Didn't stop fleas after Flumethrin + Imidacloprid (Seresto) in dogs

The FDA has received 882 reports of didn't stop fleas in dogs after Flumethrin + Imidacloprid. That is 39% 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.

882Reports

9.6%Marked serious

2.9%Recovered

1.5%Died or euthanised

57 daysTypical onset

How soon it started

Same day

41 5.8%

1–2 days

55 7.8%

3–7 days

31 4.4%

1–4 weeks

118 17%

Over a month

460 65%

How the animals did

Recovered

22 2.5%

Recovered with lasting effects

4 0.5%

Still unwell when reported

138 16%

Died

11 1.2%

Euthanised

2 0.2%

Not known

705 80%

Problems reported at the same time

Itching

337 38%

Hair loss

43 4.9%

Skin rash or irritation

35 4.0%

Behaviour change

31 3.5%

Vomiting

22 2.5%

Lethargy

22 2.5%

Didn't work as expected

19 2.2%

Application site reaction

18 2.0%

Age of the animals

Under 1 year

1–3 years

152

4–7 years

179

8–11 years

187

12+ years

121

About this medicine

Imidacloprid kills fleas (spot-on or collar).

Products with this combination include Seresto. The FDA hides brand names in its public data, so these reports cover every product with the same active ingredients.

Questions owners ask

Can Flumethrin + Imidacloprid cause didn't stop fleas in dogs?: 882 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 57 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

Didn't stop fleas after Spinosad (Comfortis) 13,280 reports · 23% of its reports
Didn't stop fleas after Lufenuron + Milbemycin Oxime (Sentinel) 977 reports · 3.8% of its reports
Didn't stop fleas after Imidacloprid + Moxidectin (Advantage Multi) 1,444 reports · 11% of its reports
Didn't stop fleas after Nitenpyram (Capstar) 6,142 reports · 57% of its reports
Didn't stop fleas after Lufenuron + Milbemycin Oxime + Praziquantel (Sentinel Spectrum) 498 reports · 5.0% of its reports
Didn't stop fleas after Fipronil + S-methoprene (Frontline Plus) 576 reports · 19% of its reports
Didn't stop fleas after Imidacloprid 1,054 reports · 55% of its reports
Didn't stop fleas after Fipronil 394 reports · 28% of its reports
Didn't stop fleas after Lufenuron 44 reports · 4.3% of its reports
Didn't stop fleas after Imidacloprid + Permethrin + Pyriproxyfen 219 reports · 30% of its reports

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