Macrogol (for constipation)

Sounds like 'mak-roe-gol'

Easy-to-read medicine information about macrogol – what it is, how to take macrogol safely and possible side effects.

Type of medicine Also called
  • Laxative
  • Osmotic laxative
  • Molaxole
  • Movicol

What is macrogol?

Macrogol is a type of laxative that helps to produce a soft bowel motion (poo). It is used to treat and prevent constipation. It can also be used for relief of very bad constipation, called faecal impaction. Read more about constipation in adults and constipation in children.

There are many different types of laxatives. Macrogol is referred to as an osmotic laxative, which means that it works by drawing water into the bowel. The bowel becomes filled with extra fluid, which stimulates the muscles of the walls of the bowel to contract and squeeze the poo along, causing a bowel motion. Read more about types of laxatives.

In New Zealand, macrogol comes in sachets of powder, which need to be dissolved in water. Examples include Molaxole and Movicol. 

Dose of macrogol

The dose of macrogol will be different for different people depending on how severe their constipation is and their age. 

  • Some people will be advised to take macrogol for a few days only to relieve constipation while others may be advised to use it regularly, every day to prevent constipation.  
  • Your doctor will develop a plan that tells you how many sachets of macrogol to use in a day. They will explain how to adjust the plan so that you have regular soft poos and will also tell you the maximum number of sachets that you can have in one day.
  • If you are unsure of your dose and how much to take, ask your doctor or pharmacist for advice.   

How to take macrogol

Dissolve each sachet in water as directed before taking. Macrogol must be given with water. Follow the instructions on the amount of water to be used – usually, this is at least 125 mL (about half a glass of water) per sachet. If you are unsure about how to use the sachets, ask your pharmacist for advice. 

Some handy tips

  • Drink enough water: If you do not drink enough water with it, the medicine will not work properly and you may become dehydrated.
  • Stir well: stir the contents of the sachet in water. Mix well until all the powder has dissolved and the mixture is clear or slightly hazy.
  • Improve the taste: you can add orange squash to the drink if you don’t like the taste. The medicine will still work properly. Using water that is slightly chilled may be helpful or try drinking the mixture through a straw.

When should the medicine start working?

It may be a few hours, or sometimes a day or more before you have a bowel motion (poo). This will depend on how bad the constipation is and its cause. Your doctor may give you a plan to give more sachets in a day if the macrogol does not appear to be working at first.

Precautions — before taking macrogol

  • Do you have heart problems?
  • Do you have other stomach or bowel problems?
  • Are you pregnant or breast-feeding?

If so, it’s important that you tell your doctor before you start taking macrogol. Sometimes a medicine isn’t suitable or it can only be used with extra care.  

Possible side effects

Like all medicines, macrogol can cause side effects, although not everyone gets them. Often side effects improve as your body adjusts to the new medicine.

Side effects What should I do?
  • Stomach discomfort
  • Tummy ache
  • Bloating (wind or gas)
  • Diarrhoea (very runny poos)
  • Tell your doctor if troublesome.
  • Signs of dehydration such as feeling weak, very thirsty and headache,
  • Tell your doctor 

Learn more

The following links have more information on macrogol. 

Macrogol  (adults) New Zealand Formulary
Macrogol (children) New Zealand Formulary
Macrogol for constipation and disimpaction in children Waitemata DHB

References

  1. Macrogols (laxative) New Zealand Formulary
  2. Macrogols (laxative) New Zealand Formulary for Children
  3. Managing constipation in older adults BPAC, 2019
Credits: Sandra Ponen, pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 30 Jul 2019