What laxatives are for
Laxatives are a type of medicine that help you poo.
They're mainly used:
- to treat difficulty pooing (constipation)
- if you have a condition like an anal fissure, when it helps if your poo is soft or you can poo more easily
- if you have a condition or are taking a medicine that can cause difficulty pooing – you might be prescribed laxatives to make this less likely
They may also be used to make sure your bowels are empty before a scan or procedure, such as a colonoscopy.
For most adults with constipation, it's usually recommended you try lifestyle changes first, before using laxatives.
Find out how you can treat and prevent constipation yourself.
Types of laxative
There are 4 main types of laxative, which work in different ways.
| Type | Medicine name | How they work |
|---|---|---|
|
Type
Bulk-forming laxatives |
Medicine name |
How they work
Increase the fibre in poo to help make it bigger and softer, which triggers your bowel muscles to push it out. They take up to 3 days to work. |
|
Type
Osmotic laxatives |
Medicine name |
How they work
Bring more water from the rest of your body into your bowel so poo is softer, making it easier to push out. They take 2 to 3 days to work. |
|
Type
Poo-softening laxatives (stool softeners) |
Medicine name
|
How they work
Allow more water and fat into poo so it's softer and more slippery, making it easier to push out. They take 12 hours to 3 days to work. |
|
Type
Stimulant laxatives |
Medicine name |
How they work
Trigger your bowel muscles to push poo out. They take 6 to 12 hours to work. |
Not all laxatives are listed here. If you cannot find your medicine, check the leaflet that comes with your laxative, or ask a pharmacist or your doctor.
Which type of laxative to try first
If you're buying laxatives without a prescription, it's usually best to try a bulk-forming laxative first.
If this does not work for you or you're not sure what type to try, a pharmacist can help. Try not to be embarrassed. They will be used to talking about these symptoms.
How to use laxatives
Laxatives may come as:
- tablets, capsules or liquid you swallow
- liquid or packets of powder you mix with water and then drink
- medicine you put into your bottom where it dissolves (suppositories)
- liquids or gels you put inside your bottom (enemas)
Some laxatives may need to be taken at a certain time of day. The instruction leaflet that comes with your medicine will explain how and when to take it.
If you're taking bulk-forming or osmotic laxatives, it's important to drink plenty of fluids to avoid dehydration.
Important
If you bought laxatives without a prescription, stop taking them when your constipation improves and do not take them for longer than 7 days.
If you've used laxatives for 3 days and they have not helped, speak to a doctor or pharmacist.
Side effects of laxatives
Like all medicines, laxatives can cause side effects.
Common side effects
Any side effects you may get depend on the type of laxative you're taking, but common side effects of most laxatives include:
- farting
- bloating
- stomach pain and cramps
- feeling sick (nausea) or being sick (vomiting)
- diarrhoea
These side effects are usually mild and should stop once you stop taking the laxative.
Serious side effects
If you use laxatives too often or for too long, they can cause problems such as:
- an allergic reaction (anaphylaxis) – causing symptoms such as a swollen throat or tongue, a raised and itchy rash, and difficulty breathing
- dehydration – causing symptoms such as headaches, feeling light-headed and pee that's darker than normal
- a blockage in your bowel (intestinal obstruction)
- low potassium in your blood – causing symptoms such as muscle weakness, tiredness, needing to pee a lot and heart rhythm problems
This is not a full list of all the possible side effects of laxatives. Check the information leaflet that comes with your medicine to find out more.
Who can take laxatives
Most adults can take laxatives.
Check with a pharmacist or doctor before taking laxatives if you:
- have ever had an allergic reaction to a laxative – this can include a skin rash, or swelling of the face and throat
- are pregnant or breastfeeding
- have a heart condition, such as heart failure
- have difficulty swallowing
- have a digestive a condition, like Crohn's disease or ulcerative colitis
- have a lactose intolerance – some laxatives contain lactose
- are taking opioid painkillers, such as codeine or morphine
You can usually still use laxatives, but some types might not be suitable for you. Always check the packet or leaflet that comes with the medicine.
Babies and children can take laxatives if recommended by a GP.
Constipation in children
Speak to a GP if you think your child is having difficulty pooing. Find out more about constipation in children.
Page last reviewed: 30 April 2026
Next review due: 30 April 2029