyl is used in hospitals to help you empty your bowels before surgery or some examinations or treatments. Your hospital will explain how to use it.

Bisacodyl comes as a tablet and a suppository (a medicine that you push gently into your back passage).

The tablets and suppositories are available on prescription and to buy from pharmacies.

2. Key facts

  • Bisacodyl tablets take 6 to 12 hours to work. The suppositories take 10 to 45 minutes to work, so it's best to stay close to a toilet.
  • The most common side effects are feeling sick (nausea), diarrhoea, stomach pain or cramps.
  • Only give bisacodyl to children if their doctor recommends it.
  • Do not take bisacodyl tablets or use bisacodyl suppositories every day for more than 5 days.
  • Bisacodyl is also called by the brand name Dulcolax.

3. Who can and can't take bisacodyl

Bisacodyl can be used by adults.It can also be used by children, if their doctor recommends it. Doctors normally only recommend it for children aged 4 years and older.

Occasionally, they recommend it for children aged 2 years and older.


Only give bisacodyl to children if their doctor recommends it.

Bisacodyl isn't suitable for some people. To make sure it's safe for you, tell your doctor or pharmacist if you have:

  • ever had an allergic reaction to bisacodyl or any other medicines in the past
  • signs of dehydration
  • severe stomach pain and you are feeling sick or being sick (nausea or vomiting)
  • a serious problem in your stomach (abdomen), such as appendicitis, a blockage in your bowel (intestinal obstruction), ulcerative colitis or Crohn's disease, or a problem with the muscles in your bowel not being able to move food and liquid along

For tablets, also tell your doctor or pharmacist if you:

  • can't digest some sugars - the tablets contain a small amount of lactose and sucrose

For suppositories, also tell your doctor or pharmacist if you have:

  • ever had an allergic reaction to suppositories
  • tears or open sores (anal fissures) or cracked skin around your back passage (anus)

4. How and when to take it

How to take it


  • Take the medicine once a day just before bedtime.
  • You can take it with or without food. Swallow the tablet whole with water.
  • Do not have milk, indigestion remedies (antacids) or medicines to reduce stomach acid (for example, proton pump inhibitors) at the same time as bisacodyl. This is because they will stop the medicine working properly. Leave a gap of 1 hour between taking any of these and taking your bisacodyl tablets.


  • Take the wrapping off and push a suppository gently into your back passage (anus).
  • Suppositories work quickly (usually between 10 and 45 minutes), so use it when you know you will be near a toilet.
  • Read the instructions in the leaflet inside the package. They will explain how to use the suppository.

How much to take


The usual dose in:

  • adults and children aged 10 years and over is 1 or 2 tablets once a day before bedtime
  • children aged 4 to 10 years old is 1 tablet a day before bedtime, if their doctor recommends it

If you are an adult or child aged 10 and over and you have not taken bisacodyl before, start with 1 tablet. If that doesn't work well enough for you, you can take 2 tablets.


The usual dose for:

  • adults and children aged 10 years and over is 1 suppository (10mg) a day
  • children under 10 years old is 1 suppository (5mg) a day, if their doctor recommends it

What if I forget to take it?

If you forget a dose of bisacodyl, don't worry. Just take the next dose at the usual time.

Never take 2 doses at the same time. Never take an extra dose to make up for a forgotten one.

What if I take too much?

Taking an extra dose of bisacodyl by accident is unlikely to harm you. You may get diarrhoea and stomach pain, but this should get better within a day or two.

If you're worried, talk to your doctor or pharmacist for advice.

5. Side effects

Like all medicines, bisacodyl may cause side effects in some people, but many people have no side effects or only minor ones.

Common side effects

Common side effects, which happen in more than 1 in 100 people, are:

  • feeling sick (nausea)
  • diarrhoea
  • stomach pain or cramps

These side effects are mild and usually go away after a couple of days. Talk to your doctor or pharmacist if the side effects bother you or don't go away.

Serious side effects

Call your doctor straight away if these rare side effects happen to you:

  • feeling dizzy
  • blood in your poo
  • being sick (vomiting)

Serious allergic reaction

In rare cases, it's possible to have a serious allergic reaction to bisacodyl.

Immediate action required: Call 999 or go to A&E if:

  • you get a skin rash that may include itchy, red, swollen, blistered or peeling skin
  • you're wheezing
  • you get tightness in the chest or throat
  • you have trouble breathing or talking
  • your mouth, face, lips, tongue or throat start swelling

You could be having a serious allergic reaction and may need immediate treatment in hospital.

These are not all the side effects of bisacodyl. For a full list, see the leaflet inside your medicines packet.


You can report any suspected side effect to the .

6. How to cope with side effects

What to do about:

  • feeling sick - try taking bisacodyl with some food.
  • diarrhoea - stop taking bisacodyl and drink plenty of water or other fluids. Speak to a pharmacist if you have signs of dehydration, such as peeing less than usual or having dark, strong-smelling pee. Don't take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.
  • stomach pain or cramps - reduce your dose of bisacodyl or stop taking it until these side effects go away.

7. Pregnancy and breastfeeding

Bisacodyl tablets or suppositories are not generally recommended if you are pregnant, especially in the first 3 months and while you are breastfeeding. Talk to your doctor about the benefits and risks of taking bisacodyl.

If you are pregnant or breastfeeding, it's always better to try to treat constipation without taking a medicine. Your doctor or midwife will first advise you to eat more fibre and drink plenty of fluids. It may also help to do gentle exercise.

If diet and lifestyle changes do not work, your doctor or midwife may recommend another laxative, such as or . These are safer laxatives to take during pregnancy and while breastfeeding.

Non-urgent advice: Tell your doctor if you're:

  • trying to get pregnant
  • pregnant
  • breastfeeding

8. Cautions with other medicines

Some medicines - and some foods - interfere with the way bisacodyl works.

They include:

  • water tablets (diuretics), steroids (like prednisolone) or digoxin (a heart medicine) - these can upset the balance of salts and minerals in your body if you have too much bisacodyl by accident. If you are taking digoxin, this imbalance makes it more likely you will have the serious side effects of digoxin. It's important not to take too much bisacodyl if you are taking any of these medicines.
  • indigestion remedies (antacids) and dairy products, like milk, cheese and yoghurt - these interact with bisacodyl tablets and stop them working properly. They can also make the bisacodyl irritate your stomach and give you indigestion. Do not take bisacodyl at the same time - leave a gap of 1 hour before or after taking bisacodyl if you are having indigestion remedies or dairy products. The small amount of milk in coffee and tea is unlikely to affect it, but it's best to take bisacodyl tablets with a glass of water.

Mixing bisacodyl with herbal remedies or supplements

There is not enough research to know if complementary medicines and herbal remedies are safe to take with bisacodyl.


For safety, tell your doctor or pharmacist if you are taking any other medicines, including herbal remedies, vitamins or supplements.

9. Common questions

How does bisacodyl work?

Bisacodyl relieves constipation by helping your bowel move so you can poo more easily. It also softens your poo.

When will I feel better?

Bisacodyl tablets usually work within 6 to 12 hours after taking them.

The suppositories can take 10 to 45 minutes, so it's best to stay close to a toilet.

How long should I take bisacodyl for?

Do not take bisacodyl every day for more than 5 days. If you are still constipated after that, talk to your doctor.

Is it safe to take bisacodyl for a long time?

Ideally, you should only use bisacodyl occasionally and for a few days at a time.

Using laxatives like bisacodyl for longer can lead to a fluid and salt imbalance in your body and you may become dehydrated.

If you need to use laxatives every day for a longer time, talk to your doctor.

Can I take different laxatives together?

For most people, 1 laxative will be enough to make your constipation better.

Occasionally, you may need to take 2 different types of laxatives at the same time to get your bowels moving again. Only take 2 laxatives together if your doctor or pharmacist tell you to as this increases the risk of side effects.

Are other laxatives any better?

There are other types of laxative. They work in a different way from bisacodyl, but are equally good at treating constipation.

  • Bulk-forming laxatives, for example and methylcellulose. These increase the "bulk" or weight of poo, which in turn stimulates bowel movement. They take 2 or 3 days to work.
  • Osmotic laxatives, for example . These draw water from the rest of the body into your bowel to soften your poo and make it easier to pass. They take at least 2 days to work.
  • Stimulant laxatives, for example . These stimulate the muscles that line your gut, helping them to move poo along your gut to your back passage. Senna takes about 8 hours to work.
Is there any food and drink I need to avoid?

Do not take bisacodyl at the same time as dairy products like milk, cheese or yoghurt. Leave a gap of 1 hour between taking any of these and taking your bisacodyl tablets. The small amount of milk in coffee and tea should not affect the bisacodyl tablet.

It's a good idea to stop eating pastries, cakes, puddings and cheese for a while as these can make constipation worse.

Can I drink alcohol with it?

Yes, you can drink alcohol with bisacodyl.

Can I use bisacodyl after surgery?

It's quite common to have constipation after surgery. Using a laxative may help.

If you have constipation after an operation, it's better to use because it is gentler than bisacodyl. You can get it on prescription or buy it from pharmacies.

Can lifestyle changes help constipation?

It's often possible to improve constipation without having to use laxatives. Before trying bisacodyl - or to stop constipation coming back - it may help to:

  • eat more fibre - aim for about 30g of fibre a day. High-fibre foods include fruit, vegetables and cereals. If you're not used to a high-fibre diet, increase the amount of fibre you eat gradually.
  • add bulking agents, such as wheat bran, to your diet. These will help make your poo softer and easier to pass (although bran and fibre can sometimes make bloating worse).
  • drink plenty of water - to keep poo soft.
  • exercise regularly - keeping your body active will help to keep your gut moving.
  • go to the toilet when you need to, rather than holding it in.

Useful resources

Page last reviewed: 19 April 2018
Next review due: 19 April 2021