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Bisacodyl - Brand name: Dulcolax

On this page

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

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 also 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 anus).

The tablets and suppositories are available on prescription. Small packs are available to buy from supermarkets (up to 20 tablets).

Before trying bisacodyl, it's better to try other ways to help your constipation by:

Only use bisacodyl if you have tried other types of laxatives first such as:

2. Key facts

  • Bisacodyl is known as a stimulant laxative. It relieves constipation by helping your bowel move so you can poo more easily. It also softens your poo.
  • 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 after you've used them.
  • The most common side effects are feeling sick (nausea), diarrhoea, stomach pain or cramps.
  • Only give bisacodyl to children and young people if a doctor or pharmacist recommends it.
  • Do not take bisacodyl tablets or use bisacodyl suppositories every day for more than 5 days.

3. Who can and cannot take bisacodyl

Bisacodyl can be used by most adults aged 18 years and over.

Young people aged 12 to 17 years can take bisacodyl tablets and use suppositories if a doctor or pharmacist says it's OK.

Children aged 11 years and under can only take and use bisacodyl if a doctor prescribes it.


Only give bisacodyl to someone under the age of 18 if a doctor or pharmacist recommends it.

Bisacodyl is not 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 medicine
  • signs of dehydration – these include peeing less than usual or having dark, strong-smelling pee
  • severe stomach pain and you are feeling 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
  • a problem with the muscles in your bowel not being able to move food and liquid along

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 anus

4. How and when to take or use bisacodyl

Always follow the advice of a pharmacist or doctor, and the instructions that come with your medicine.

Dosage for tablets

Bisacodyl tablets you buy (self-treatment)

The usual dose for adults and young people aged 12 years and over is 5mg to 10mg, taken once a day at bedtime.

If you have not taken bisacodyl before, start with one 5mg tablet and if that does not work you can increase the dose to a maximum of two 5mg tablets (10mg) at bedtime.

Important: Information for ages 12 to 17

Only give bisacodyl tablets that you buy to someone aged 12 to 17 years if a doctor or pharmacist recommends it.

Bisacodyl tablets prescribed by a doctor

The usual starting dose for adults, and children aged 4 years and over, is 5mg, taken once a day at bedtime. A doctor may prescribe higher doses (up to a maximum of 20mg, taken once a day) if necessary.

Dosage for suppositories

The usual dose for:

  • adults – one 10mg suppository, used once a day in the morning
  • children aged 2 to 17 years – one 5mg or 10mg suppository, used once a day in the morning (on doctor's advice only)

How to take tablets

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 take them with milk.

Do not take bisacodyl tablets at the same time as:

  • dairy products like milk, cheese or yoghurt
  • indigestion remedies (antacids)
  • medicines to reduce stomach acid (like proton pump inhibitors such as omeprazole or pantoprazole)

Leave a gap of 1 hour between taking any of these and taking your bisacodyl tablets. This is because they will stop the medicine working properly.

How to use suppositories

Read the instructions in the leaflet inside the package. They will explain how to use the suppository.

Take the wrapping off and push a suppository gently into your anus (bottom).

Suppositories work quickly (usually between 10 and 45 minutes), so use it when you know you will be near a toilet.

What if I forget to take it?

If you forget a dose of bisacodyl, 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 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 do not 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 (anaphylaxis) to bisacodyl.

Immediate action required: Call 999 now if:
  • your lips, mouth, throat or tongue suddenly become swollen
  • you're breathing very fast or struggling to breathe (you may become very wheezy or feel like you're choking or gasping for air)
  • your throat feels tight or you're struggling to swallow
  • your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
  • you suddenly become very confused, drowsy or dizzy
  • someone faints and cannot be woken up
  • a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)

You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling.

These can be signs of 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 using the Yellow Card safety scheme.

Visit Yellow Card for further information.

6. How to cope with side effects of bisacodyl

What to do about:

  • feeling sick – try taking bisacodyl with some food. It may also help if you avoid rich or spicy 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. Do not 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 and pregnancy

Bisacodyl tablets or suppositories are not generally recommended if you are pregnant. Talk to your doctor about whether taking bisacodyl is right for you.

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

If diet and lifestyle changes do not work, your doctor or midwife may recommend other laxatives, such as lactulose or Fybogel. These are more suitable to take during pregnancy and while breastfeeding.

Bisacodyl and breastfeeding

If your doctor or midwife recommends bisacodyl, rather than lactulose or Fybogel, it's OK to use it while you're breastfeeding. It does not seem to pass into breast milk and is very unlikely to affect your baby.

As with any medicine, if you notice that your baby is not feeding as well as usual, or if you have any other concerns about your baby, talk to your health visitor, midwife or doctor as soon as possible.

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

  • trying to get pregnant
  • pregnant
  • breastfeeding

For more information about how bisacodyl can affect you and your baby during pregnancy, read this leaflet on the Best Use of Medicines in Pregnancy (BUMPS) website.

8. Cautions with other medicines

Some medicines, and some foods, affect the way bisacodyl works.

They include:

  • medicines that make you pee more (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. If you are taking digoxin, this imbalance makes it more likely you will have the serious side effects of digoxin. Talk to a doctor or pharmacist before taking bisacodyl if you are taking any of these medicines.
  • indigestion remedies (antacids) – these stop bisacodyl tablets 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.

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. They are not tested in the same way as other medicines.

Important: Medicine safety

Tell your doctor or pharmacist if you're taking any other medicines, including herbal medicines, vitamins or supplements.

9. Common questions about bisacodyl

How does bisacodyl work?

Bisacodyl is known as a stimulant laxative. It 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 will I take bisacodyl for?

Do not take bisacodyl every day for more than 5 days.

If you take bisacodyl for longer, your body can start to rely on it, rather than your bowels doing the work on their own.

If you are still constipated after 5 days, talk to your doctor.

Is it safe to take bisacodyl for a long time?

It's best to only use bisacodyl occasionally and for a few days at a time.

Using laxatives like bisacodyl for longer than this can lead to diarrhoea.

It can also cause an electrolyte (or salt) imbalance, where levels sodium, potassium and magnesium in your body get too high or too low. A severe electrolyte imbalance can cause serious health problems such as muscle spasm and twitching, and even convulsions.

Using bisacodyl for many weeks, even months, could also stop your bowel working properly on its own.

If you need to use laxatives every day for longer than 5 days, 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 tells you to, as this increases the risk of side effects.

Are other laxatives any better?

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

Bulk-forming laxatives, such as Fybogel and methylcellulose, increase the "bulk" or weight of poo, which in turn stimulates bowel movement. They take 2 or 3 days to work.

Osmotic laxatives, such as lactulose, draw water from the rest of the body into your bowel to soften your poo and make it easier for you to go to the toilet. They take at least 2 days to work.

Stimulant laxatives, like senna, stimulate the muscles that line your gut, helping them to move poo along your gut to your anus (bottom). Senna takes about 8 hours to work.

Will it affect my fertility?

There's no evidence to suggest that taking bisacodyl will reduce fertility in either men or women.

Will it affect my contraception?

Bisacodyl does not affect any type of contraception including the combined pill and emergency contraception.

But if you have severe diarrhoea for more than 24 hours, your contraceptive pills may not protect you from pregnancy. Look on the pill packet to find out what to do.

Find out more:

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 will not affect your bisacodyl tablets.

If you're constipated it's a good idea to stop eating pastries, cakes, puddings and cheese for a while, as foods high in fat 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 lactulose because it is gentler than bisacodyl. You can get it on prescription or buy it from pharmacies.

Can lifestyle changes help with constipation?

You can often improve constipation without having to use laxatives. Before trying bisacodyl, or to stop your 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 – this helps 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

Page last reviewed: 14 June 2021
Next review due: 14 June 2024