Senna
Also known as: Senokot
What it's for
Senna is a stimulant laxative for constipation. It makes your bowel muscles contract to push stool out. It usually works within 8 to 12 hours.
Comes as: Tablets or liquid
How to take it
- Adults: Usually 1 or 2 tablets at bedtime.
- It usually works within 8 to 12 hours.
- Take in the evening to work overnight.
- Do not use for more than a week without advice.
Doses here are typical. Always follow the instructions from your prescriber or on the packet — they come first.
Common side effects
- Stomach cramps
- Your urine may turn slightly red or brown (harmless)
The leaflet inside the packet lists all known side effects.
Important safety points
- Do not use every day long-term - your bowel can become dependent
- Not for use if you have stomach pain, nausea, or vomiting
- Drink plenty of fluids
- If constipation persists, see your doctor
Get medical help urgently if…
- You have severe stomach pain
- You have blood in your stool
- You have been constipated for more than a week despite treatment
- You have nausea or vomiting with constipation
Call NHS 111 for urgent advice, or 999 if someone is seriously unwell.
Before you act on anything here
This page is general information, written to help you understand — it is not personal medical advice and it cannot tell you what is right for you. Talk to your own GP, pharmacist or nurse about your own health.
- Need help now but it's not an emergency? Call NHS 111 or use 111.nhs.uk.
- Emergency? Call 999 or go to A&E.