Laxatives are a type of medicine that can help you empty your bowels if you are having trouble going to the toilet.
They are widely used to treat constipation if lifestyle changes (see below) haven't helped. They are available over-the-counter, without a prescription, from pharmacies and supermarkets.
Types of laxatives
The main laxatives used in the UK are:
bulk-forming laxatives, such as ispaghula husk and methylcellulose, which work in the same way as dietary fibre – they increase the bulk of your stools (faeces) by helping your stools retain fluid, encouraging your bowels to push the stools out
osmotic laxatives, such as lactulose and polyethylene glycol, which make your stools softer and easier to pass by increasing the amount of water in your bowels
stimulant laxatives, such as bisacodyl, senna and sodium picosulfate, which speed up the movement of your bowels by stimulating the nerves that control the muscles lining your digestive tract
stool softener laxatives, such as arachis oil and docusate sodium, which increase the fluid content of hard, dry stools, making them easier to pass
There are also a number of alternative laxatives that are less commonly used, including bowel cleansing solutions, peripheral opioid-receptor antagonists, linaclotide and prucalopride.
Which laxative should I use?
Although laxatives have been around for a long time, there is a lack of high-quality evidence about exactly how effective they are and whether certain laxatives are better than others.
Unless there is a reason why specific laxatives may be more suitable than others (see below), most adults should try using a bulk-forming laxative first. These usually start to work after about two or three days.
If your stools remain hard, try using an osmotic laxative in addition to – or instead of – a bulk-forming laxative. If your stools are soft, but you still find them difficult to pass, try taking a stimulant laxative in addition to a bulk-forming laxative.
Osmotic laxatives usually start to work after about 2 or 3 days, while stimulant laxatives usually have an effect within 6 to 12 hours.
If you are unsure which laxative you should take, speak to your GP or pharmacist for advice. You should also see your GP if you are still constipated after trying all of these types of laxative, or if you think your child might benefit from taking laxatives.
Things to consider
Although laxatives are available over-the-counter, this does not mean they are suitable for everyone.
Laxatives are not usually recommended for children, unless advised by a doctor, and some types of laxatives may not be safe to use if you have certain conditions, such as Crohn’s disease or ulcerative colitis.
Before using laxatives, you should carefully read the patient information leaflet that comes with the medication, to make sure it is safe for you to take.
How to take laxatives
How you take laxative medication depends on the form it comes in. Laxatives are commonly available as:
tablets or capsules you swallow
sachets of powder you mix with water and then drink
suppositories – a capsule you place inside your back passage (rectum), where it will dissolve
liquids or gels that you place directly into your rectum
Some laxatives are also designed to be taken at certain parts of the day – such as first thing in the morning or last thing at night.
Make sure you carefully read the patient information leaflet that comes with your medication, so you know how to take it properly. If you are not sure how to take your medication, ask your pharmacist for advice.
While you are taking bulk-forming or osmotic laxatives, it is particularly important to stay well hydrated by drinking plenty of fluids. This is because these laxatives can cause dehydration.
Never take more that the recommended dose of laxatives, as this can be harmful and can cause troublesome side effects (see below).
How long should laxatives be used for?
Ideally, laxatives should only be used occasionally and for short periods of time. You should stop taking a laxative when your constipation improves.
After taking a laxative, you can help stop constipation returning by making certain lifestyle changes, such as drinking plenty of water, exercising regularly and including more fibre in your diet. Measures such as this are a better way of preventing constipation than excessive use of laxatives.
See your GP for advice if you are often constipated, despite making appropriate lifestyle changes, or if your constipation hasn't improved after taking laxatives for more than a week.
Do not get into the habit of taking laxatives every day to ease your constipation, because this can be harmful.
In some cases, you may be prescribed a laxative to use regularly, but this should always be supervised by your GP or a gastroenterologist (a specialist in digestive conditions).
Possible side effects
Like most medications, laxatives can cause side effects. These are usually mild and should pass once you stop taking the medication.
The specific side effects you may experience depend on the exact medication you are taking, but common side effects of most laxatives include:
passing wind (flatulence)
painful tummy (abdominal) cramps
dehydration – which can make you feel lightheaded, experienceheadaches and pass urine that is a darker colour than normal
Contact your GP for advice if you experience any particularly troublesome or persistent symptoms while taking laxatives.
Excessive or prolonged use of laxatives can also cause diarrhoea, intestinal obstruction (where the bowel becomes blocked by large, dry stools) and unbalanced levels of salts and minerals in your body.
For more information about the side effects related to your medication, check the patient information leaflet that came with it or look up your medicine in the Medicines A-Z.
It is often possible to improve constipation without having to use laxatives. Before trying laxatives, it may help to make a number of lifestyle changes, such as:
increasing your daily intake of fibre – you should eat at least 18-30g of fibre a day; high-fibre foods include fruit, vegetables and cereals
adding bulking agents, such as wheat bran, to your diet – these will help make your stools softer and easier to pass, although bran and fibre can sometimes make bloating worse
drinking plenty of water
Considerations when using laxatives
Most people can use laxatives, although not every type is suitable for everyone.
For example, you should check with your GP or pharmacist before using laxatives if:
you have a bowel condition, such as irritable bowel syndrome (IBS), Crohn’s disease or ulcerative colitis
you have a colostomy or ileostomy (where the small or large intestine is diverted through an opening in the abdomen)
you have a history of liver or kidney disease
you are pregnant or breastfeeding
you have an obstruction somewhere in your digestive system
you have diabetes, as some laxatives can lead to a rise in blood sugar levels, which could be dangerous for a person with diabetes
you have difficulties swallowing (dysphagia)
you have a lactose intolerance, as some laxatives contain lactose
you have phenylketonuria (a rare genetic condition, where the body cannot break down a substance called phenylalanine), as phenylalanine is found in certain bulk-forming laxatives
you are taking opioid painkillers, such as codeine or morphine
These situations don't usually mean you can't use laxatives, but they may mean certain types of laxative are more suitable for you than others.
Children and laxatives
Laxatives are not recommended for babies who have not yet been weaned. If they are constipated, try giving them extra water in between feeds. Gently massaging a baby's tummy and moving the legs in a cycling motion may also help.
Babies who are eating solid foods may be able to use laxatives, but you should first make sure your child drinks plenty of water or diluted fruit juice and increase the amount of fibre in their diet. If your child is still constipated, your GP may prescribe or recommend a laxative.
In older children, osmotic or stimulant laxatives are often recommended alongside changes to diet as the first treatment for constipation.
You should always check with your GP before giving your baby or child a laxative.
Try natural methods first
In adults, constipation can often be relieved by:
by drinking more water
doing more exercise
including more fibre in your diet
If possible, try these simple steps before using laxatives.