Medicines & Supplements A to Z > Lactulose


Last updated on July 3, 2019.

Overview   |   Dosage   |   Side Effects   |   Where To Buy  



COMMON BRANDS IN HONG KONG: Danilax 丹尼通, Dhactulose, Duphalac

What is Lactulose for?

Lactulose is a man-made sugar that is used as a laxative. It works by drawing water into your bowel and softening your stools, making them easier to be removed from your body. Lactulose is used to treat constipation and hepatic encephalopathy. The taste of lactulose is very sweet and you can dilute it with water, milk or fruit juice to make it more palatable. Lactulose usually begins working within 1-2 days.

How to use it?

Lactulose can be taken by mouth as syrup or solution. The doses for different age groups are listed below but they are not absolute and should be adjusted according to you or your child’s response: 


Start with 15 mL twice daily. 

Child 1-11 months 

2.5 mL twice daily. 

Child 1-4 years 

2.5-10 mL twice daily. 

Child 5-17 years 

5-20 mL twice daily.

What are the side effects of Lactulose?

Common side effects of Lactulose include abdominal pain, diarrhoea, flatulence, nausea and vomiting.

Where to buy Lactulose in Hong Kong?

In Hong Kong, Lactulose is an over-the-counter medicine which can be purchased without a prescription from any retail outlet in Hong Kong. This includes grocery stores, convenience stores, medicine shops, and pharmacies. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health. 

For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at

For detailed information about the use of Lactulose in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.

Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.