Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.
About Giardia Infections
Giardiasis is an illness caused by a parasite called Giardia intestinalis. It lives in soil, food, and water. It may also be on surfaces that have been contaminated with waste. You can become infected if you swallow the parasite. You can also get it if you're exposed to human feces (poop) through sexual contact.
The risk of getting giardia is higher for travelers to countries where it is common, people in child care settings, and those who drink untreated water.
Diarrhea is the main symptom of giardia infection. Others include:
- Passing gas
- Greasy stools
- Stomach cramps
- Upset stomach or nausea
These symptoms may lead to weight loss and loss of body fluids. Some people have no symptoms at all. Symptoms of infection often last two to six weeks. Stool sample tests can diagnose it. You often need to collect several samples to test. Doctors use several drugs to treat it.
The best way to prevent giardia infection is to practice good hygiene, including frequent hand washing. You should not drink water that may be contaminated. You should also peel or wash fresh fruit and vegetables before eating.
Centers for Disease Control and Prevention
It sits within Infections.
The lead U.S. institute for this subject is the National Institute of Allergy and Infectious Diseases.
When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.
Research on Giardia Infections
14 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.
What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.
Research currently under way
- Risk Assessment of Community Spread of Multiple Endemic Infectious Diseases in a One Health PerspectiveInstitut Pasteur du Cambodge
- Anti-protozoal Effect of Steroid Hormone 20-hydroxyecdysoneResearch Institute of Epidemiology, Microbiology and Infectious Diseases, Uzbekistan
- A Comparison of Microscopy and Enzyme Linked Immunosorbent Assay for Diagnosis of Giardia Lamblia in Children, SohagSohag University
Research already completed
- Auranofin for Giardia ProtozoaNational Institute of Allergy and Infectious Diseases (NIAID)
- Intestinal Parasites in Inhabitants of Kuyavian-Pomeranian Province in PolandNicolaus Copernicus University
- Giardia Induced Fatigue and Functional Gastrointestinal DiseasesUniversity of Bergen
- Diagnosis of Neglected Tropical Diseases Among Patients With Persistent Digestive DisordersSwiss Tropical & Public Health Institute
- Surveillance and Medical Help for HIV-infected Intravenous Drug Users in and Out of PrisonKaohsiung Medical University Chung-Ho Memorial Hospital
- Impact of Anti-Giardia and Antihelmintic Treatment on Infant Growth in BangladeshUniversity of Cambridge
Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.
Where to read more
Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.
Start Here
- About GiardiaCenters for Disease Control and Prevention
- Giardia Infection (Giardiasis)Mayo Foundation for Medical Education and Research
- GiardiasisAmerican Academy of Family Physicians
Symptoms
- Symptoms of Giardia InfectionCenters for Disease Control and Prevention
Diagnosis and Tests
- Diagnosis of Parasitic DiseasesCenters for Disease Control and Prevention
- Ova and Parasite TestNational Library of Medicine
- String test for intestinal parasitesMedical Encyclopedia
Treatments and Therapies
- Treatment of Giardia InfectionCenters for Disease Control and Prevention
Prevention and Risk Factors
- Giardia Infection Prevention and ControlCenters for Disease Control and Prevention
Related Issues
- About Giardia and PetsCenters for Disease Control and Prevention
- Germs That Can Contaminate Tap WaterCenters for Disease Control and Prevention
- Water Disinfection for TravelersCenters for Disease Control and Prevention
Clinical Trials
- ClinicalTrials.gov: GiardiasisNational Institutes of Health
Medical subject headings
Clinicians and researchers index this subject under Giardiasis. These are the terms to use when searching medical literature.
This page is built from the MedlinePlus health topic record for Giardia Infections, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.