The Aword

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How do we define diarrhoea? The term comes from the Greek dia
(through) and rhein (to flow).

Essentially diarrhoea is three or more liquid or semi-liquid bowel movements
in a day.

Acute diarrhoea would be an episode of 1-5 days. When it persists for more
than 3 weeks, it is termed chronic diarrhoea.

Diarrhoea arises because of failure of the large intestine to absorb water
from faeces. This may result from a number of causes that result in
intestinal hurry (the faeces passing through the colon too rapidly to allow
the fluid to be absorbed.)

As mentioned above, IBD and one type of IBS can cause diarrhoea (a
second type of IBS causes fluctuating constipation and diarrhoea).

Malabsorption syndromes such as coeliac disease may cause diarrhoea.

Infective causes of diarrhoea are not within the remit of this article. These
include food poisoning, viral or bacterial gastroenteritis and parasites
(tapeworm etc.)

Food allergies can also result in diarrhoea.

Medication-induced diarrhoea: there are a number of drugs that can cause
diarrhoea as a side effect. (Check the Patient Information Leaflet for each
medication you take). Antibiotics and antacids are particularly common

Lack of vitamin B3 or folate or excess vitamin D or C can cause diarrhoea.
Neurogenic diarrhoea may occur in conditions such as diabetes. This involves autonomic neuropathy affecting either the small or large intestine (or both)
and may cause either constipation or diarrhoea.

There may also be decreased absorption of fat from the diet, which leads to steatorrhea: pale, waxy loose stools. Faecal incontinence may also occur, especially at night (see below).

Anxiety can also cause acute diarrhoea.

Diarrhoea may signal the onset of more serious conditions such as
appendicitis. (See below)


Acute attacks:

The primary concern is to maintain hydration, as loss of water in the stool
(especially if there is also vomiting) can quickly dehydrate the patient.
Loss of salts (electrolytes) also occurs, and may result in low sodium and

It is vital to drink plenty of fluids. In severe cases, a preparation called
Dioralyte is available from chemists: this replaces lost salts as well as water.

Alternatively, Coca-Cola allowed to go flat will provide the same sort of
replacement (not the Diet type though) of sugar and salts.

There may be abdominal cramps, which can be relieved by paracetamol or
perhaps antispasmodic medication such as Buscopan.

Antimotility drugs may have a role in some cases of acute diarrhoea (but
not in children): Diarrest (codeine) Imodium (Loperamide) and Lomotil (co-phenotrope) are the commonest.

Regime of acute diarrhoea:

  • Rest
  • Plenty of fluids: water/dioralyte/flat coke
  • Avoid all food for 12-24 hours
  • Introduce foods slowly, using easily digested, bland foods to begin with (plain yogurt, toast, plain biscuits)
  • Paracetamol for cramps


If any of the following occur, immediate medical attention should be sought.

  • Blood in the stools
  • Persistent fever for more than 48 hours
  • Inability to drink fluids (due to vomiting)
  • Severe abdominal pain: especially if constant rather than in colicky bouts
  • Diarrhoea after a trip to a foreign country
  • Diarrhoea in an infant under 1 year old.
  • Persistent diarrhoea for more than 3 days.

Chronic diarrhoeas due to IBS or IBD have been discussed above.

Malabsorption syndromes such as coeliac disease require specific
management, e.g. a gluten-free diet.

A Johns Hopkins study in USA has found that zinc supplements have been
found to help children suffering from acute and persistent diarrhoea:
significantly reducing the duration of symptoms. The study is reported in
December 2000 issue of the American Journal of Clinical Nutrition. Further
work is needed on this.