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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 bisacodyl
  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 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:

  • having more fibre in your diet and drinking more water
  • exercising

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

  • ’bulk-forming’ laxatives like Fybogel (ispaghula husk) and methylcellulose
  • ‘osmotic’ laxatives like lactulose and polyethylene glycol

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.

3. Who can and cannot take bisacodyl

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

Children and young people aged 12 to 17 years can take bisacodyl if a doctor or pharmacist says it’s OK.

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


Only give bisacodyl to children (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 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:

  • cannot 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 fissure) or cracked skin around your anus

4. How and when to take bisacodyl

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.


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.

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



If you buy bisacodyl tablets (self-treatment)

The usual dose for adults, and children 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.


Only give bisacodyl to children aged 12 to 17 years if it has been recommended by a doctor or pharmacist.

If bisacodyl tablets are prescribed by a doctor

The usual starting dose for adults, and children aged 4 years and above, 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.


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)

What if I forget to take it?

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

Immediate action required: Call 999 or go to A&E now 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 using the Yellow Card safety scheme.

Visit Yellow Card for further information.

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. 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 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 lactulose or Fybogel. 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, affect 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. 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) and dairy products, like milk, cheese and yoghurt – these affect 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.

Important: Medicine safety

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

9. Common questions

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?

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

Using laxatives like bisacodyl for longer can lead to diarrhoea and should be stopped.

It can also cause an electrolyte imbalance, where levels of substances like 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 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, such as Fybogel 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 lactulose. 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 senna. 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.
Will it affect my fertility?

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

However, speak to a pharmacist or your doctor before taking it if you're trying to get pregnant.

Will it affect my contraception?

Bisacodyl does not affect any type of contraception including the combined pill and emergency contraception unless you have severe diarrhoea for more than 24 hours.

If you have severe diarrhoea your contraceptive pills may not protect you from pregnancy. Look on the pill packet to find out what to do.

Read more about what to do if you're on the pill and you're vomiting or have diarrhoea.

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 lactulose 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

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