Laxatives are a type of medicine that can help you empty your bowels if you're having trouble going to the toilet.

They're widely used to treat constipation if lifestyle changes, such as increasing the amount of fibre in your diet, drinking plenty of fluid and taking regular exercise, haven't helped.

Laxatives are available over-the-counter, without a prescription, from pharmacies and supermarkets.

This topic covers:

Types of laxatives

Which laxative should I use?

Things to consider

How to take laxatives

How long should laxatives be used for?

Side effects


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 them retain fluid, encouraging your bowels to push the stools out
  • osmotic laxatives – such as lactulose and polyethylene glycol, which soften your stools and make them 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's a lack of high-quality evidence about exactly how effective they are and whether certain laxatives are better than others.

Unless there's 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 are still difficult to pass, try taking a stimulant laxative in addition to a bulk-forming laxative.

Osmotic laxatives usually start to work after about two or three days, while stimulant laxatives usually have an effect within six to 12 hours.

Speak to your GP or pharmacist if you're unsure which laxative to use. Also see your GP if you're still constipated after trying all of the different types of laxative, or if you think your child might benefit from taking laxatives.

Things to consider

Although laxatives are available over-the-counter, they're not suitable for everyone.

Laxatives aren't 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, carefully read the patient information leaflet that comes with the medication to make sure it's safe for you to take.

Read more about the considerations regarding laxatives.

How to take laxatives

How you take laxative medication depends on the form it comes in, they 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 back passage

Some laxatives are also designed to be taken at certain times of the day, such as first thing in the morning or last thing at night.

Read the patient information leaflet that comes with your medication so you know how to take it properly. Ask your pharmacist for further advice if you're still not sure how to take your medication.

While taking bulk-forming or osmotic laxatives it's particularly important to stay well hydrated by drinking plenty of fluids. This is because these laxatives can cause dehydration.

Never take more than the recommended dose of laxatives because this can be harmful and 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. Stop taking a laxative when your constipation improves.

After taking a laxative, to help stop constipation returning you can make certain lifestyle changes, such as drinking plenty of water, exercising regularly and including more fibre in your diet. These types of measures are a better way of preventing constipation than excessive use of laxatives.

See your GP for advice if you're often constipated, despite making appropriate lifestyle changes, or if your constipation hasn't improved after taking laxatives for more than a week.

Don't 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).

Side effects

Like most medications, laxatives can cause side effects. They're usually mild and should pass once you stop taking the medication.

The side effects you may experience will depend on the specific medication you're taking, but common side effects of most laxatives include:

  • bloating
  • passing wind (flatulence) 
  • painful tummy (abdominal) cramps
  • feeling sick
  • dehydration – which can make you feel lightheaded, have headaches and pass urine that's darker than normal

Contact your GP for advice if you experience any particularly troublesome or persistent side effects 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.


It's 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 about 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
  • exercising regularly

Read more about preventing constipation.

Reporting side effects

The Yellow Card Scheme allows you to report suspected side effects from any type of medicine you're taking.

It's run by the UK medicines safety watchdog  the Medicines & Healthcare products Regulatory Agency (MHRA).

Page last reviewed: 20/06/2016

Next review due: 20/06/2019