Dosage
Your dose of lactulose can go up or down, depending on how well the medicine is working.
The usual dose for constipation is:
- adults – 15ml, taken twice a day as a starting dose
- children aged 5 to 17 years – 5ml to 20ml, taken twice a day
- children aged 1 to 4 years – 2.5ml to 10ml, taken twice a day
- babies aged 1 month to 11 months – 2.5ml, taken twice a day
For adults with hepatic encephalopathy, the usual dose is between 30ml and 50ml, taken 3 times a day.
Important
Only give lactulose to a child under 14 years if their doctor recommends it.
How to take it
You can take lactulose with or without food.
The medicine comes with a plastic cup or spoon to measure your dose. If you do not have a cup or spoon, ask your pharmacist for one. Do not use a kitchen spoon as it will not measure the right amount.
Some people do not like the sweet taste of lactulose. To improve the taste, you can mix your dose with half a glass or water or fruit juice.
Aim to drink 6 to 8 glasses of water or other liquid during the day while you're taking lactulose or your constipation may get worse.
How long to take it for
You can take lactulose for as long as your constipation lasts, or for as long as your doctor has recommended. This will usually be for up to a week.
For more severe constipation, and if you're taking lactulose for hepatic encephalopathy, your doctor may recommend that you take it for many months.
If you forget to take it
If you forget a dose of lactulose, just skip the missed dose and take your 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 your doctor has told you to take lactulose every day and you often forget doses, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicine.
If you take too much
Taking an extra dose of lactulose 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.