Illness and Symptoms

Giardia can be found in every region of the United States and around the world. You can get giardiasis if you swallow Giardia germs. Some people with giardiasis have no symptoms at all. If signs and symptoms develop, they may vary and usually begin 1 to 2 weeks after becoming infected with Giardia.

Short-term symptoms include:

  • Diarrhea
  • Gas
  • Foul-smelling, greasy stools (poop) that tend to float
  • Stomach cramps or pain
  • Upset stomach or nausea
  • Vomiting
  • Dehydration (loss of fluids)

Symptoms of giardiasis generally begin by having 2 to 5 loose stools per day, with progressively increasing fatigue. Other, less common symptoms include fever, itchy skin, hives, and swelling of the eyes and joints. Over time, giardiasis can also cause weight loss and keep the body from absorbing nutrients it needs, like fat, lactose, vitamin A, and vitamin B12. Some people with Giardia infections have no symptoms at all.

People with giardiasis will usually feel better and no longer have symptoms within 2 to 6 weeks. However, in some cases, symptoms may seem to be gone but will return after several days or weeks. Occasionally, people with giardiasis will have long-term complications such as reactive arthritis, irritable bowel syndrome, and recurring diarrhea that can last for years. Among children in particular, severe giardiasis may delay physical and mental growth, slow development, and cause malnutrition.