Expert reviewer, Shabina Azmi, Pharmacist
Next review due August 2022

Laxatives are medicines that help you poo more easily or more regularly. You can use them to ease constipation or to empty your bowels before a medical procedure.

Two people reading instructions on a medicine container

Uses of laxatives

Your GP or pharmacist may recommend you take laxatives if you have constipation. If you’re constipated, it means you’re finding it harder than usual to poo or you’re not pooing regularly. This can mean different things to different people because pooing habits vary from person to person.

You may need to take laxatives for constipation caused by your lifestyle habits such as not eating enough fibre or being dehydrated. Or you may need laxatives if you have a chronic digestive problem such as irritable bowel syndrome. You may also need to take laxatives if you regularly take medicines such as some opioid painkillers, which could make you constipated.

You may be prescribed laxatives to empty your bowels before surgery. You may also need to take them if you’re having a test to look inside your large bowel, such as a barium enema or colonoscopy.

Not all types of laxative are suitable for everyone. So always check with your GP or pharmacist before taking them, especially if:

  • you’re pregnant or breastfeeding
  • you have an inflammatory bowel disease such as ulcerative colitis
  • you’re very dehydrated
  • you have a heart problem
  • you have diabetes

You shouldn't give laxatives to children unless your doctor has prescribed them. If your child has constipation, take them to their doctor for further information and advice

How laxatives work

Laxatives make it easier for you to poo. They work by either:

  • making your poo bigger or bulkier so it’s easier to push out
  • triggering nerves in your bowel so your bowel muscles move more easily
  • making your poo oilier or softer so it’s easier to push out

Types of laxative

There are several types of laxative – you can buy some of these over the counter from a local store or pharmacy without a prescription or you may be prescribed them by your doctor. Each type of laxative works in a different way to help ease constipation. Your doctor or pharmacist will recommend the best laxative for you and your symptoms.

Bulk-forming laxatives

These work in a similar way to natural fibre – they make your poo more bulky. This triggers your bowel muscles to push your poo out.

Common bulk-forming laxatives include:

  • bran powder
  • ispaghula husk (for example, Fybogel and Ispagel)
  • methylcellulose (for example, Celevac)
  • sterculia (for example, Normacol)

Osmotic laxatives

These increase the amount of water in your bowel, which makes it easier for you to poo.

Common osmotic laxatives include:

  • lactulose (for example, Duphalac)
  • macrogols (for example, Movicol, CosmoCol, Laxido, Molative and Vistaprep)

Stimulant laxatives

These trigger the nerves in your bowel, so your bowel muscles contract to push your poo out.

Stimulant laxatives include

  • senna (for example, Senokot, Potter’s Senna and Sennosides)
  • bisacodyl (for example, Dulcolax, Entrolax, Bisacodyl and Numark Constipation Relief)
  • sodium picosulfate (for example, Dulcolax Pico)

Faecal softener laxatives

These oil and soften your poo so it’s easier to pass.

Faecal softener laxatives include:

  • docusate sodium (for example, DucloEase, Dioctyl and Norgalax)
  • glycerol suppositories

Docusate sodium and glycerol both trigger your bowel muscle nerves too.

Lubricant laxatives

These oil your bowel so your poo passes through it more easily.

Lubricant laxatives include:

  • arachis oil
  • liquid paraffin

Bowel cleansing products

These are used before surgery or a medical procedure to empty your bowel. They’re not used to treat constipation.

Bowel cleansing products include:

  • citric acid with magnesium carbonate (for example, Citramag)
  • sodium acid phosphate with sodium phosphate (for example, Phospho-soda and Cleen Ready-to-use)

Taking laxatives

Laxatives come in many different forms. You can take them as:

  • tablets, syrups or capsules to swallow
  • powders or granules to mix in water and drink
  • suppositories (solid, bullet-shaped products to put inside your back passage)
  • enemas (liquid injected through a thin tube into your back passage)

Your pharmacist or doctor will usually recommend trying a bulk-forming laxative first, if changing your diet and lifestyle hasn’t eased your constipation. Bulk-forming laxatives usually come as powders or granules. It's important to drink lots of water when you take them to stop your bowel getting blocked. Bulk-forming laxatives usually start working in 24 hours, but may take two to three days to work fully.

If your poo is still hard, your pharmacist or doctor may recommend you try an osmotic laxative. You’ll need to drink plenty of fluids while taking osmotic laxatives to make sure you don’t get dehydrated. Osmotic laxatives may take one to two days to start working.

If your poo is soft but you’re still finding it hard to poo, your pharmacist or doctor may recommend a stimulant laxative. If you’re taking tablets, capsules or liquids, your doctor or pharmacist may suggest you take these at night. The tablets, capsules and liquids start to work in six to 12 hours so you’ll be able to poo by the next morning. The suppositories work much more quickly – within 20 to 60 minutes.

Lubricant laxatives and stool softeners don’t always work well on their own. Your doctor may prescribe these with another laxative.

Make sure you read the label and product information leaflet to check how to use your particular laxatives – different types and products vary.

How long should I take laxatives for?

You should take laxatives for the shortest amount of time possible to ease your constipation. Taking some types of laxatives, especially stimulant laxatives, for a long time can be harmful.

You’ll usually be advised to stop taking laxatives once your poos are soft and easy to pass again. But sometimes you may need to take laxatives for a few weeks or even months, especially if you have chronic constipation (constipation that lasts for a long time). If your constipation is caused by certain medicines, you may need to take laxatives until you no longer need these medicines.

Always read the patient information leaflet that comes with your medicine. If you have any questions, ask your pharmacist or doctor for advice.

Interactions of laxatives

Some laxatives can stop your digestive system from absorbing certain nutrients and some other medicines you’re taking.

You shouldn’t take ispaghula husk if you’re taking medicines that can make you constipated.

You shouldn’t take indigestion remedies two hours before or after you take bisacodyl tablets.

Check with your GP or pharmacist before you take any other medicines, vitamin supplements or herbal remedies at the same time as a laxative.

Side-effects of laxatives

Laxatives can cause some side-effects. Side-effects are the unwanted effects that you may get from taking a medicine. We haven’t listed them all here, so it’s important to check the information leaflet that comes with your medicine. Below are some of the most common ones.

  • Bulk-forming laxatives can make you bloated and cause wind, stomach pains and cramps. Very occasionally, having too much bulk laxative or not drinking enough fluid while you take it can block your bowel.
  • Osmotic laxatives can cause bloating, wind, nausea (feeling sick) and stomach cramps. They can also cause you to become dehydrated, so it's important that you drink enough fluids to stop this from happening.
  • Stimulant laxatives can cause stomach pains and cramping. They may give you diarrhoea if you use them too regularly.

You can usually avoid or ease most laxative side-effects if you start with a lower dose of tablets, syrups or capsules and increase this slowly. When you stop using laxatives, it’s important to come off them slowly too. This means lowering the dose over two to four weeks until you’re pooing regularly (at least three times a week) and your poos are soft without a laxative.

Frequently asked questions

  • Laxatives can’t help you lose weight. In fact, taking laxatives if you don’t need them or taking them regularly can be harmful. The best way to lose weight is by eating a healthy diet and exercising regularly.

    Laxatives help you poo more easily. But they won’t stop you absorbing calories. Laxatives work on your lower bowel after most of the calories in your food have already been absorbed.

    Taking laxatives occasionally for constipation shouldn’t do you any harm. But taking them regularly may make you dehydrated if you don’t drink the recommended amount of fluids. Dehydration can make you feel weak and faint and cause headaches. If you take too many laxatives, this may cause diarrhoea or block your bowel. Taking laxatives regularly may also affect the electrolyte and mineral balance in your body. This can cause muscle aches and pains and a lack of energy.

  • If you’re not pooing very often or you’re having to strain to poo, you may be constipated. It may help if you eat more fibre and drink more fluid. Try eating more fruit and vegetables and cereals containing bran. Aim for around 30g of natural fibre a day. It may take up to four weeks for you to poo more easily. Too much fibre can cause wind and bloating, so you’ll need to get the balance right and see what works for you. Exercising regularly may also help to ease your symptoms.

    If changing your lifestyle doesn’t work, you could try laxatives. But speak to your doctor or pharmacist. They may recommend you try a bulk-forming laxative first. This will help to increase the amount of fibre in your diet.

    Several other types of laxative are available over the counter from pharmacies and on prescription. Some may work better for you than others, depending on your symptoms and circumstances. Ask your pharmacist or GP for advice.

  • Foods that are high in fibre can act as natural laxatives by making your poo softer and easier to pass. A food is high in fibre if it contains at least 6g of fibre in every 100g. In the UK, adults are recommended to eat 30g of fibre every day. Foods that are high in sorbitol may also help to prevent and treat constipation.

    Natural laxatives include many fruits, vegetables, beans, pulses, nuts and seeds. Fruits that can act as laxatives include apricots, grapes, plums and prunes. You could combine these with wholegrain or wholemeal products, such as breads, cereals, pasta and rice. Research has found that prunes work just as well as bulk-forming laxatives containing ispaghula husk in treating constipation.

    If you add more fibre into your diet, you’ll need to drink more fluids too, as this will help the fibre to work properly. Aim for eight to ten cups of fluid each day. If you don’t drink enough fluids, you could become dehydrated.

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  • Reviewed by Laura Blanks, Specialist Health Editor, Bupa Health Content Team, August 2019
    Expert reviewer, Shabina Azmi, Pharmacist
    Next review due August 2022