Lactulose
NHS information about the medicine lactulose, including what it's used for, who can take it, how to take it and side effects.
What lactulose is for
Lactulose is used to treat:
- constipation (problems pooing), such as not pooing very often or having poo that's dry and hard
- a liver condition called hepatic encephalopathy
Lactulose is a type of medicine called an osmotic laxative.
It works by bringing water into your bowel to help soften your poo and make it easier to push out.
How to take lactulose
Lactulose comes as a liquid (oral solution) that you drink.
How often and how long you take it for depends on why you're taking it. Always follow the advice your doctor or pharmacist gives you.
It can take 2 to 3 days to start working.
When taking lactulose:
- use the spoon or cup that comes with your medicine to measure the correct dose
- drink plenty of fluid to stay hydrated – being hydrated also helps with constipation
- try to take it at the same times each day and space the doses evenly
- you can take it with or without food
- you can add extra flavouring to make it taste nicer, such as squash
Always check the packet or leaflet that comes with your medicine. Ask a pharmacist or doctor for advice if you're not sure how to take it or have any problems taking it.
Side effects of lactulose
Like all medicines, lactulose can cause side effects, although not everyone gets them.
Common side effects
Common side effects of lactulose include:
- farting – this should ease after a few days
- bloating
- stomach ache
- feeling sick (nausea) or being sick (vomiting)
- diarrhoea
Lactulose does not usually affect your ability to drive, ride a bike or use machinery.
More about serious side effects
These are not all the side effects of lactulose.
For a full list, see the leaflet that comes with your medicine or search for your medicine leaflet on the electronic medicines compendium website.
You can report any side effects you get on the Yellow Card website
Who can and cannot take lactulose
Most adults and children aged 14 years and over can take lactulose. Babies and children younger than 14 years can only have lactulose if it's prescribed by a doctor.
But lactulose is not suitable for everyone. For example, it may not be suitable if:
- you've had an allergic reaction or serious side effect from lactulose or a similar medicine before
- you're lactose intolerant, allergic to the sugars galactose or fructose, or have a rare condition called galactosaemia
- you have a bowel condition such as irritable bowel syndrome, diverticular disease or Crohn's disease, or a blockage in your bowel that is not from constipation
- you have diabetes and are taking lactulose for hepatic encephalopathy – high doses of lactulose can affect your blood sugar (glucose) levels
Check the packet or leaflet that comes with your medicine to see if it's suitable for you or your child. Speak to a pharmacist or doctor if you're not sure if you can take it.
Breastfeeding and lactulose
You can take lactulose while breastfeeding.
It's rare for breastfed babies to get any side effects from medicine you're taking, but speak to a healthcare professional if you have any concerns about your baby.
Pregnancy and lactulose
You can take lactulose if you're pregnant, but it's best to speak to a pharmacist or doctor first.
Taking lactulose with other medicines, food and drink
There are some medicines, remedies and supplements that may not mix well with lactulose.
Before you take lactulose, check the packet or leaflet that comes with the medicine to see if it's suitable for you. Speak to a pharmacist or doctor if you're not sure if you can take it.
Food, drink and alcohol with lactulose
You can eat and drink as normal while taking lactulose.
It's important to drink plenty of fluid when taking lactulose to avoid dehydration.
Find out more about your medicine
To find out more about your medicine, you can:
- check the leaflet that comes with it
- read about lactulose for constipation on the Medicines for Children website
- search for your medicine leaflet on the electronic medicines compendium website
- speak to a pharmacist for advice
