Senna
NHS information about the medicine senna, including what it's used for, who can take it, how to take it and side effects.
What senna is for
Senna is used to treat constipation (problems pooing), such as not pooing very often or having poo that's dry and hard.
Senna is a type of medicine called a stimulant laxative. It works by triggering your bowel muscles to push poo out.
How to take senna
Senna comes as tablets or a liquid (syrup) that you swallow.
You take it once a day, usually in the evening before bed. It takes around 8 to 12 hours to work.
When taking senna:
- start with the lowest dose and increase it gradually if this does not work – speak to a doctor or pharmacist if you're not sure how much to take
- swallow tablets whole, with a drink of water
- use the spoon or cup that comes with the liquid medicine to measure the correct dose
Always check the packet or leaflet that comes with your medicine. Ask a pharmacist or doctor for advice if you're not sure how to take it or have any problems taking it.
Side effects of senna
Like all medicines, senna can cause side effects, although not everyone gets them.
Possible side effects of senna include:
- stomach pain, cramps or discomfort
- diarrhoea
- yellow-brown or red-brown pee – this is harmless and will stop once you stop taking senna
Senna does not usually affect your ability to drive, ride a bike or use machinery.
More about serious side effects
These are not all the side effects of senna.
For a full list, see the leaflet that comes with your medicine or search for your medicine leaflet on the electronic medicines compendium website.
You can report any side effects you get on the Yellow Card website
Who can and cannot take senna
Most adults and children aged 12 years and over can take senna. Children younger than 12 years can only have senna if it's prescribed by a doctor.
But senna is not suitable for everyone. For example, it may not be suitable if:
- you've had an allergic reaction or serious side effect from senna or another laxative before
- you have a bowel condition such as irritable bowel syndrome, diverticular disease or Crohn's disease, or a blockage in your bowel that is not from constipation
- have kidney or heart problems
Check the packet or leaflet that comes with your medicine to see if it's suitable for you or your child. Speak to a pharmacist or doctor if you're not sure if you can take it.
Breastfeeding and senna
You can take senna while breastfeeding, if your baby is aged 1 month or older.
It's rare for breastfed babies to get any side effects from medicine you're taking, but speak to a healthcare professional if you have any concerns about your baby.
Pregnancy and senna
You can usually take senna if you're pregnant, but it's best to speak to a pharmacist or doctor.
They may suggest making changes to your diet or lifestyle, or trying a different type of laxative first.
Taking senna with other medicines, food and drink
There are some medicines, remedies and supplements that may not mix well with senna.
This includes:
- some types of heart medicine, such as medicines for heart failure or heart rhythm problems
- medicines to make you pee more (diuretics)
- steroids
- anything made with liquorice root, such as supplements or liquorice tea
Before you take senna, check the packet or leaflet that comes with the medicine to see if it's suitable for you. Speak to a pharmacist or doctor if you're not sure if you can take it.
Food, drink and alcohol with senna
You can mostly eat and drink as normal while taking senna, but avoid anything made with liquorice root.
Find out more about your medicine
To find out more about your medicine, you can:
- check the leaflet that comes with it
- read about senna for constipation on the Medicines for Children website
- search for your medicine leaflet on the electronic medicines compendium website
- speak to a pharmacist for advice
