Giardiasis (Giardia Lamblia Infection): Symptoms & Signs

  • Medical Author:
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Medically Reviewed on 6/1/2017

Signs and symptoms of giardiasis can vary, and some people may be infected without showing any symptoms. Symptoms, when they occur, can last two weeks or longer. The most common symptoms are

  • diarrhea,
  • gas,
  • fatty or foul-smelling stools (they may float), and
  • stomach or abdominal cramping.

Nausea and vomiting may occur along with malaise, fatigue, and bloating. The symptoms together can lead to dehydration. Less common symptoms may include

If untreated, the infection can persist for months to years. Over time, giardiasis can cause weight loss, malnutrition, and delayed development in children.

Causes of giardiasis

Giardiasis is caused by infection with the Giardia lamblia parasite.

Related Symptoms & Signs


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.

Medically Reviewed by a Doctor on 6/1/2017
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