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Giardiasis (cont.)

Giardia: Giardiasis Medications and Treatment

Patient Comments

Medications are used effectively to treat giardiasis.

Metronidazole (Flagyl)

  • This is the most common and most often recommended drug to treat giardiasis.
  • Treatment is highly effective with these pills, given 3 times a day for 5 days.
  • Side effects may include nausea, vomiting, headache, dry mouth, or a metallic taste in the mouth. Urine may turn dark or reddish-brown. Metronidazole brings on nausea and vomiting when alcohol is consumed while on the medication. Avoid alcohol 24 hours before starting the drug and for 48 hours after the last dose.


  • Treatment is highly effective with these pills, given over 5 days. Side effects may include nausea, vomiting, yellow skin and eyes, dark urine, and a rash.

Nitazoxanide (Alinia)

Other treatments

  • Tinidazole (Tindamax) is an oral single-dose antiprotozoal agent used in children

Pregnant women with giardiasis are treated somewhat differently because of the possible risk to the fetus by some of the medications.

  • If the disease is mild and dehydration can be avoided, treatment may be postponed until after delivery.
  • If treatment is necessary, paromomycin may be used but is less effective. The effects of metronidazole on the fetus appear to be minimal and occur mostly in the first trimester.
  • If therapy is necessary, metronidazole is probably safe to use in the second and third trimesters, but women should see their OB/GYN doctor before any treatment is started.

Giardia: Giardiasis Follow-up

The American Academy of Pediatrics recommends for daycare outbreaks that all employees and children improve their hand washing techniques and sanitation. All children, workers, and family members with symptoms of giardiasis should be treated. Children and staff members should be kept away from the center until they no longer have symptoms.

Medically Reviewed by a Doctor on 10/26/2016

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Read What Your Physician is Reading on Medscape

Giardiasis »

Giardia lamblia was originally identified by von Leeuwenhoek in the 1600s and was first recognized in human stool byVilem Dusan Lambl (1824-1895) in 1859and by Alfred Giard (1846-1908) after whom it is named.

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