Diarrhoea is a very common symptom with many possible causes. The term is used to describe an increase in frequency of bowel motions, or increased faeces liquidity, or sometimes a sense of faecal urgency. A textbook definition of diarrhoea is: "the passage of greater than 300 ml of liquid faeces in 24 hours". However, this is not a very useful definition, as faeces quantity is hardly ever measured.
 

Common Causes

As mentioned above, the causes of diarrhoea are too numerous to mention. To determine which causes are more likely, a doctor will need to know, amongst other things, a patient's normal bowel habit, and how long the diarrhoea has been present.

Treatment

1) Rehydration
Most adults with diarrhoea will not become dehydrated provided they take in adequate fluids. Fluids containing carbohydrates and electrolytes (e.g. fruit juice) are preferable.
In more severe diarrhoea, especially in children, dehydration can occur quickly and admission to hospital for intravenous fluids may be necessary.

2) Diet
It is generally accepted that people with diarrhoea find it more comfortable to rest the bowel by avoiding high-fibre foods, fats, milk products, caffeine and alcohol, instead taking in frequent small helpings of light meals and fluids.

3) Medicinal Treatment
The overwhelming majority of patients with diarrhoea will not need medicinal treatment. However, if there are symptoms or signs of a systemic illness and/or the symptoms are persisting, and particularly if bacteria are identified, then medicinal treatment may be required and will be prescribed by your doctor.
 

Summary

There are many possible causes of diarrhoea. Most commonly, it is a mild and self-limiting illness, but if symptoms are severe or persistent, one should seek help from a doctor as specific tests and/or treatment may be necessary.