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
- adding bulking agents, such as wheat bran, to your diet
- drinking plenty of fluids
- exercising regularly
Some laxatives are available at supermarkets and pharmacies without a prescription. Other laxatives are also available on prescription from your GP.
Types of laxatives
There are 4 main types of laxatives. Contact 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).
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 (also called by the brand names Movicol, Laxido, Molaxole and Macrolief)
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
Poo-softener laxatives increases the water in your poo and make it easier to pass.
They include:
- arachis oil
- docusate sodium
Check if you can take laxatives
Laxatives are not suitable for everyone.
Do not use laxatives if you have:
- a perforated bowel
- phenylketonuria
- a blockage in your digestive system
Check with your GP or pharmacist before taking laxatives if you:
- have any allergies
- have ulcerative colitis, irritable bowel syndrome (IBS) or Crohn's disease
- have a colostomy or ileostomy
- have 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 and laxatives
Always check with your GP or pharmacist before giving your baby or child a laxative.
Laxatives are not generally recommended for babies who have not been weaned.
If your baby is not weaned but 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
- increase the amount of fibre in their diet
If they're still constipated, your GP or pharmacist may then recommend a laxative.
Constipation in children and babies
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 or drink
- a capsule you place inside your bottom where it dissolves (suppositories)
- liquids or gels you place directly into your bottom (enema)
Some laxatives have to be taken at certain times of the day, such as first thing in the morning or last thing at night.
You may be prescribed a laxative to use regularly. But your GP should always supervise this.
Never take laxatives for longer than the recommended time.
Never take more than the recommended dose of laxatives. This can be harmful and cause side effects.
If you're taking bulk-forming or osmotic laxatives, drink plenty of fluids. These laxatives can cause dehydration.
Non-urgent advice: Contact your GP if:
- your constipation has not improved after taking laxatives for a week
Side effects of laxatives
Laxatives can cause side effects. They're usually mild and should pass once you stop taking the laxative.
Contact your GP or pharmacist if side effects bother you or do not go away. Get emergency help if you have signs of a serious allergic reaction.
Side effects can include:
Bloating and farting
Take laxatives between meals instead of before or after them. Try to avoid any foods that may make your symptoms worse like lentils, peas, beans and onions. It might also help to:
- eat smaller and more frequent meals
- eat and drink slowly
- exercise regularly
Some pharmacy remedies help wind. Ask your pharmacist for advice.
Tummy cramps
Try to rest and relax. It can help to eat and drink slowly and have smaller and more frequent meals. Putting a heat pad or covered hot water bottle on your stomach may also help.
If these symptoms carry on, or if you're in a lot of pain, contact your pharmacist or GP.
Feeling sick (nausea)
Try taking the laxative with meals or mixing your dose with some water or fruit juice. Drink lots of fluids, such as water or squash. If you're being sick, take small, frequent sips to avoid dehydration.
Do not take any other medicines to treat vomiting without speaking to a pharmacist or GP.
If you take contraceptive pills and you're being sick, your contraception may not protect you from pregnancy. Check the pill packet for advice.
Dehydration
Dehydration can make you feel lightheaded, have headaches and have pee that's a darker colour than normal. Drink plenty of water or squash.
Speak to a pharmacist if you have signs of dehydration.
Using laxatives too often can cause:
- diarrhoea
- your bowel to become blocked
- unbalanced salts and minerals in your body
Laxatives do not help with weight loss.
Serious allergic reaction
You might need emergency help if you have a serious allergic reaction to laxatives.
Emergency action required: Contact 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).
See the patient information leaflet that comes with your medicine for a full list of side effects.
Taking laxatives 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 you plan to take stimulant laxatives
- epilepsy medicines, such as levetiracetam or phenytoin
Some laxatives may delay or reduce how your body absorbs other medicines.
For most people, 1 laxative will be enough to relieve constipation.
But you may need to take 2 different types of laxatives at the same time. This is to get your bowels moving again.
Only take 2 laxatives together if your GP or pharmacist recommends it. You are more likely to get side effects.
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).
