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HealthInfo Waitaha Canterbury


Mate tiāria

Giardia is a parasite (living thing) found in the guts of people and animals such as cattle, sheep, cats and dogs. It's also found in infected water such as lakes and streams.

You can get giardia (or giardiasis) if you swallow contaminated water. This can cause an infection called gastroenteritis.

Symptoms usually start seven to 10 days after being infected and usually last between three and four days.

The symptoms include diarrhoea, stomach pain or cramp, feeling sick and vomiting and a slight fever. Many people do not get any symptoms.

Diagnosing giardia

Giardia is diagnosed from a poo (faeces) sample.

If the tests find the giardia infection, your GP will report this to the local public health team. They may contact you for more information. This is to help stop the infection spreading further.

Treating giardia

Giardia is treated by a course of antibiotics such as metronidazole. You should also rest and drink plenty of fluids to prevent dehydration. See the self-care section on the gastroenteritis page for more details.

Getting help with giardia

You should see your GP if you have bloody diarrhoea or a fever or if your symptoms have not gone away after seven days. You should also see your GP if you're very unwell or if you have a weakened immune system.

You should take your child to your GP if they aren't drinking, if they're passing less urine than usual, have a dry mouth or sunken eyes or if they seem drowsy.

Avoiding spreading giardia

To reduce the risk of spreading the infection, it's important to have good hand hygiene. This includes washing your hands with soap and water, especially after using the toilet.

Try to avoid preparing food if you have giardia. If you do prepare food, make sure you wash and dry your hands well first. Follow this food safety advice.

Stay away from work, community gatherings and school or preschool until you or your child have been free of symptoms for 24 to 48 hours. This includes the last time you had diarrhoea.

You should wait for at least two weeks after the last episode of diarrhoea before you go swimming in a pool.

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Written by HealthInfo clinical advisers. Last reviewed May 2022.


See also:

Diarrhoea & vomiting in adults (gastroenteritis)

Diarrhoea & vomiting in children (gastroenteritis)

Eating and drinking when you're unwell

Page reference: 49689

Review key: HIGTE-81185