Didn't stop fleas after Imidacloprid + Permethrin in dogs

The FDA has received 92 reports of didn't stop fleas in dogs after Imidacloprid + Permethrin. That is 20% 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.

92Reports

9.8%Marked serious

6.5%Recovered

4.3%Died or euthanised

55 daysTypical onset

How soon it started

Same day

9 13%

1–2 days

5 7.1%

3–7 days

2 2.9%

1–4 weeks

14 20%

Over a month

40 57%

How the animals did

Recovered

3 3.3%

Recovered with lasting effects

3 3.3%

Still unwell when reported

14 15%

Died

3 3.3%

Euthanised

1 1.1%

Not known

68 74%

Problems reported at the same time

Didn't work as expected

23 25%

Itching

15 16%

Vomiting

4 4.3%

Death

4 4.3%

Overdose

3 3.3%

Skin rash or irritation

2 2.2%

Tremors

2 2.2%

Reluctant to move

2 2.2%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Imidacloprid kills fleas (spot-on or collar).

Questions owners ask

Can Imidacloprid + Permethrin cause didn't stop fleas in dogs?: 92 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 55 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 Flumethrin + Imidacloprid (Seresto) 882 reports · 39% 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

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