Lethargy after Imidacloprid in cats

33 reports to the FDA describe lethargy in cats given Imidacloprid. That is 13% of all reports for this medicine, compared with 14% across reports for all cat medicines.

33Reports
55%Marked serious
36%Recovered
27%Died or euthanised
4 daysTypical onset
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How soon it started

Same day
8 28%
1–2 days
5 17%
3–7 days
3 10%
1–4 weeks
7 24%
Over a month
6 21%

How the animals did

Recovered
9 27%
Recovered with lasting effects
3 9.1%
Still unwell when reported
4 12%
Died
5 15%
Euthanised
4 12%
Not known
8 24%

Problems reported at the same time

10 30%
Death
9 27%
Tremors
7 21%
Fever
5 15%
Wobbliness (ataxia)
4 12%
Seizures
4 12%

Age of the animals

Under 1 year
4
1–3 years
10
4–7 years
7
8–11 years
5
12+ years
6

About this medicine

Imidacloprid kills fleas (spot-on or collar).

Questions owners ask

Can Imidacloprid cause lethargy in cats?
33 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 4 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 in cats · Medicines most reported with lethargy