WHO Model Prescribing Information: Drugs Used in Parasitic Diseases - Second Edition
(1995; 152 pages) [French] [Spanish] View the PDF document
Table of Contents
View the documentPreface
Close this folderProtozoa
Open this folder and view contentsAmoebiasis and giardiasis
View the documentBabesiosis
View the documentFree-living amoebae
Open this folder and view contentsLeishmaniasis
Open this folder and view contentsMalaria
View the documentMiscellaneous intestinal infection
Open this folder and view contentsPneumocystosis
Open this folder and view contentsToxoplasmosis
Open this folder and view contentsTrichomoniasis
Open this folder and view contentsAfrican trypanosomiasis
Close this folderAmerican trypanosomiasis
View the documentBenznidazole
View the documentNifurtimox
Open this folder and view contentsHelminths
View the documentSelected WHO publications of related interest
View the documentBack cover


Group: antiprotozoal agent
Scored tablet 100 mg

General information

Benznidazole is a trypanocidal nitroimidazole derivative which is rapidly absorbed from the alimentary tract. Peak plasma concentrations are reached after 2-4 hours and then decay with a half-life of approximately 12 hours. Benznidazole is partly metabolized in the body and all metabolites are rapidly eliminated in the urine and stools.

Clinical information


Treatment of acute American trypanosomiasis (Chagas disease). Cure rates of 80-90% have been recorded.

Dosage and administration

Adults: 5-7 mg/kg orally in two divided doses daily for 60 days.

Children (up to 12 years): 10 mg/kg orally in two divided doses daily for 60 days.

Contraindications and precautions

Patients with hepatic, renal or haematological insufficiency should receive the drug only under close medical supervision. The blood count, especially leukocytes, should be monitored throughout treatment and patients should be advised to abstain from alcohol.

Benznidazole should not be administered during early pregnancy.

Use in pregnancy

Safe use in pregnancy has not been established and treatment should be deferred until after the first trimester. It should then be instituted immediately to avoid the risk of congenital transmission.

Adverse effects

Adverse effects are frequent. Rashes may appear during the first 2 weeks of treatment. They are usually mild, but when they are severe and accompanied by fever and purpura, treatment should be definitively discontinued. Nausea may also occur during the initial phase of therapy.

Paraesthesiae or symptoms of peripheral polyneuritis are dose-related effects; if they occur treatment should be discontinued immediately.

More serious adverse effects include leukopenia and, rarely, agranulocytosis.


Tablets should be kept in well-closed containers, protected from light.

to previous section
to next section
The WHO Essential Medicines and Health Products Information Portal was designed and is maintained by Human Info NGO. Last updated: October 29, 2018