Giardiasis

A gut infection with the parasite Giardia, causing greasy diarrhoea, bloating and gas.

InfectionDigestionLast updated: 21 October 2026

Quick Summary

Primary Symptoms

Watery or greasy, foul-smelling diarrhoea, bloating, gas, tummy cramps, nausea and weight loss.

Common Treatments

Antiparasitic medicines such as metronidazole or tinidazole, and fluids.

Risk Factors

Drinking untreated water, poor hygiene, childcare settings and travel.

OverviewSymptomsCausesTreatmentFAQ

Overview

Giardia spreads through water, food or hands contaminated with infected stool.

Symptoms can last weeks and may cause temporary lactose intolerance.

Symptoms

Diarrhoea

Greasy, smelly stools.

Bloating and gas

Burping.

Cramps

And nausea.

Weight loss

With long-lasting infection.

Causes & Risk Factors

Biological Causes

Infection with Giardia lamblia.

Key Risk Factors

  • Unsafe water Including wells and streams.
  • Children In nurseries.
  • Hygiene Poor handwashing.

Management & Treatment

01. Medicines

Metronidazole or tinidazole.

02. Fluids

Prevent dehydration.

03. Hygiene

Handwashing to prevent spread.

Frequently Asked Questions

Is it contagious?
Yes, through contaminated hands and water.
How is it diagnosed?
With stool tests.

Sources and further reading

Last updated 21 October 2026. For more detail, see these trusted health organisations.