What is the role of medications in the treatment of giardiasis?

Updated: Oct 01, 2018
  • Author: Hisham Nazer, MBBCh, FRCP, DTM&H; Chief Editor: Burt Cagir, MD, FACS  more...
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Antibiotic therapy is standard in the treatment of giardiasis. [49, 73] Antimicrobial resistance has been reported.

Metronidazole is the antimicrobial agent most commonly used in the treatment of giardiasis in the United States. It has a cure rate of 85-90%.

Tinidazole is also approved in the United States and considered a first-line agent outside the United States. It is given in a single dose, the efficacy is reported at 90%, and it is believed to have fewer side effects than metronidazole. A common adverse effect is GI upset. A meta-analysis of 5 trials comprising 403 children regarding the efficacy of tinidazole versus albendazole treatment for pediatric giardiasis showed that tinidazole significantly outperformed albendazole. [65]

Paromomycin has been recommended for use in pregnancy because systemic absorption is low, but the cure rate is lower than with other agents.

Some drugs not available in the United States are considered effective therapeutic alternatives. Quinacrine achieves a cure rate of 90-95% but is available as an orphan drug in the US. The most common adverse effects include nausea, vomiting, and abdominal cramping. Occasional yellow discoloration of the skin, urine, and sclerae may occur. This medication should not be used in patients with documented hypersensitivity to this medication or related products, those diagnosed with psoriasis, or those with a history of psychosis.

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