Liver problems after Fenbendazole in dogs

The FDA has received 140 reports of liver problems in dogs after Fenbendazole. That is 2.4% of all reports for this medicine, compared with 4.6% across reports for all dog medicines, so it is reported less often than average with this medicine.

140Reports

72%Marked serious

13%Recovered

28%Died or euthanised

15 daysTypical onset

How soon it started

Same day

7 7.4%

1–2 days

15 16%

3–7 days

12 13%

1–4 weeks

34 36%

Over a month

27 28%

How the animals did

Recovered

17 12%

Recovered with lasting effects

1 0.7%

Still unwell when reported

50 36%

Died

20 14%

Euthanised

19 14%

Not known

33 24%

Problems reported at the same time

61 44%

59 42%

56 40%

40 29%

36 26%

36 26%

25 18%

24 17%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Fenbendazole treats intestinal worms and some other parasites.

Questions owners ask

Can Fenbendazole cause liver problems in dogs?: 140 reports link the two, but a report alone does not prove the medicine was the cause: other illnesses, other medicines or coincidence can be involved. Your vet can judge it for your animal.
How soon after a dose was it reported?: In half of the reports with dates, it started within 15 days of the first dose.
What should I do?: Don't give another dose until you've spoken to your vet, and keep the packaging so you can tell them the product and dose. Your vet can also report it to the FDA (or you can, through the manufacturer or FDA form 1932a).

Liver problems with similar medicines

Liver problems after Pyrantel + Sarolaner (Simparica Trio) 695 reports · 1.3% of its reports
Liver problems after Febantel + Praziquantel + Pyrantel (Drontal Plus) 70 reports · 1.0% of its reports
Liver problems after Pyrantel 126 reports · 2.6% of its reports
Liver problems after Praziquantel + Pyrantel 31 reports · 0.8% of its reports

All reported side effects of Fenbendazole in dogs · Medicines most reported with liver problems