Why does giardiasis cause diarrhoea?

The parasite attaches to the lining of the small intestine. This can interfere with the gut's usual job of absorbing water and nutrients from food. The result may be frequent loose stools, urgency, cramps, wind or stools that look greasy and smell unusually strong. Diarrhoea is a very common presentation of Giardiasis; however, diarrhoea can also result from many infections, foods and medicines.

A change in digestion can continue for a while, so symptoms may fluctuate rather than following a neat pattern each day.

Replace fluids steadily, taking small frequent sips if your stomach feels unsettled. Oral rehydration solution can help replace salts lost with loose stools. Wash hands carefully after using the toilet and before preparing food to reduce spread. A clinician can assess your history and may request a stool sample to look for the parasite.

Do not use medicines intended to stop diarrhoea without checking first if you have fever, blood in the stool, or significant abdominal pain.

Get urgent help for confusion, fainting, severe weakness, blood or black stools, severe abdominal pain, repeated vomiting, or dehydration such as very little urine and persistent dizziness. Contact a clinician promptly when diarrhoea lasts, disrupts drinking or eating, follows possible contaminated water exposure, or affects an infant, older adult, pregnant person, or someone with reduced immunity.

Ask whether testing is appropriate, whether you need treatment for a confirmed infection, and how to prevent passing it to people at home. Ask what symptoms would mean you need a further examination.