What should you know about acute giardiasis?

It spreads when Giardia from faeces is swallowed through contaminated water, food, hands, surfaces, or close contact. Hydration matters, and a clinician may confirm the infection with stool testing and prescribe an antiparasitic medicine.

Giardia lives in the small intestine and can interfere with normal digestion and absorption. Stools may become loose, foul-smelling, pale, or oily, while increased gas and bloating can make meals uncomfortable. Fever and bloody diarrhoea are not typical features and may point to another or additional problem.

Exposure can occur after swallowing untreated water, recreational water, or food handled with contaminated hands. Infection can also pass between people when hand hygiene is poor, particularly around toileting or nappy changing.

Drink regularly to replace fluid lost through diarrhoea. Choose foods according to appetite, and note whether dairy products temporarily worsen cramps or loose stools. Contact a GP if giardiasis is possible; diagnosis may require stool samples, and prescribed treatment should be taken exactly as directed.

Use soap and water after using the toilet or changing nappies and before preparing food. Do not swim while you have diarrhoea, avoid swallowing pool or open-water water, and keep bathroom surfaces clean. Household members with symptoms may need their own assessment rather than sharing medicine.

Get urgent medical help for marked drowsiness or confusion, fainting, very little urine, inability to retain drinks, severe or increasing abdominal pain, or blood or black stool. These signs can indicate significant dehydration or a condition other than uncomplicated giardiasis.

Seek timely assessment when diarrhoea persists, symptoms return after treatment, weight is falling, or eating and drinking remain difficult. Earlier advice is sensible for infants, pregnant people, older adults, and anyone with a weakened immune system because fluid loss can affect them more quickly.

Tell your doctor about untreated water, swimming, travel, childcare contact, similar illness at home, and previous treatment. Useful questions include how to collect stool samples, whether your medicines need adjustment, when you may safely return to shared activities, and what to do if symptoms continue.