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  1. About macrogol
  2. Key facts
  3. Who can and can't take macrogol
  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 macrogol

Macrogol (or macrogols) is a laxative taken to treat constipation (difficulty pooing). It's also taken to help clear a build-up of hard poo in your bowel, which can happen if you've been constipated for a long time (faecal impaction).

It can also be given before a colonoscopy (a test to check inside your bowels) to empty your bowels before the test. Find out about getting ready for a colonoscopy.

Macrogol comes as sachets of powder that you mix with water to make a drink, a ready-mixed solution to drink, or a liquid that you need to dilute before drinking.

It's available on prescription and to buy from pharmacies.

Macrogol is also called by the brand names Movicol, Laxido, CosmoCol, Molaxole or Molative.

Paediatric powder sachets will be prescribed for children under 12 years of age, these brands include CosmoCol Paediatric and Movicol Paediatric.

2. Key facts

  • Macrogol relieves constipation by making your poo slightly bigger and softer. This helps poo travel through your bowels more easily.
  • Macrogol can take 1 to 2 days to work.
  • The most common side effects are stomach pain, diarrhoea, wind and a sore bottom (anus). These are usually mild and shortlived.
  • Most macrogol sachets contain sodium chloride, potassium chloride and sodium bicarbonate (known as electrolytes).

3. Who can and can't take macrogol

Macrogol can be taken by most adults including pregnant and breastfeeding women. You can buy laxatives with macrogol in for children over 12 years of age. However, babies and children under 12 years old can only take macrogol with a prescription from a doctor.

Macrogol is not suitable for some people. To make sure it's safe for you, tell a doctor or pharmacist if you:

  • have ever had an allergic reaction to macrogol or any other medicine in the past
  • have had a hole or breakage (perforation) in the wall of your intestine
  • have ever had a blockage in your intestines or paralysis of the intestine (for example because of intestinal surgery or severe infection)
  • have ulcerative colitis, Crohn's disease or a rare condition called toxic megacolon
  • are being treated for heart failure or an irregular heartbeat – if you are, never take more than 2 full-strength sachets or 4 half-strength sachets in any 1-hour period. Speak to a doctor about how much you can safely take.
  • have been told you need to follow a low-salt (or low-sodium) diet (especially if you need more than 3 or more sachets a day for a long period of time)

Most types of macrogol contain a lot of sodium (sodium is also found in table and cooking salt). Each dose can contain around 10% of your recommended daily amount of sodium.


Do not give macrogol to a child under 12 years old unless a doctor has prescribed it.

4. How and when to take it

You can take macrogol with or without food.


The amount you take depends on how bad your constipation is. Ask a pharmacist for advice if you're not sure.

The usual dose for constipation for adults and children over 12 years old:

  • full-strength powder sachets (contains around 13g of macrogol) – 1 sachet, taken 1 to 3 times a day
  • half-strength powder sachets (contains around 6g of macrogol) – 1 sachet, taken 2 to 6 times a day in divided doses
  • ready-to-drink solution – 1 sachet, taken 1 to 3 times a day
  • liquid – 25ml diluted in 100ml of water 1 to 3 times a day

Paediatric powder sachets will be prescribed to children under 12 years old.

The usual dose of paediatric sachets for constipation for children aged:

  • 6 to 11 years – 1 sachet, taken twice a day (up to 4 times if recommended by a doctor)
  • 12 months to 5 years – 1 sachet (taken up to 4 times a day if recommended by a doctor)
  • 1 to 11 months – half to 1 sachet a day

Children under 12 do not need take all of the drink at one time. They can take half in the morning and half in the evening.

Faecal impaction

A doctor will tell you if you have faecal impaction and they will advise you on how much to take.

The usual dose for faecal impaction for adults and children over 12 years old:

  • full-strength powder sachets (contains around 13g of macrogol) – 4 sachets on first day, then increase by 2 sachets a day, maximum 12 sachets a day, taken in divided doses
  • half-strength powder sachets (contains around 6g of macrogol) – 8 sachets on first day, then increase by 4 sachets a day, maximum 16 sachets a day, taken in divided doses

The usual dose of paediatric sachets for faecal impaction for children aged:

  • 6 to 11 years – 4 sachets on first day, then increase by 2 sachets a day
  • 12 months to 5 years – 2 sachets on first day, then 4 sachets a day for 2 days, then 6 sachets a day for 2 days, then 8 sachets a day
  • 1 to 11 months – half to 1 sachet once a day


Only give macrogol to children under 12 years old if a doctor has prescribed it.

How to take it

How you take macrogol depends on what type you are taking. If you're not sure which macrogol you have and how to take it, read the information in the packet or speak to a pharmacist.

Ready-to-drink sachets

Drink the contents straight from the packet.

Powder sachets

Dissolve each sachet in 125ml (1/4 pint) of water and stir well, then drink. These are usually flavoured, but if you or your children do not like the flavour, you can add fruit squash to the drink and the medicine will still work properly.

Never swallow the powder without water. If you have severe faecal impaction, it's important to drink extra fluids (water if possible) every day as well as your usual amount.

It's also important with faecal impaction for you (or a child over 12 years old) to drink the daily dose within a 6-hour period. If your child is under 12 years of age, make sure they drink the full daily dose within 12 hours.

Liquid (in a bottle)

You need to dilute the liquid before drinking it.

Open the bottle and measure 25ml (or five 5ml spoonfuls). If you do not have a 5ml medicine spoon ask a pharmacist for one, do not use a kitchen teaspoon as it will not give the right amount.

Pour this into half a glass of water (100ml). Stir well until all the liquid has been evenly mixed and it looks clear, then drink it.

Make sure you or your child finish the whole drink. You can drink it in one go or sip it over 30 minutes. It might help to use a straw. You can make the mixture in advance if you need to take it to work or school.

What if I forget to take it?

If you forget a dose of macrogol, 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.

If a doctor has told you to take macrogol every day and you often forget doses, it may help to set an alarm to remind you. You could also ask a pharmacist for advice on other ways to help you remember to take your medicine.

What if I take too much?

Taking an extra dose of macrogol by accident is unlikely to harm you. You may get diarrhoea and stomach pain but this should ease within a day or two. If it does not, stop taking macrogol and wait for the diarrhoea and stomach pain to pass.

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

5. Side effects

Like all medicines, macrogol 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:

  • diarrhoea
  • indigestion
  • stomach pain (rumbles or aches)
  • bloating and wind (farting and burping)
  • feeling or being sick (nausea or vomiting)
  • sore bottom (anus)

These side effects usually get better if you reduce the amount of macrogol or after you have had a poo. Talk to a doctor or pharmacist if the side effects bother you or do not go away.

Serious side effects

Call a doctor straight away if these rare but serious side effects happen to you:

  • severe diarrhoea or vomiting
  • feeling more tired than usual
  • shortness of breath
  • swollen ankles, feet or legs (oedema)
  • muscle weakness
  • irregular heartbeat

These side effects might mean that there have been changes in the electrolytes in your blood. A doctor can check this with an electrolyte test.

Serious allergic reaction

In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to macrogol.

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 macrogol. For a full list see the leaflet inside your medicines packet.


You can report any suspected side effect to the UK safety scheme.

6. How to cope with side effects

What to do about:

  • diarrhoea – drink lots of fluids, such as water or squash, to avoid dehydration. Signs of dehydration include peeing less than usual or having dark strong-smelling pee. Reducing your dose of macrogol may also help diarrhoea. Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.
  • indigestion – try taking macrogol after food. Talk to a doctor if symptoms do not go away. If you need something to ease the discomfort, try taking an antacid, but do not put off speaking to a doctor.
  • stomach pain – try to rest and relax. It can help to eat and drink slowly and have smaller and more frequent meals. Putting a heat pad or covered hot water bottle on your stomach may also help. If you are in a lot of pain, speak to a pharmacist or doctor.
  • bloating and wind – take macrogol between meals instead of before or after them. Steer clear of foods that cause wind like lentils, peas, beans and onions. It might also help to eat smaller and more frequent meals, eat and drink slowly, and exercise regularly. Some pharmacy remedies help wind, such as charcoal tablets or simeticone.
  • feeling or being sick – try taking macrogol with meals, or mixing your dose with some water or fruit juice. Drink lots of fluids, such as water or squash. If you're being sick, take small, frequent sips to avoid dehydration. Do not take any other medicines without speaking to a pharmacist or doctor.
  • sore bottom (anus) – wash your bottom after each poo and pat it dry with a soft, clean towel.

7. Pregnancy and breastfeeding

Macrogol is generally safe to take during pregnancy and while breastfeeding. Constipation is common at the end of pregnancy and just after having a baby.

If you're pregnant or breastfeeding, it's always better to try to safely treat constipation without taking a medicine.

A doctor or midwife will first advise you to eat more fibre (like potatoes, high-fibre cereals, wholemeal bread, brown rice or wholewheat pasta, fruit and vegetables) and drink plenty of fluids. You'll also be encouraged to do gentle exercise.

If dietary and lifestyle changes do not work, you may be recommended a laxative such as macrogol.

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


Tell a pharmacist or doctor if you're trying to get pregnant, are already pregnant or if you're breastfeeding.

8. Cautions with other medicines

Some medicines, such as epilepsy medicines like phenytoin, may not work as effectively if you use macrogol at the same time.

Mixing macrogol with herbal remedies and supplements

There are no known problems mixing macrogol with herbal remedies or supplements.


For safety, tell a doctor or pharmacist if you're taking any other medicines, including herbal remedies, vitamins or supplements.

9. Common questions

How does macrogol work?

Macrogol is known as an "osmotic" laxative. This means it draws water from the rest of the body into your bowel to make your poo slightly bigger and softer.

It then triggers your bowels to start working to push the poo out.

How long does it take to work?

Macrogol can take 1 to 2 days to start working.

Talk to a doctor if you are still constipated after 3 days.

How long will I take macrogol for?

You can take macrogol for as long as the constipation lasts, or for as long as the doctor has recommended. This will usually be for up to 2 weeks.

The doctor may recommend that you take it for many months if you or your child has serious constipation or take medicines that cause constipation.

Usually for long-term treatment, the dose can be lowered to either 1 or 2 sachets a day.

For faecal impaction, you'll usually only need to take macrogol for up to 3 days, but you may be given a lower dose to take for a little longer.

Is it safe to take macrogol for a long time?

Ideally, you should only take macrogol occasionally and for a few days at a time.

Using laxatives like macrogol for longer can lead to prolonged diarrhoea. 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.

In some people, an electrolyte imbalance can cause serious health problems such as muscle spasms, twitching and fits (seizures).

However, sometimes a doctor may recommend you or your child take macrogol for a few months. This could be because you keep getting constipation or you take medicines that make you constipated. If this happens, the doctor will decide how long and how much macrogol you need to take.

What will happen if I stop taking it?

Usually, it's best to only take macrogol when you have constipation. You can stop taking it for short-term constipation if you are going to the toilet as normal.

If you stop taking it, your constipation might come back.

How does it compare with other laxatives?

There are other types of laxatives. Some work in a different way to macrogol but are equally good at treating constipation. Some work more quickly than macrogol.

  • 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.
  • Stimulant laxatives, such as senna and bisacodyl. These speed up your bowels by stimulating the nerves that control the muscles lining your gut. They work more quickly than other laxatives. If you take them at bedtime, they work overnight.
  • Surface-wetting laxatives, such as arachis oil and docusate sodium. These let water get into poo to soften it and make it easier to pass.
Can I take different laxatives together?

For most people, 1 laxative will be enough to relieve constipation.

Occasionally, you may need to take 2 different types of laxatives at the same time.

Only take 2 laxatives together if a doctor recommends it as there's more risk of getting side effects.

Will it affect my contraception?

Macrogol does not affect any type of contraception including the combined pill or 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 being sick or have diarrhoea.

Will it affect my fertility?

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

Can I drive or ride a bike?

Yes, macrogol has no effect on driving, riding a bike or using machinery.

Is there any food and drink I need to avoid?

You can eat and drink normally while taking macrogol.

It might be a good idea to stop eating pastries, puddings, sweets, cheese and cake for a while as these foods can make constipation worse.

Can I drink alcohol with it?

Yes, you can drink alcohol with macrogol.

Can lifestyle changes help constipation?

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

  • get more fibre into your diet – aim for about 30g of fibre a day. High-fibre foods include fruit, vegetables and cereals. If you are 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

Page last reviewed: 28 October 2019
Next review due: 28 October 2022