Used for: Constipation
Chinese name:

What is Senna for?

Senna is a medicine that is derived from the senna plant. It belongs to a class of medications called stimulant laxatives, which can stimulate a bowel movement by increasing the activity of the intestines. Senna is therefore used for treating constipation.


Sennosides can be found in Senna and they are activated by the bacteria in the colon. It takes 6-12 hours for Senna to work and hence it is preferred to take Senna at bedtime in order to have a bowel movement the next morning.

How to use it?

Senna can be taken by mouth as tablets. For adults, you should take 7.5-15 mg daily at bedtime, start at a low dose and increase gradually. The maximum dose is 30 mg daily but higher doses may be prescribed by doctors. For children between 6 and 17 years old, the dose should be 7.5-30 mg once daily and adjusted according to their response.

What are the side effects of Senna?

Common side effects of Senna include abdominal cramps and diarrhoea.

Who should not take Senna?

Senna is generally safe for pregnancy and lactation.

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Where to buy Senna in Hong Kong?

In Hong Kong, Senna 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

Need more information?

For detailed information about the use of Senna 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
  • 7.5mg (Tablets)
Drug class
Sub class
Stimulant Laxatives
Other drugs in same class
Used for: Constipation
Chinese name:
Used for: Constipation
Chinese name:
Used for: Constipation
Chinese name:
Fleet Enema
Used for: Constipation, Bowel cleansing prior to colonoscopy
Chinese name:
Used for: Bowel cleansing prior to colonoscopy
Chinese name: