Dehydration after Fenbendazole in dogs

The FDA has received 97 reports of dehydration in dogs after Fenbendazole. That is 1.6% of all reports for this medicine, compared with 0.7% across reports for all dog medicines, so it is reported unusually often with this medicine.

97Reports

68%Marked serious

12%Recovered

27%Died or euthanised

6 daysTypical onset

How soon it started

Same day

10 18%

1–2 days

8 14%

3–7 days

15 26%

1–4 weeks

15 26%

Over a month

9 16%

How the animals did

Recovered

11 11%

Recovered with lasting effects

1 1.0%

Still unwell when reported

25 26%

Died

14 14%

Euthanised

12 12%

Not known

34 35%

Problems reported at the same time

51 53%

48 49%

47 48%

32 33%

25 26%

Didn't work as expected

22 23%

Weight loss

17 18%

Liver problems

17 18%

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 dehydration in dogs?: 97 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 6 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).

Dehydration with similar medicines

Dehydration after Pyrantel + Sarolaner (Simparica Trio) 212 reports · 0.4% of its reports
Dehydration after Febantel + Praziquantel + Pyrantel (Drontal Plus) 44 reports · 0.7% of its reports
Dehydration after Pyrantel 75 reports · 1.6% of its reports
Dehydration after Praziquantel + Pyrantel 20 reports · 0.5% of its reports

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