Methadone — FDA Animal & Veterinary Adverse Event (ADE) Reports
Source: openFDA animalandveterinary/event.json, the FDA Center for Veterinary Medicine (CVM) adverse event report database. Data pulled 2026-07-22. Counts are report-level: one report may list multiple reactions and multiple animals, so figures are not additive and do not imply causation. Methadone is a active ingredient.
Total reports
Methadone: 323
Reports by species (top entries)
- Dog 225
- Cat 93
- Human 2
- Deer 1
- Pig 1
- Rabbit 1
Top reported reactions (VEDDRA terms, top entries)
- Lethargy (see also Central nervous system depression in Neurological) 49
- Not eating 44
- Death by euthanasia 40
- Death 35
- Diarrhoea 35
- Vomiting 33
- Hypotension 31
- Fever 29
- Anorexia 26
- Other abnormal test result NOS 26
Source JSON: pdf-raw/ade/ade_active_ingredients_2026-07-22_b16.json (openFDA animalandveterinary/event.json, pulled 2026-07-22).