Didn't stop fleas after Fipronil in dogs

394 reports to the FDA describe didn't stop fleas in dogs given Fipronil. That is 28% 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.

394Reports

7.4%Marked serious

8.1%Recovered

0.3%Died or euthanised

29 daysTypical onset

How soon it started

Same day

13 5.2%

1–2 days

20 8.0%

3–7 days

17 6.8%

1–4 weeks

80 32%

Over a month

119 48%

How the animals did

Recovered

18 4.6%

Recovered with lasting effects

14 3.6%

Still unwell when reported

73 19%

Euthanised

1 0.3%

Not known

288 73%

Problems reported at the same time

Didn't work as expected

61 15%

51 13%

12 3.0%

10 2.5%

9 2.3%

Skin rash or irritation

9 2.3%

Administration error

9 2.3%

Underdose

8 2.0%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Fipronil kills fleas and ticks (spot-on).

Questions owners ask

Can Fipronil cause didn't stop fleas in dogs?: 394 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 29 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 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 Fipronil in dogs · Medicines most reported with didn't stop fleas