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What does it do?

Lactulose is used to treat and prevent constipation. It is also sometimes used for other conditions.

How should you take it?

Take lactulose as directed with a glass of water. Measure the dose carefully. It can be mixed with fruit juice or water.

What if you forget a dose?

Should an occasional dose be missed it need not be taken later.

Can you take other medicines?

Some medicines available without a prescription may react with lactulose including:

  • other laxatives – discuss this with your pharmacist
  • anti-diarrhoea medicines such as loperamide (e.g. Imodium®)

Tell your pharmacist or doctor about all medicines or treatments that you may be taking, including vitamins, herbal products or recreational drugs.

What side effects might you notice?

Side EffectsRecommended action

Farting, stomach cramps, bloating, diarrhoea, nausea, vomiting

Tell your doctor if troublesome

If you notice any other effects, discuss them with your doctor or pharmacist.

Other information:

  • Tell your doctor if you have heart, kidney, stomach or bowel problems, or need a galactose and/or lactose free diet.
  • Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding.
  • Drink plenty of fluids while taking lactulose.
  • Do not use lactulose for longer than 1 week unless told to by your doctor.
  • If you have noticed a change in bowel habit that continues for longer than 2 weeks, talk to your doctor before taking lactulose.

This leaflet contains important, but not all, information about this medicine.

Prepared by the PILs Committee at Christchurch Hospital, Canterbury District Health Board, New Zealand. September 2017

For more general information about this sheet and its contents, see: What does a My Medicines sheet cover?

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About My Medicines

My Medicines Patient Information Leaflets (PILs) contain important, but not all, information about the medicines they describe.

For more information about the sheets, see: What does a My Medicines sheet cover?

My Medicines is developed by a team at the Canterbury District Health Board. Our team is made up of doctors, pharmacists, and a non-medical person to help us keep to plain language. We also discuss our information with specialist health professionals or groups when needed