Blood test for giardia: what to know

Giardia can cause watery or greasy diarrhoea, abdominal cramps, bloating, nausea, and tiredness after contaminated water, food, or contact. A stool sample can be examined for the parasite or its markers. Blood work may check hydration, salts, blood counts, or other explanations for prolonged diarrhoea, but it does not normally identify an active intestinal infection. A negative stool result may not settle the question if symptoms continue, so the clinician may request another sample or consider other conditions.

Drink frequent small amounts of safe fluid and follow the collection instructions carefully. Wash hands with soap after using the toilet and before preparing food, and avoid swimming while diarrhoea continues. Tell the clinician about travel, untreated water, household illness, and recent antibiotics. Do not start anti-parasitic medicine without advice, especially if you are pregnant, treating a child, or have another medical condition.

Seek urgent care for severe dehydration, very little urine, fainting, blood in stool, severe abdominal pain, persistent vomiting, confusion, or diarrhoea in a vulnerable person. Arrange medical review when symptoms persist, recur, or cause difficulty maintaining fluids. A blood test can support a wider assessment, but worsening symptoms need clinical attention regardless of the test result.

Should I provide a stool sample, and how should it be stored? Could another infection or condition explain the symptoms? How can I replace fluids safely? When should I return if diarrhoea continues?