Didn't stop worms after Imidacloprid + Pyriproxyfen in cats

The FDA has received 50 reports of didn't stop worms in cats after Imidacloprid + Pyriproxyfen. That is 7.6% of all reports for this medicine, compared with 1.8% across reports for all cat medicines, so it is reported unusually often with this medicine.

50Reports

24%Marked serious

10%Recovered

2.0%Died or euthanised

20 daysTypical onset

How soon it started

Same day

0 0.0%

1–2 days

2 7.4%

3–7 days

2 7.4%

1–4 weeks

11 41%

Over a month

12 44%

How the animals did

Recovered

5 10%

Still unwell when reported

4 8.0%

Euthanised

1 2.0%

Not known

40 80%

Problems reported at the same time

29 58%

15 30%

11 22%

6 12%

5 10%

Application site reaction

5 10%

Vomiting

4 8.0%

Lethargy

4 8.0%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Imidacloprid kills fleas (spot-on or collar).

Questions owners ask

Can Imidacloprid + Pyriproxyfen cause didn't stop worms in cats?: 50 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 20 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 Imidacloprid + Moxidectin (Advantage Multi) 77 reports · 0.9% of its reports
Didn't stop worms after Flumethrin + Imidacloprid (Seresto) 21 reports · 3.1% of its reports

All reported side effects of Imidacloprid + Pyriproxyfen in cats · Medicines most reported with didn't stop worms