What happens if giardiasis is not treated?

Giardiasis is an intestinal infection caused by a microscopic parasite. It can lead to frequent or loose stools, cramps, bloating, gas, nausea and tiredness. Some people notice greasy or unusually foul-smelling stools, while others have milder symptoms. If the infection continues, fluid loss can build up and eating may become difficult.

The bowel can remain sensitive after the infection has cleared, so diarrhoea or bloating may not stop immediately after treatment. People can also pass the parasite to others through contaminated hands, food or water. Children, older adults and people who are medically vulnerable may become dehydrated more quickly.

Arrange a GP consultation if diarrhoea continues, especially after travel, unsafe water exposure, childcare contact or a household illness. The clinician may request stool testing and will consider other causes of persistent bowel symptoms. Antibiotic treatment or another prescription may be advised when giardiasis is confirmed or strongly suspected.

Drink frequent small amounts of fluid; oral rehydration solution can help replace water and salts when losses are significant. Wash hands carefully after using the toilet and before preparing food, avoid sharing towels, and do not prepare food for others while you have diarrhoea. Follow any treatment instructions fully.

Seek urgent medical advice if you cannot keep fluids down, pass very little urine, feel faint or confused, have severe abdominal pain, blood in the stool, or marked weakness. Get prompt advice for a young child, pregnancy, frailty or a weakened immune system, because dehydration can become serious.

Ask whether stool testing is needed, how to replace fluids, which treatment is suitable, when you can return to work or school, and whether household or travel contacts need advice.