Didn't stop fleas after Cyphenothrin + Fipronil in dogs

38 reports to the FDA describe didn't stop fleas in dogs given Cyphenothrin + Fipronil. That is 13% of all reports for this medicine, compared with 6.2% across reports for all dog medicines, so it is reported unusually often with this medicine.

38Reports
11%Marked serious
2.6%Recovered
0.0%Died or euthanised
–Typical onset
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How the animals did

Recovered
1 2.6%
Still unwell when reported
9 24%
Not known
28 74%

Problems reported at the same time

Didn't work as expected
4 11%
Itching
4 11%
Lethargy
2 5.3%
Hair shedding
1 2.6%
Vocalising
1 2.6%
Fever
1 2.6%
Breathing problems
1 2.6%
Unable to rise
1 2.6%

Age of the animals

Under 1 year
6
1–3 years
10
4–7 years
9
8–11 years
5
12+ years
4

About this medicine

Fipronil kills fleas and ticks (spot-on).

Questions owners ask

Can Cyphenothrin + Fipronil cause didn't stop fleas in dogs?
38 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.
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 Cyphenothrin + Fipronil in dogs · Medicines most reported with didn't stop fleas