> Western Medicines > Macrogol


Used for: Constipation, Bowel cleansing prior to colonoscopy
Chinese name:

What is Macrogol for?

Macrogol, also known as PEG or Polyethylene Glycol, is a laxative to treat constipation. It works by drawing water from the gut and softening stools, therefore stimulating bowel movement and relieving constipation. Macrogol is used to prepare the bowels before colonoscopy or other bowel procedures.

How to use it?

Macrogol is available as powders which are taken orally to stimulate bowel movement. There are two formulations, Macrogol 3350 and Macrogol 4000 powder. The powder should be dissolved in a cup of water (around 120-240 ml). You may also use juice, soda, coffee or tea. Drink the solution within 30 minutes. It usually takes 1-2 days to trigger bowel movements.


If you use Macrogol 4000 powder, take 10-20 g once daily for constipation. If you use Macrogol 3350 powder, take 17 g once daily initially, and may increase to twice daily if constipation is not relieved. Do not use it for more than 1 week.


For children under 12 years, the dosage for constipation varies according to age and the formulation. Do not use Polyethylene Glycol for more than 3 months.


As Macrogol 4000:
Child over 8 years
Initially 10 g every other day, and may increase to 20 g once daily if constipation is not relieved.


As Macrogol 3350:
Child 6-12 years
17 g once daily, which may increase or decrease according to response. Maximum is 25.5 g daily.

Children 4-5 years
Initially 8.5 g once daily, and may increase to a maximum of 17 g once daily if constipation is not relieved.

What are the side effects of Macrogol?

Common side effects of Macrogol include indigestion, diarrhoea, stomach pain, flatulence and soreness in the anus.

Who should not take Macrogol?

People allergic to Macrogol or any component of the formulation

Pharmacist Tips:

  • Drink more water, increase fiber intake and exercise regularly to ensure soft bowel movement and reduce straining.
  • If you find dark-colour blood in your stool, along with abdominal pain, vomiting, or diarrhoea, please seek medical attention immediately.
  • Report to your doctor or pharmacist if constipation does not resolve after using this medicine.


Common dosing schedule:
Use once or twice daily.

This schedule is for reference only, adjustments may be made according to individual needs.


Some common medications Macrogol may interact with:

Please notify your doctor or pharmacist if you are taking the above medication, dosage adjustments might be needed.

Where to buy Macrogol in Hong Kong?

In Hong Kong, Macrogol is an over-the-counter medicine and 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 https://www.drugoffice.gov.hk

Need more information?

For detailed information about the use of Macrogol 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.

Brands in Hong Kong
Available dosage
  • 10g (Sachets)
Drug class
Sub class
Osmotic Laxatives
Alternative Names
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