Treatment with a laxative is needed only if self care measures, such as eating plenty of fibre and drinking enough fluid, do not work well in relieving constipation.
What are the different types of laxatives?
There are several types of laxatives that differ in how quickly they start working, how helpful they are in different situations, possible side effects, their taste and their cost.
The four main groups of laxatives are:
- fibre supplements (bulk-forming laxatives)
- laxatives that draw water into the bowel (osmotic laxatives)
- stimulant laxatives that act on the bowel's nervous system to get the bowel moving
- faecal (poo) softeners
More-detailed information about these four types of laxatives, including common brand names, is provided in the table at the bottom of this page.
How are laxatives taken?
There are different forms of laxatives. Some can be taken by mouth; others as an enema inserted in the bottom:
- Tablets, capsules and powders are taken by mouth (called oral formulations), and depending on the type of laxative, can take hours or days to work.
- Rectal formulations (enemas or suppositories) are inserted into the rectum (bottom). These are usually effective within minutes to an hour, and are mainly used as a last resort to treat severe constipation.
Which laxative should I use?
Always seek guidance from your doctor or pharmacist as to which laxative is best for you.
Usually, treatment with a bulk-forming laxative is tried first. If faeces (poos) remain hard despite using a bulk-forming laxative then an osmotic laxative tends to be tried, or used in addition to a bulk-forming laxative.
If bowel movements are soft but you still find them difficult to pass then a stimulant laxative may be added in. In cases of severe constipation (impaction), high doses of the osmotic laxatives may be used.
How to use laxatives safely
- Drink plenty of water:
- When taking laxatives, you should try to drink at least 8 to 10 cups of water a day.
- This is because laxatives, especially an osmotic laxative, can make you dehydrated.
- If you take a bulk-forming laxative and you do not drink enough fluid this can cause a blockage in the gut as the faeces (poos) may become dry and difficult to pass.
- Use only for short periods of time:
- Long-term use can make your body dependent on them, so your bowel no longer functions normally without them.
- Generally, it is recommended that you do not take laxatives for more than 5 to 7 days in a row.
- If symptoms persist after this time contact your doctor for advice.
Possible side effects
- stomach pain or cramps
- bloating, gas in the tummy
- flatulence or 'farting'.
|Bulking agents (fibre supplements)||Examples|
|Faecal or stool softeners||Examples|
New Zealand Formulary Patient Information
Laxatives New Zealand Formulary