Didn't stop worms after Fenbendazole in horses

The FDA has received 25 reports of didn't stop worms in horses after Fenbendazole. That is 15% of all reports for this medicine, compared with 2.1% across reports for all horse medicines, so it is reported unusually often with this medicine.

25Reports

32%Marked serious

4.0%Recovered

12%Died or euthanised

–Typical onset

How the animals did

Recovered

1 4.0%

Still unwell when reported

11 44%

Died

2 8.0%

Euthanised

1 4.0%

Not known

10 40%

Problems reported at the same time

Death

3 12%

Didn't work as expected

2 8.0%

Overdose

1 4.0%

Fever

1 4.0%

Recumbency

1 4.0%

Loss of appetite

1 4.0%

Weight loss

1 4.0%

Lymphoma

1 4.0%

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 didn't stop worms in horses?: 25 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.
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).

Didn't stop worms with similar medicines

Didn't stop worms after Pyrantel 142 reports · 15% of its reports

All reported side effects of Fenbendazole in horses · Medicines most reported with didn't stop worms