Is giardiasis contagious?

Transmission occurs when tiny parasite forms leave an infected person in stool and later reach someone’s mouth. This can happen through shared bathrooms, close household contact, sexual contact involving the anus, unsafe drinking water, or food handled without good hand hygiene. A person may spread infection even when symptoms are mild or absent.

Symptoms can include diarrhoea, abdominal cramps, bloating, gas, nausea, and fatigue. Learn more about [Giardiasis](/conditions/giardiasis/), [Bloating](/symptoms/bloating/), and [Abdominal Pain](/symptoms/abdominal-pain/).

Wash hands with soap and water after using the toilet, changing nappies, or helping someone in the bathroom, and before eating or preparing food. Clean frequently touched bathroom surfaces, avoid sharing towels, and wash soiled clothing and bedding separately when practical. Use safe drinking water and avoid preparing food for others while diarrhoea continues. Ask a clinician about testing and treatment through a [GP Consultation](/treatments/consultations-and-assessment/gp-consultation/).

Arrange medical advice for ongoing diarrhoea, repeated symptoms, weight loss, or signs of dehydration such as dizziness, dry mouth, or reduced urination. Seek urgent help for severe weakness, confusion, severe abdominal pain, or inability to keep fluids down. Contact a clinician promptly if an infant, older adult, pregnant person, or immunocompromised person may be infected.

Ask whether household or travel contacts need assessment, how long you should take extra hygiene precautions, and whether [Antibiotic Treatment](/treatments/medical-management/antibiotic-treatment/) is suitable for your situation.