HealthInfo Waitaha Canterbury
Medicines for constipation (adults)
Rongoā mō te kōroke (pakeke)
Laxatives are medicines that help you poo (pass a bowel motion). Different laxatives take different amounts of time to work. Some work very quickly while others take a few days.
Ideally, you should only use them for a short time. Changing what you eat and drink and becoming more active are the best longer-term treatments for constipation.
There are several groups of laxatives.
Bulk-forming laxatives
Bulk-forming laxatives are also called bulking agents or fibre supplements. This type of laxative is usually the first one that people try.
Bulk-forming laxatives work by making your poo softer, which makes it easier to pass. You can get them from your general practice team on prescription, or you can buy them over the counter at a pharmacy. You can also get some at the supermarket. Examples of bulk-forming laxatives include psyllium (Konsyl-D, Metamucil, Mucilax) and wheat dextrin (Benefiber).
Using bulk-forming laxatives
These can have some effect within 12 to 24 hours, but it may take 2 to 3 days for bulk-forming laxatives to have their full effect.
It is important to drink plenty of fluid (at least 8 cups a day) if you are taking a bulk-forming laxative. This helps to stop it blocking your digestive system.
While these laxatives help with constipation, some may cause bloating in your abdomen (tummy) or excess wind (farting). You can usually avoid this by starting on a small dose and gradually increasing it. Take them according to the manufacturer's directions or as your general practice team, pharmacist or dietitian tells you.
Stimulant laxatives
These stimulate the nerves in your bowel, so it squeezes harder and pushes the poo (faeces) out. They are available as tablets or capsules that you swallow, or a suppository (a medicine that you put into your bottom).
The tablets or capsule usually take 6 to 12 hours to work but the suppository can work within 15 to 60 minutes.
Senna and bisacodyl are stimulant laxatives.
Osmotic laxatives
These work by drawing water from the rest of your body into your bowel to soften poo and make it easier to pass. Sometimes doctors prescribe an osmotic laxative for someone with faecal impaction.
Osmotic laxatives are available as a syrup or powder that you mix with water and drink. They are also available as a liquid or gel enema that you put into your bottom. The syrup and powders take 1 to 3 days to cause a bowel motion, but enemas usually work within 30 minutes. Lactulose and macrogol are osmotic laxatives.
Faecal (stool) softener laxatives
These soften your poo. They are available as drops or tablets that you swallow, or a liquid or gel enema that you put into your bottom. The drops or tablets can cause a bowel motion within 12 to 72 hours. Enemas usually cause a bowel motion within 30 minutes. Docusate is a faecal softener laxative.
Important
The fact that you can buy some laxatives over the counter does not mean they are safe for all people. If you have any bowel condition, are pregnant or breastfeeding or have diabetes, liver or kidney problems, it is important that you talk to your general practice team or pharmacist before using any laxatives.
HealthInfo recommends the following pages
- Patient.info – Laxatives
More information on the different types of laxatives, how they work, how to use them and their side effects.
Written by HealthInfo clinical advisers. Last reviewed August 2024.
SourcesReview key: HICSA-13804
