Diarrhoea is when your poos become runny or watery or you have to poo a lot more often. It is very common in adults and children.
Key points about diarrhoea
- Diarrhoea can start suddenly and last for less than 2 weeks (acute) or last for more than 2 weeks (chronic).
- The most common cause of diarrhoea is gastroenteritis or infection (eg, food poisoning or viral infection passed on by someone).
- Diarrhoea usually goes away on its own, but if you have the symptoms below you need to seek medical attention.
- The main complication of diarrhoea is dehydration (being very thirsty from losing too much water).
- Treatment depends on the cause of your diarrhoea.
- There are things you can do to prevent the spread of diarrhoea.
See your GP, go to the nearest emergency department or call 111 for an ambulance immediately if you or someone you care for experiences any of the following:
You should also bring your child to your GP, emergency department or call 111 for an ambulance if they:
Call Healthline 0800 611 116 or Plunketline 0800 933 922 if you are unsure what to do.
What is diarrhoea?
Diarrhoea is when your poos become loose, runny or watery, or you have to poo a lot more often. The definition of diarrhoea is different for everyone, as your normal poos may be different from someone else’s.
Diarrhoea can be:
- acute, which starts off suddenly and lasts for less than 2 weeks
- chronic, which means your diarrhoea lasts for more than 2 weeks.
What are the causes of diarrhoea?
One of the important roles of healthy bowel is to reabsorb water from your poo. With diarrhoea, your bowel can’t do this. As a result, your poo becomes watery and extra water is lost from your body. This fluid loss can lead to dehydration.
People can become dehydrated very quickly if they don’t drink enough fluids when they have diarrhoea. Children and elderly people are more at risk.
Diarrhoea has many possible causes, depending on whether it is acute or chronic.
Causes of acute diarrhoea
- infection of your gut (gastroenteritis) – this is the most common cause of acute diarrhoea in adults and children and may be spread by contaminated food or water, or from person-to-person contact
- other infections such as HIV infection
- anxiety or stress
- food intolerance or a food allergy
- side effects of some medicines or chemotherapy
- constipation – ongoing constipation can cause overflow diarrhoea which can also lead to faecal incontinence (losing control of your bowel)
- too much alcohol or coffee.
Causes of chronic diarrhoea
- chronic gut infection
- colitis – inflammation of your colon (large intestine) due to causes such as ischaemia (lack of blood supply)
- diverticular disease
- chronic pancreatitis
- having had bowel surgery
- inflammatory bowel disease such as Crohn’s disease or ulcerative colitis
- coeliac disease
- food intolerance or allergy such as lactose intolerance or cow’s milk protein allergy
- irritable bowel syndrome
- colon cancer
- side effects of some medicines or chemotherapy
- malabsorption syndrome.
What are the symptoms of diarrhoea?
Diarrhoea is experienced as watery bowel movements (poo) which may last for a few days.
Your diarrhoea can be:
- accompanied by pus or fat
You may also have other symptoms, such as:
- painful stomach cramps
- flatulence (wind)
- weakness or fatigue
- nausea (feeling sick) or vomiting (being sick)
- loss of appetite
- a headache
- an urgent need to go to the toilet.
What are the complications of diarrhoea?
The main complication of diarrhoea is dehydration. Dehydration is the loss of water and salts from your body. Most people experience mild dehydration, but if it becomes severe it can lead to death.
Babies under 1 year old and older adults are most at risk of getting dehydrated from diarrhoea.
In the early stages of dehydration (mild dehydration), symptoms include:
- a dry, sticky mouth and tongue
- feeling lightheaded or dizzy
- a headache
- feeling very tired – no energy.
As dehydration becomes worse (moderate or severe dehydration), symptoms include:
- extreme thirst
- dry mouth and cracked lips
- urinating (peeing) less
- not peeing for 8 hours (a sign of severe dehydration)
- dizziness when you stand up that doesn't go away after a few seconds
- feeling sleepy, tired or confused
- cramping in your arms and legs.
If you have signs of moderate or severe dehydration, see your doctor, go to the nearest emergency department or call 111 for an ambulance immediately.
How are the causes of diarrhoea diagnosed?
Your doctor will ask you questions about your diarrhoea, including whether you have other symptoms, any medical illness in the past or whether you have travelled anywhere. Your doctor will also ask if you have been in contact with someone with similar symptoms and whether you are taking any medicines.
Your doctor will also examine your tummy and check for signs of dehydration. Usually, no tests are needed to diagnose the cause of your diarrhoea, but, if you are really unwell or have bloody diarrhoea, your doctor may ask you to provide a stool (poo) sample to check for the bug causing your infection. If you have chronic diarrhoea, other tests such as blood tests or an endoscopy may be done to look at your intestine.
Testing may also be needed if your diarrhoea has lasted longer than 5 days, or if you work in certain industries (eg, food handling, childcare or health care).
How is diarrhoea treated?
Diarrhoea is usually self-limiting and will go away by itself in a few days. Treatment will depend on the cause of your diarrhoea.
Generally, treatment of diarrhoea includes:
If you have diarrhoea, the most important treatment is to keep your fluid intake up. Try to drink small amounts of water often. Oral rehydration solutions available from your pharmacy (chemist) are useful because they also replace vital salts. Avoid fizzy or sugary drinks, fruit juice and milk. For 48 hours, try to eat bland, non-greasy foods or soups. Avoid grains, uncooked fruits or vegetables, and alcohol.
Read more about self-care for diarrhoea.
Medicines that may be used to treat diarrhoea include:
- antidiarrhoeal medicines
- oral rehydration salts
- intravenous fluids.
Anti-diarrhoeal medicines slow the movement of your gut, reduce the number of bowel motions and firm up runny poos. However, they don’t cure the cause of your diarrhoea. An example of anti-diarrhoeal medicine is loperamide.
These medicines should not be given to babies or children. Ask your doctor or pharmacist for advice on whether you should take them.
Antibiotics are rarely needed. They are only needed to treat diarrhoea in some circumstances, such as certain infectious causes. Not all infectious diarrhoea requires antibiotic treatment as most bacterial gut infections are self limiting (get better on their own). Your doctor will let you know if you need antibiotics for your diarrhoea.
Oral rehydration salts
Oral rehydration salts are a mixture of electrolytes (salts) and carbohydrates (in the form of sugar), which are dissolved in water. They are used to replace salts and water that your body loses when you have dehydration due to diarrhoea. These can be purchased over the counter from your local pharmacy (chemist). Read more about oral rehydration salts.
Intravenous (IV) fluids
IV fluids are needed if you have severe dehydration and are admitted to the hospital. Fluids will be given through your vein to replenish your fluids and salts faster. IV fluids may be given in hospital, GP or urgent care clinics.
How can I care for myself with diarrhoea?
Some self-care measures that you can do when you have diarrhoea include:
- getting plenty of rest
- drinking small amount of fluids often
- taking paracetamol if you also have fever or stomach pain
- putting a hot water bottle or heat pack on your stomach to relieve pain
- eating normally, if possible, but avoiding rich or high-fat foods
- avoiding tea, coffee, alcohol and dairy products
- avoiding fatty, oily or sugary food and drinks
- avoiding undiluted fruit juices
- taking oral rehydration salts if needed (these are available at local pharmacies without prescription).
Take care to prevent the spread of diarrhoea. Regular and thorough handwashing is very important.
How can I care for my child with diarrhoea?
If your child has diarrhoea, the main treatment is to make sure your child is drinking enough fluids. Offer them small amounts of fluid often (aim for about one-quarter of a cup every 15 minutes). Keep offering your child fluids even if they are vomiting.
Which fluids should I give my child?
- If you are breastfeeding, continue this. You may need to feed more often and you may need to give extra fluid.
- An oral rehydration solution is good to give your child when they are dehydrated – you can buy child formulations from your local pharmacy.
- Milk formula at normal strength, or cows’ milk if your child is over 1 year old.
- Clear, thin soups or flat, diluted lemonade (1 part to 5 parts warm water).
Do NOT give undiluted soft drinks, fruit juice, sports drinks, Lucozade and Ribena, as too much sugar makes diarrhoea and dehydration worse.
What foods can I give my child?
Children should be offered food if they are hungry, even if they still have diarrhoea. Your child may refuse food at first. This is not a problem as long as they are drinking fluids. If possible, don't stop food for more than 24 hours.
Try giving them foods such as bread/toast, rice, porridge, milk pudding, yoghurt. Avoid high sugar or fatty foods.
Can I give my child anti-diarrhoeal medicines?
Do not give your child medicines to reduce diarrhoea – they may be harmful to children. See your doctor if you are concerned about your child's symptoms.
Take care to prevent the spread of diarrhoea.
The following links provide further information about diarrhoea. Be aware that websites from other countries may have information that differs from New Zealand recommendations.
Diarrhoea Ministry of Health, NZ
Diarrhoea and vomiting (gastroenteritis) HealthInfo Canterbury, NZ
Gastroenteritis in children KidsHealth NZ
Diarrhoea Health Direct, Australia
Diarrhoea Patient Info, UK
Diarrhoea and vomiting NHS, UK
- Investigating and managing people with diarrhoea BPAC, NZ, 2014
- Acute diarrhoea in adults Patient Info, UK
|Dr Arna Letica has worked as a GP for over 13 years, with particular interests in women's and children's health. She is currently focusing on non-clinical roles, including working as a medical assessor.|