When you’re constipated you might decide to reach for the nearest laxative (at least a third of people do), or you might try the well-renowned prunes and rhubarb, or herbs like parsley and mint. Foods with laxative properties can affect people in different ways, and some might not work at all.
What are Laxatives?
Medicinal laxatives generally fall into four main types:
- Stimulant laxatives
- Bulk-forming laxatives
- Stool softeners
- Osmotic laxatives
Stimulant laxatives can be in tablet or liquid form and are designed to help the muscles move waste matter through the bowel more quickly. Suppositories and enemas are normally also included in this category.
Bulk-forming laxatives or fibre supplements in the form of powders or tablets work in the same way as dietary fibre, providing extra bulk to the stools which encourages their movement through the digestive system. An example of a bulk-forming agent is psyllium husk. Bulk-forming agents should always be taken with plenty of water.
Stool softeners may be capsules or enemas, and might take three or four days to work. Stool softeners encourage additional fluids and fats to be absorbed into the stool in the colon, making for easier passage through the system.
A similar effect is produced by osmotic laxatives, which increase the amount of water in the bowel to help the smooth passage of stools. It’s difficult to say if one works better than the others because there haven’t been many clinical trials to compare them, but generally they offer temporary relief.
Side effects of Laxatives
Generally speaking, laxatives should be taken only for a couple of weeks, as overuse could cause diarrhoea or irritate the intestines. More of concern is the theory that the bowel might get used to being constantly helped, in which case it will not work as efficiently as it should when you stop taking the medicine. Laxatives can also have side effects such as wind, bloating, and abdominal discomfort.  Make sure that the laxative you choose will not interfere with any other medications or herbal remedies that you are already taking.
Alternatives to Laxatives
Doctors and dieticians usually advise a change of diet to prevent further problems with constipation. Where possible, treating yourself through changes to your diet is always a positive first step. Nutritionist & doctors recommend increasing your intake of dietary fibre or ‘roughage’ found in fruit, vegetables, and bran cereals, and also to make sure your water intake is at least 1.5 litres a day, or 2 litres if eating a high-fibre diet.
After making changes to your diet, another option to provide relief from constipation could be looking at natural remedies, such as herbal remedies or probiotics. These could have the benefits of working without the side effects of medicines. Often natural remedies will come with fewer contraindications, for example pregnant women might be able to find natural remedies which can be safely taken. Read Megan's article on natural remedies for constipation.
References & Footnotes
 The BI Omnibus Study: An international survey of community prevalence of constipation and laxative use in adults. Digestive Disorders. 2006: 20-25 May
 Boehringer Ingelheim Pharmaceuticals (2007) Dulcolax vs Placebo in Functional Constipation