What the label lists and what reports show
Benznidazole side effects
Benznidazole's FDA label: “Most common adverse reactions observed were abdominal pain, rash, decreased weight, headache, nausea, vomiting, neutropenia, urticaria, pruritus, eosinophilia, decreased appetite ( 6.1 ).” FAERS holds 100 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is rash (18 reports).
- No generic listed
Check it at the source: the benznidazole FDA label on DailyMed (effective August 27, 2026, Exeltis USA, Inc.); the FDA FAERS public dashboard.
What does the label list?
From the label: adverse reactionsMost common adverse reactions observed were abdominal pain, rash, decreased weight, headache, nausea, vomiting, neutropenia, urticaria, pruritus, eosinophilia, decreased appetite ( 6.1 ).
Table 4: Adverse Reactions Occurring in Pediatric Patients with Chagas Disease aged 6 to 12 Years in Trial 1
| Adverse Reaction | Benznidazole (N=55) N (%) | Placebo (N=51) N (%) |
|---|---|---|
| Abdominal pain | 14 (25) | 4 (8) |
| Rash | 9 (16) | 0 |
| Transaminases increased | 3 (5) | 0 |
| Dizziness | 2 (4) | 2 (4) |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe following serious and otherwise important adverse reactions are discussed in greater detail in other sections of labeling: Potential for Genotoxicity, Carcinogenicity, and Mutagenicity [see Warnings and Precautions ( 5.1 )] Hypersensitivity Skin Reactions [see Warnings and Precautions ( 5.3 )] Central and Peripheral Nervous System Effects [see Warnings and Precautions ( 5.4 )] Hematological Manifestations of Bone Marrow Depression [see Warnings and Precautions ( 5.5 )] Most common adverse reactions observed were abdominal pain, rash, decreased weight, headache, nausea, vomiting, neutropenia, urticaria, pruritus, eosinophilia, decreased appetite ( 6.1 ). To report SUSPECTED ADVERSE REACTIONS, contact Exeltis USA, Inc. at 1-877-324-9349 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trial Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Benznidazole was evaluated in two randomized, double-blind, placebo-controlled trials (Trial 1 1 and Trial 2 2 ) and one uncontrolled trial (Trial 3 3 ). Trial 1 was conducted in pediatric patients 6 to 12 years of age with chronic indeterminate Chagas disease in Argentina. …
Source: FDA drug label, NDA209570 (Chemo Research Sl), as published by Exeltis USA, Inc., effective August 27, 2026 (SPL set 8983d6a0-f63f-4f8e-bba4-38223f39e29b), via openFDA; the full label on DailyMed
What do FAERS reports show?
100 reports list benznidazole among the medicines taken, each a report of something that happened, not proof the medicine caused it; 5 are coded as a death and 27 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 19 reactions below, 10 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Benznidazole: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions