Loss of appetite after Imidacloprid + Pyriproxyfen in cats

The FDA has received 54 reports of loss of appetite in cats after Imidacloprid + Pyriproxyfen. That is 8.2% of all reports for this medicine, compared with 14% across reports for all cat medicines, so it is reported less often than average with this medicine.

54Reports
78%Marked serious
22%Recovered
20%Died or euthanised
7 daysTypical onset
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How soon it started

Same day
5 15%
1–2 days
7 21%
3–7 days
5 15%
1–4 weeks
12 36%
Over a month
4 12%

How the animals did

Recovered
12 22%
Still unwell when reported
4 7.4%
Died
6 11%
Euthanised
5 9.3%
Not known
27 50%

Problems reported at the same time

27 50%
24 44%
11 20%
11 20%
Dehydration
10 19%

Age of the animals

Under 1 year
11
1–3 years
10
4–7 years
13
8–11 years
8
12+ years
9

About this medicine

Imidacloprid kills fleas (spot-on or collar).

Questions owners ask

Can Imidacloprid + Pyriproxyfen cause loss of appetite in cats?
54 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 7 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).

Loss of appetite with similar medicines

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