Lethargy after Imidacloprid + Pyriproxyfen in cats

The FDA has received 73 reports of lethargy in cats after Imidacloprid + Pyriproxyfen. That is 11% of all reports for this medicine, compared with 14% across reports for all cat medicines.

73Reports
62%Marked serious
21%Recovered
11%Died or euthanised
8 daysTypical onset
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How soon it started

Same day
8 16%
1–2 days
13 26%
3–7 days
4 8.0%
1–4 weeks
16 32%
Over a month
9 18%

How the animals did

Recovered
15 21%
Still unwell when reported
5 6.8%
Died
3 4.1%
Euthanised
5 6.8%
Not known
45 62%

Problems reported at the same time

Age of the animals

Under 1 year
10
1–3 years
21
4–7 years
20
8–11 years
10
12+ years
8

About this medicine

Imidacloprid kills fleas (spot-on or collar).

Questions owners ask

Can Imidacloprid + Pyriproxyfen cause lethargy in cats?
73 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 8 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).

Lethargy with similar medicines

All reported side effects of Imidacloprid + Pyriproxyfen in cats · Medicines most reported with lethargy