Diarrhoea: causes and symptoms
Diarrhoea is when your bowel movements become loose or watery. The definition of diarrhoea is passing loose or watery bowel movements 3 or more times in a day (or more frequently than usual).
Diarrhoea occurs when the lining of the intestine is unable to absorb fluid, or it actively secretes fluid.
In addition to frequent, watery bowel movements, the stool may also contain mucus, pus, blood or excessive amounts of fat.
Diarrhoea can be accompanied by:
- painful abdominal cramps;
- bloating; and
- generalised weakness.
Diarrhoea can cause dehydration, especially in young children and older people. Symptoms of dehydration in adults can include:
- lack of energy;
- passing less urine than normal;
- dizziness or light-headedness; and
- the skin on the back of your hand being slow to return to position after being pinched upwards.
Symptoms of mild to moderate dehydration in children can include:
- dry mouth;
- passing less urine than usual (often noticed as fewer wet nappies in babies and toddlers);
- listlessness; and
- less tears when crying.
Signs of severe dehydration in children include:
- sunken eyes, cheeks or belly, or a sunken fontanelle (the soft spot on the top of the head in babies and toddlers).
People with diarrhoea, especially the very young and the very elderly, are at risk of becoming rapidly dehydrated. This requires immediate medical attention.
Diarrhoea may have many different causes including:
- infection (with a virus, bacteria or parasite);
- a change in diet;
- food intolerance (e.g. lactose);
- drinking excess alcohol;
- inflammatory bowel disease (ulcerative colitis or Crohn’s disease);
- coeliac disease;
- malabsorption (e.g. due to problems with the pancreas);
- surgery (e.g. when part of the bowel has been removed);
- irritable bowel disease; or
- medicines (e.g. a side effect of antibiotics or some diabetes medications).
Infectious diarrhoea is most commonly caused by viruses passed from person to person, or by eating or drinking food or water contaminated with viruses or bacteria.
Diarrhoea in very young children is often caused by viral infections. Rotavirus infections were a common cause, but this risk is reduced by the rotavirus vaccine, which can prevent gastroenteritis (or reduce the risk of severe gastroenteritis) caused by rotavirus infection. The vaccine is given as 2 or 3 doses as part of the routine childhood immunisation schedule at 2 months, 4 months and sometimes also at 6 months. Many other viruses still commonly cause diarrhoea in infants and toddlers.
What can you do to help?
If you have diarrhoea you should drink plenty of fluids. Suitable fluids include:
- oral rehydration fluids (available from pharmacies);
- diluted cordial concentrate (one part cordial concentrate to 20 parts water); and
- diluted soft drink or juice (one part juice or soft drink to 5 parts water).
Do not drink undiluted lemonade or other undiluted soft drinks, as the high glucose content may draw fluid into the gut, causing more diarrhoea. Also, do not use sports rehydration drinks.
Other self-help measures include the following.
- Restrict food intake if you have gastroenteritis with vomiting. However, do not limit fluid intake. (Even if you vomit after drinking, you will likely absorb some fluid. If you don’t drink you will only get more dehydrated.) Children with gastroenteritis should be allowed to eat once they feel hungry.
- When you start eating, eat only bland, dry foods, avoiding grains and uncooked fruit and vegetables.
- Restrict consumption of fatty, sweet or spicy foods for 48 hours.
- Watch for signs of dehydration, especially in children and the elderly.
Some people may experience lactose intolerance (inability to digest milk sugars) for some time after the diarrhoea has settled. If this persists beyond a week or 2 you should seek medical assistance.
When should you seek medical advice?
Most people have experienced an episode of diarrhoea at some time in their lives. Generally, this resolves after a few days.
You should seek medical advice if:
- a child or elderly person has severe diarrhoea, as they may become rapidly dehydrated;
- diarrhoea lasts more than 5 days in a normal adult;
- there is bright red blood in the faeces, or stools are dark and tarry;
- the faeces have high fat content, which may be seen as pale, greasy, foul smelling stools that are difficult to flush;
- symptoms include fever, rash or stomach cramps, or a general feeling of being unwell;
- you have vomiting, weakness and dizziness;
- you have associated weight loss;
- there are signs of dehydration such as lethargy, loss of skin elasticity, dry mucous membranes, sunken eyes, decreased urine output, rapid heart rate or confusion;
- constipation alternates with the diarrhoea;
- the diarrhoea was acquired while travelling;
- the diarrhoea is associated with use of a medication and is not improving; or
- if you have a pre-existing medical condition such as type 1 diabetes, heart failure or kidney failure.
If your child has diarrhoea, take them to a doctor straight away if they have:
- symptoms of dehydration;
- diarrhoea lasting for more than 48 hours;
- vomiting that is stopping them from keeping down fluids;
- blood or pus in their stool;
- an associated rash;
- a fever above 38 degrees Celsius;
- severe pain in their abdomen; or if
- they are lethargic, cool, floppy, pale or unwell looking.
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