Symptoms of Giardia Infection

Key points

  • Diarrhea is the most common symptom of Giardia infection.
  • Giardia can cause short-term symptoms, long-term symptoms, or no symptoms at all.
  • Talk to a healthcare provider if you think you may be sick from Giardia.
Man sitting on a couch holding his stomach in pain

Early symptoms

Symptoms often begin by having diarrhea 2 to 5 times per day and feeling more and more tired. However, Giardia infections do not always cause symptoms.

Common short-term symptoms include:

  • Diarrhea
  • Gas
  • Smelly, greasy poop that can float
  • Stomach cramps or pain
  • Upset stomach or nausea
  • Dehydration (loss of fluids)

Less common short-term symptoms include:

  • Fever
  • Itchy skin
  • Hives (skin rash with red, itchy bumps)
  • Swollen eyes
  • Swollen joints

How long symptoms last

Symptoms usually start 1 to 2 weeks after swallowing Giardia germs. They typically last for 2 to 6 weeks. Symptoms may last longer than 6 weeks, especially if you have a weakened immune system (for example, due to an illness such as HIV).

In some cases, symptoms may seem to be gone but will return after several days or weeks.

Complications

Occasionally, Giardia infection causes long-term symptoms that can last for years.

Complications and long-term symptoms can include:

  • Reactive arthritis (joint pain)
  • Irritable bowel syndrome, which causes stomach pain and other symptoms
  • Recurring diarrhea
  • Weight loss
  • Other symptoms caused by not being able to absorb nutrients, such as fat or vitamin B12

For children, a serious Giardia infection may:

  • Delay physical and mental growth
  • Slow development
  • Prevent them from absorbing nutrients from their food (malnutrition)
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Content Source:
National Center for Emerging and Zoonotic Infectious Diseases (NCEZID)