Didn't stop worms after Pyrantel in horses

The FDA has received 142 reports of didn't stop worms in horses after Pyrantel. 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.

142Reports

1.4%Marked serious

2.8%Recovered

1.4%Died or euthanised

61 daysTypical onset

How soon it started

Same day

1 6.7%

1–2 days

2 13%

3–7 days

0 0.0%

1–4 weeks

1 6.7%

Over a month

11 73%

How the animals did

Recovered

4 2.8%

Still unwell when reported

6 4.2%

Died

2 1.4%

Not known

130 92%

Problems reported at the same time

Didn't work as expected

21 15%

Abdominal pain

17 12%

Itching

6 4.2%

Loss of condition

2 1.4%

Distension of abdomen

2 1.4%

Hair modification

2 1.4%

Weight loss

2 1.4%

Diarrhea

2 1.4%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Pyrantel treats roundworms and hookworms.

Questions owners ask

Can Pyrantel cause didn't stop worms in horses?: 142 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 61 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).

Didn't stop worms with similar medicines

Didn't stop worms after Fenbendazole 25 reports · 15% of its reports

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