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  • Giardiasis (jee-ahr-DEYE-ah-sis), also known as traveler's diarrhea, is an infection that affects the small intestine (bowel). This infection is caused by a parasite (bug) called Giardia lamblia. The small intestine is a part of the digestive system where food is broken down. It is the tube that runs from the stomach to the colon (large intestine). With giardiasis, the parasite damages the lining of the small intestine and causes diarrhea (loose bowel movement). Giardiasis commonly occurs during summer and usually lasts for about 14 days. It is the most common cause of parasitic infection that affects travelers and campers.
    Picture of a normal digestive system
  • Signs and symptoms may include fever, vomiting (throwing up), nausea, or crampy abdominal (stomach) pain. You may also have dehydration (lose too much fluid) due to vomiting and diarrhea. Blood or stool (bowel movement) tests may be done to check if you have giardiasis. Treatment aims to replace the fluid that was lost to prevent dehydration. Your caregiver may also suggest that you take an antiparasitic medicine to kill the parasite. Giardiasis may be prevented by drinking only clean water and frequent hand washing. With treatment, such as medicine, and preventative measures, such as handwashing, the symptoms of giardiasis may be relieved and further problems prevented.


You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your caregivers to decide what care you want to receive. You always have the right to refuse treatment.


Not treating giardiasis may cause serious problems, such as malabsorption (not absorbing food and nutrients) and dehydration. Dehydration is when too much fluid and electrolytes (mineral salts) are lost from your body. When this happens, you may pass out or have seizures (convulsions). Your kidneys and other organs may not work properly and this may lead to death. With treatment, including medicines and fluids, you may be able to fully recover and resume normal activities. Ask your caregiver if you are worried or have questions about your infection, medicine, or care.


Informed consent:

A consent form is a legal document that explains the tests, treatments, or procedures that you may need. Informed consent means you understand what will be done and can make decisions about what you want. You give your permission when you sign the consent form. You can have someone sign this form for you if you are not able to sign it. You have the right to understand your medical care in words you know. Before you sign the consent form, understand the risks and benefits of what will be done. Make sure all your questions are answered.


  • You may not be able to eat solid food for a period of time. You may only be allowed to drink liquids to rest your intestines. You may drink water, broth, apple juice, or lemon-lime soda. You may also suck on ice chips or eat gelatin. As you improve, you may need to increase the amount of electrolytes, sugar, and proteins in your diet.
  • A caregiver, called a dietitian or nutritionist, may talk to you about the best liquids for you to drink. He may also give you an oral rehydration solution (ORS) to drink. An ORS has the right amounts of water, salts, and sugar your body needs to replace body fluids. You may also drink other liquids that have water, sugar, and salt, such as juices, milk, or sports drinks. These drinks may help prevent dehydration.

Intake and output:

Caregivers will keep track of the amount of liquid you are getting. They also may need to know how much you are urinating. Ask how much liquid you should drink each day. Ask caregivers if they need to measure or collect your urine.


An IV (intravenous) is a small tube placed in your vein that is used to give you medicine or liquids.


  • Antinausea medicine: This medicine may be given to calm your stomach and prevent vomiting.
  • Antiparasitic medicine: This medicine may be given to kill parasites. Parasites are living things that feed or eat off of other living things.


You may need any of the following tests to help caregivers plan your treatment.

  • Blood tests: You may need blood taken to give caregivers information about how your body is working. The blood may be taken from your hand, arm, or IV.
  • Stool sample: A sample of your stool or bowel movement (BM) is sent to a lab for tests. The stool may show what germ is causing your illness. This helps caregivers learn what medicine is best to treat you.

Treatment options:

You may have any of the following:

  • Oral rehydrating solutions: Caregivers may give you an oral rehydration solution (ORS) to drink. An ORS has the right amounts of water, salts, and sugar your body needs to replace body fluids. This may help prevent dehydration.
  • Intravenous therapy: If you are dehydrated, you may need to stay in the hospital to receive intravenous (IV) fluids. IV fluids are solutions that contain water, mineral salts, sugars, and proteins. These are given through a tube placed in a vein.

The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Learn more about Giardiasis (Inpatient Care)

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Symptoms and treatments