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Laxatives

Laxatives are a type of medicine that treats constipation.

They're often used if lifestyle changes have not helped, such as:

  • increasing fibre in your diet
  • drinking plenty of fluids
  • taking regular exercise

Laxatives are available at pharmacies and supermarkets. They're also available on prescription from a your GP.

Get emergency help

Emergency action required: Phone your GP immediately and stop taking laxatives if you have:

  • difficulty breathing
  • swelling of the face, lips, tongue or throat

These are signs of a serious allergic reaction (anaphylaxis).

Types of laxatives

There are 4 main types of laxatives. Speak to your GP or pharmacist if you're unsure which one to use.

Bulk-forming laxatives

Bulk-forming laxatives increase the "bulk" or weight of poo which stimulates your bowel.

They take 2 or 3 days to work.

Bulk-forming laxatives include:

  • Fybogel (also known as ispaghula husk)
  • methylcellulose

Osmotic laxatives

Osmotic laxatives draw water from the body into your bowel to soften poo and make it easier to pass.

They take 2 or 3 days to work.

They include:

  • lactulose (also known as Duphalac or Laxose)
  • macrogol

Stimulant laxatives

These stimulate the muscles that line your gut helping to move poo along to your bottom.

They take 6 to 12 hours to work.

They include:

  • bisacodyl (also called by the brand name Dulcolax)
  • senna (also called by the brand name Senokot)
  • sodium picosulfate

Poo-softener laxatives

This type of laxative works by letting water into poo to soften it and make it easier to pass.

They include:

  • arachis oil
  • docusate sodium

Check if you can take laxatives

Laxatives are not suitable for everyone.

Emergency action required: Do not use laxatives if you have:

  • a perforated bowel
  • an allergy
  • phenylketonuria
  • an obstruction in your digestive system

Check with your GP or pharmacist before taking laxatives if you:

  • have irritable bowel syndrome (IBS), Crohn's disease or ulcerative colitis
  • have a colostomy or ileostomy
  • a history of liver or kidney disease
  • are pregnant, trying for a baby, or breastfeeding
  • have diabetes (some laxatives can increase blood sugar)
  • have difficulty swallowing
  • are lactose intolerant (some laxatives contain lactose)

Before using a laxative read the information leaflet to make sure it's safe for you to take.

Children

Always check with your GP or pharmacist before giving your baby or child a laxative.

Laxatives are not recommended for babies who have not been weaned.

If your unweaned baby is constipated, try giving extra water in between feeds. Gently massaging their tummy and moving their legs in a cycling motion may also help.

Children who eat solid foods may be able to use laxatives, but first make sure they drink plenty of water or diluted fruit juice, and increase the amount of fibre in their diet.

If they're still constipated, your GP or pharmacist may recommend a laxative.

How and when to take laxatives

How you take a laxative depends on the form it comes in. Ask a pharmacist if you're not sure how to take your laxative.

They're commonly available as:

  • tablets or capsules you swallow
  • sachets of powder you mix with water and drink
  • a capsule you place inside your bottom where it dissolves (suppositories)
  • liquids or gels you place directly into your bottom

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

If you're taking bulk-forming or osmotic laxatives, drink plenty of fluids. These laxatives can cause dehydration.

Some laxatives can be taken long-term while some are only suitable for short-term use. Never take laxatives for longer than the recommended time.

Never take more than the recommended dose of laxatives as this can be harmful and cause side effects.

If your constipation has not improved after taking laxatives for a week, speak to your GP.

Side effects of laxatives

Laxatives can cause side effects. They're usually mild and should pass once you stop taking the laxative.

Talk to your GP or pharmacist if side effects bother you or don't go away. Get emergency help if you have signs of a serious allergic reaction.

Side effects can include:

  • bloating
  • farting
  • tummy cramps
  • feeling sick
  • dehydration
  • feeling lightheaded
  • headaches
  • pee that's darker than normal

Using laxatives too often can cause diarrhoea, the bowel becoming blocked and unbalanced salts and minerals in your body.

Laxatives do not help with weight loss.

See the patient information leaflet that comes with your medicine for a full list of side effects.

Non-urgent advice: Find your patient information leaflet

Your patient information leaflet is the leaflet that comes with your medicine. You can find a digital version of the leaflet online.

Report side effects

You can report any suspected side effects to the the Health Products Regulatory Authority (HPRA): report an issue - hrpa.ie

Interactions with other medicines

Check with your GP or pharmacist before using laxatives if you are taking:

  • medicines that cause constipation, such as codeine or morphine
  • medicines for a heart condition or heart rhythm problem and plan to take stimulant laxatives

Some laxatives may delay or reduce how your body absorbs other medicines. 

Fact check

This content was fact checked by a pharmacist, a GP, the National Medication Safety Programme (Safermeds) and the Health Products Regulatory Authority (HPRA).

Page last reviewed: 24 September 2021
Next review due: 24 September 2024

This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 123.