Antiprotozoals for giardiasis

Examples

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Brand Name	Chemical Name
Protostat	metronidazole

Brand Name	Chemical Name
Tindamax	tinidazole

How It Works

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These medicines kill Giardia lamblia in the gastrointestinal tract.

Metronidazole comes in tablet and liquid forms. It usually is taken in tablet form for 3 to 7 days for treatment of giardiasis.

Tinidazole comes in tablet form. It usually is taken for 1 day in either one or several doses throughout the day.

Why It Is Used

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These medicines are used to treat certain bacterial and parasite infections. They also are an effective treatment for giardiasis infection.

These medicines may be used if stool analysis or other testing indicates giardiasis infection.

In those cases where it is very likely the symptoms are caused by giardia, your doctor often will prescribe one of these medications even before your test results are back.

Talk with your doctor or pharmacist before taking these medications if you are pregnant.

How Well It Works

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Metronidazole cures giardiasis in adults 80% to 95% of the time.¹

Tinidazole is very effective for the treatment of giardiasis—a single dose often cures the infection with very few side effects.²

Side Effects

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The most common side effects of these medicines include:

• A metallic taste in the mouth.
• Nausea, vomiting.
• Dizziness.
• Headache.

A low number of white blood cells (neutropenia, leukopenia) is a rare side effect. The white blood cell count returns to normal when you stop taking the drug.

Do not drink alcohol while you are taking metronidazole or tinidazole. Using alcohol while you are taking these medicines can cause headaches, nausea, reddening of the face, belly cramps, and vomiting. You should also avoid alcohol for at least 3 days after you finish your last dose of these medicines.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

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Metronidazole may be used with caution in pregnant women.

Tinidazole has only recently been approved by the U.S. Food and Drug Administration (FDA) for the treatment of giardiasis, although it has been available in other parts of the world.

Do not use alcohol while you are taking either of these medications or for 3 days after you finish your last dose.

Complete the new medication information form (PDF) (What is a PDF document?) to help you understand this medication.

References

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Citations

1. Hill DR (2005). Giardia lamblia. In GL Mandell et al., eds., Principles and Practice of Infectious Disease, 6th ed., vol. 2, pp. 3198–3205. Philadelphia: Elsevier.

2. Zaat JO, et al. (2005). Drugs for treating giardiasis. Cochrane Database of Systematic Reviews (2). Oxford: Update Software.

Credits

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Author	Colleen Cronin
Editor	Susan Van Houten, RN, BSN, MBA
Associate Editor	Michele Cronen
Associate Editor	Tracy Landauer
Primary Medical Reviewer	Adam Husney, MD - Family Medicine
Specialist Medical Reviewer	W. David Colby, MSc, MD, FRCPC - Infectious Disease
Last Updated	October 19, 2005