Dr Margaret answers emailers’ embarrassing problems
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Laxatives

Dear Dr Margaret
I have been using a laxative for years, and it keeps me regular. Could this be harmful in any way?

There are various types of laxative. Long-term use of so-called ‘bulk laxatives’ does not cause problems. Most concern has been about the ‘stimulant’ type. Our section on constipation explains these different types.

Since the 1920s, doctors have suspected that using stimulant laxatives regularly for years (especially in increasing doses) might make the colon (lower bowel) lazy. Then, if you stopped using the laxative, your constipation would be worse than before. They called this condition ‘cathartic colon’. Doctors are now very doubtful about the idea of cathartic colon, because there is no good evidence that it occurs. People who were diagnosed as having cathartic colon probably had some other reason for their persistent constipation, and laxatives were wrongly blamed.

Another worry has been that stimulant laxatives might make colon cancer more likely. However, a German study, involving more than 550 patients, has shown that using laxatives does not lead to colon cancer. Some of the patients in this study had been using laxatives for more than 20 years.

Other types of laxatives can sometimes cause problems, especially if they are overused. For example, the so-called ‘osmotic laxatives’ can upset the balance of salts and water in the body, especially in a frail or elderly person. There have been reports that the long-term use of laxatives containing oils (such as liquid paraffin) can interfere with the body’s ability to absorb some vitamins from food. Oil-based laxatives can seep out of the anus, causing anal itching.

So it seems that using a laxative for years is unlikely to cause any serious problems, as long as you keep the dose low. Look at our section on adult constipation for more information about laxatives and constipation in general.

Sources of information
Eltringham M, Yiannakou Y. Constipation: current approaches to treatment. Prescriber 2003;19 April:69–80.

Kamm MA. Constipation and its management. British Medical Journal 2003;327:459–60.

Lembo A, Camilleri M. Chronic constipation. New England Journal of Medicine 2003;349:1360–8.

Nusko G, Schneider B, Schneider I et al. Anthranoid laxative use is not a risk factor for colorectal neoplasia: results of a prospective case control study. Gut 2000;46:651–5.

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