Hertfordshire Community Eating Disorders Service
(CEDS)
The effects of laxative abuse on physical health
Laxatives are medications used on a short-term basis to relieve constipation.
There are several different types, which have different roles depending on the
cause of the constipation. Some are available over the counter from chemists,
whilst others are available on prescription. Many such laxatives are described
as “natural” or “herbal”, which suggests they are safe, and carry no risk.
However, this is not the case. The most common type of laxative abused in
eating disorders is stimulant laxatives, such as Senokot or Ducolax.
(NB.Laxatives prescribed under medical supervision are fine, especially since
the doctor will prescribe a different type of laxative- usually one that is bulkforming, such as Fybogel or Lactulose.) You may have started taking laxatives
because of a belief that they will help you lose weight, or to compensate for
eating more food than you feel comfortable with. Abuse of stimulant laxatives
will leave you feeling empty, with a much desired flat stomach, and convinced
that you have not gained weight. However, any weight loss and change in
body shape is the result of the dehydrating effect of watery diarrhea and the
complete emptying of the large bowel. It has nothing to do with changes in fat,
muscle or carbohydrate levels in the body. This is because laxatives work on
the large intestine, whereas food is digested and absorbed in the small
intestine.
Laxative abuse can have serious side effects on health, many related to low
potassium levels, (hypokalemia) secondary water diarrhea. This can be
serious enough to trigger dangerous cardiac problems and other medical
problems, whilst the long-term dehydration related to laxative abuse can lead
to kidney failure or problems with kidney function. Other problems that can
occur include rectal bleeding (probably related to chemical irritation from the
laxatives), urinary tract infections, muscle weakness, confusion or
convulsions. Laxatives may also cause you problems when you try to stop
taking them. The large bowel gets tolerant to the level of laxatives taken, so
you may have found you needed to take more and more to get the same
effect. Stopping them suddenly is then likely to cause water retention due to
the fact the watery diarrhea has a dehydrating effect. It is possible for weight
to increase up to 5kg’s or more when laxatives are stopped abruptly, due to
the fluid levels returning to normal. The rise in weight is detectable both from
weighing scales(which can reinforce the belief that laxatives lead to weight
control), and from seeing differences in your body, such as feeling more
bloated, plus possible swelling of the feet and ankles.
The swelling is called rebound edema and usually lasts for 10-14 days after
stopping laxative abuse, following which weight drops slightly due to
normalization of body water levels.
You may also experience constipation when you stop taking laxatives.
However, there are healthy ways to help your body return to normal bowel
function, such as making sure you eat a range of foods that contain dietry
fibre (wholemeal or granary bread, high fibre breakfast cereals, brown rice,
lentils and beans (e.g., kidney beans), and fruit and vegetables, drinking
enough fluids (around 0.5 – 2 litres a day) and developing a routine for going
to the toilet (even if you don’t find it easy to pass a bowel motion to start with).
Giving up laxatives can be really anxiety provoking so talk to your
clinician/doctor/dietitian if you feel you need more support.
Reference: “Cognitive Behavioural therapy for eating disorders: a comprehensive treatment guide” (2007) Waller et
al.Page 403/404 Appendix 2B