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Laxatives

Key points

  • Laxatives are foods or medicines that encourage bowel movement.
  • Laxatives can be used to treat constipation or clear the bowels before a medical procedure.
  • Laxatives can have side-effects, including wind and stomach pains.

Laxatives are foods or medicines that encourage bowel movement. Laxatives can be used to treat constipation or clear your bowels before a medical procedure.

Why would I take laxatives?

Your GP or pharmacist may advise you to take laxatives if you have constipation. Constipation is when you have trouble opening your bowels. It’s a common problem, but can mean different things to different people, because bowel habits differ from person to person. However, health professionals define constipation in the following ways.

  • You open your bowels less than three times a week.
  • You need to strain to open your bowels on more than one in four occasions.
  • You pass hard or pellet-like stools on more than one in four occasions.

You may also be advised to take laxatives if you have a condition that could get worse if you strain during bowel movements, for example:

Laxatives are also prescribed to clear your bowels before surgery. Or if you’re having a test to look inside your large bowel, such as a barium enema or colonoscopy.

What are the main types of laxative?

There are several types of laxative – some of which you can buy without a prescription. The main types are:

  • bulk-forming laxatives (also known as fibre supplements), such as wheat or oat bran, ispaghula husk, methylcellulose and sterculia
  • osmotic laxatives, such as lactulose, macrogols, sodium citrate enema and phosphate enema
  • stimulant laxatives, such as senna, and glycerol or bisacodyl suppositories
  • faecal softener laxatives, such as arachis oil and docusate sodium

How do laxatives work?

Each type of laxative works in a different way to help relieve or prevent constipation.

  • Bulk-forming laxatives work by increasing the amount of fibre you have in your diet so you produce more faeces. This then encourages your bowels to move and push the faeces out.
  • Osmotic laxatives work by increasing the amount of water that stays in your faeces, which makes them easier to pass.
  • Stimulant laxatives work by stimulating nerves in your bowel so that your intestine moves and pushes the faeces out.
  • Faecal softener laxatives work by lubricating and softening your faeces, which makes them easier to pass.

How to take laxatives

Laxatives are available as:

  • tablets, syrups or capsules you swallow
  • powders or granules that you mix in water
  • suppositories (capsules you put inside your back passage)

Sometimes, a laxative is given as an enema (liquid injected through a thin tube into your back passage). Enemas and suppositories work within minutes to clear your bowel.

Choosing the right type of laxative

Bulk-forming laxatives

Bulk-forming laxatives are usually recommended as the first type to try, especially if you find it difficult to get more natural fibre in your diet. Your doctor may also prescribe a bulk-forming laxative if you have a colostomy or ileostomy bag, irritable bowel syndrome, piles (haemorrhoids) or an anal fissure.

Bulk-forming laxatives usually come as powders or granules that you mix in water. It's important to drink enough fluids so that the extra bulk doesn’t build up in your bowel and cause a blockage. Bulk-forming laxatives may take two to three days to start working.

Osmotic laxatives

If a bulk-forming laxative doesn’t work or isn’t tolerated you may need an osmotic laxative. This too may take two to three days to start working. You must drink enough fluids while taking osmotic laxatives to avoid getting dehydrated.

Stimulant laxatives

Stimulant laxatives should only be used if other types of laxatives haven’t worked. They come as tablets, liquids, suppositories and enemas. Tablets and liquids work within six to 12 hours, so you should take them at night for an effect the next morning.

Faecal softener laxatives

Faecal softeners come as medicines taken by mouth, as well as suppositories or enemas. The enemas usually work faster.

Laxative treatment

Laxatives are usually only recommended for short-term use if changes to your diet, such as increasing your fibre and fluid intake, haven't worked. Taking laxatives over a long time can be harmful. It’s generally recommended that you stop taking laxatives once your bowel movements have returned to normal.

Sometimes you may need to take laxatives for weeks or months, especially if you have chronic constipation. However, you shouldn’t take laxatives for longer than a week unless your doctor advises you to. Also, you shouldn't give laxatives to children unless your doctor has prescribed them.

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

Special care

Check with your GP or pharmacist before taking a laxative if:

  • you’re pregnant or breastfeeding
  • you know that your kidneys or liver aren't working properly
  • you have an inflammatory bowel disease such as ulcerative colitis

Side-effects of laxatives

This section doesn't include every possible side-effect of laxatives. Please read the patient information leaflet that comes with your medicine for more information. However, some common side-effects are listed below.

  • Bulk-forming laxatives can cause bloating, wind, stomach pains and cramps. Rarely, they can block your bowel.
  • Osmotic laxatives can cause bloating, wind, nausea and stomach cramps. You may also become dehydrated and get a headache.
  • Stimulant laxatives can cause stomach pains and cramping, and diarrhoea.
  • Suppositories and enemas can cause abdominal pain and irritate the skin around your anus.

Interactions of laxatives with other medicines

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

Names of common laxatives

The main types of laxatives are shown in the table below.

All medicines have a generic name. Many medicines also have one or more brand names. Generic names are usually written in lower case, whereas brand names start with a capital letter.

There are many different products marketed for constipation. Some have more than one ingredient, or different ingredients sold under the same brand name. Ask your pharmacist for advice.

 

Generic names Examples of common brand names
Bulk-forming laxatives  
bran  
ispaghula husk Fibrelief, Fybogel, Isogel, Ispagel Orange, Regulan
methylcellulose Celevac
sterculia Normacol, Normacol Plus
Osmotic laxatives  
lactulose Duphalac, Lactugal, Laevolac
macrogols Movicol, Movical-Half, Movicol-Paediatric
magnesium salts Phillips Milk of Magnesia, Epsom Salts, Original Andrews Salts
phosphates Fleet enema, Fletchers' Phosphate Enema
sodium citrate Microlette, Micralax, Relaxit
Stimulant laxatives  
bisacodyl Dulcolax
co-danthramer Codalax
co-danthrusate (with docusate sodium) Normax
docusate sodium Dioctyl, Docusol, Norgalax Micro-enema (enema)
glycerol Glycerin suppositories
senna Manevac, Senokot
sodium picosulfate Dulcolax Pico Liquid, Dulcolax Pico Perles
Faecal softener laxatives  
arachis oil Arachis oil enema
liquid paraffin Liquid paraffin oral emulsion

 

Reviewed by Alice Rossiter, Bupa Health Information Team, February 2014.

For answers to frequently asked questions on this topic, see FAQs .

For sources and links to further information, see Resources .

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  • This information was published by Bupa's Health Information Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals. Photos are only for illustrative purposes and do not reflect every presentation of a condition. The content is intended only for general information and does not replace the need for personal advice from a qualified health professional. For more details on how we produce our content and its sources, visit the about our health information page.

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