Didn't stop fleas after Imidacloprid in cats

104 reports to the FDA describe didn't stop fleas in cats given Imidacloprid. That is 41% of all reports for this medicine, compared with 8.4% across reports for all cat medicines, so it is reported unusually often with this medicine.

104Reports
1.9%Marked serious
4.8%Recovered
0.0%Died or euthanised
31 daysTypical onset
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How soon it started

Same day
3 4.3%
1–2 days
8 12%
3–7 days
4 5.8%
1–4 weeks
18 26%
Over a month
36 52%

How the animals did

Recovered
4 3.8%
Recovered with lasting effects
1 1.0%
Still unwell when reported
8 7.7%
Not known
91 88%

Problems reported at the same time

Itching
16 15%
Didn't work as expected
12 12%
Behaviour change
6 5.8%
Hair loss
4 3.8%
Drug dose omission
4 3.8%
Restlessness or agitation
4 3.8%
Vomiting
3 2.9%
Underdose
3 2.9%

Age of the animals

Under 1 year
10
1–3 years
15
4–7 years
18
8–11 years
11
12+ years
10

About this medicine

Imidacloprid kills fleas (spot-on or collar).

Questions owners ask

Can Imidacloprid cause didn't stop fleas in cats?
104 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 31 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 fleas with similar medicines

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