Didn't work as expected after Fipronil in dogs

152 reports to the FDA describe didn't work as expected in dogs given Fipronil. That is 11% of all reports for this medicine, compared with 13% across reports for all dog medicines.

152Reports

11%Marked serious

11%Recovered

0.0%Died or euthanised

82 daysTypical onset

How soon it started

Same day

5 5.6%

1–2 days

6 6.7%

3–7 days

1 1.1%

1–4 weeks

20 22%

Over a month

58 64%

How the animals did

Recovered

10 6.6%

Recovered with lasting effects

6 3.9%

Still unwell when reported

33 22%

Not known

103 68%

Problems reported at the same time

61 40%

15 9.9%

9 5.9%

7 4.6%

5 3.3%

Didn't stop ticks

5 3.3%

Loose stool

4 2.6%

Weight gain

4 2.6%

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 work as expected in dogs?: 152 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 82 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 work as expected with similar medicines

Didn't work as expected after Spinosad (Comfortis) 1,731 reports · 3.0% of its reports
Didn't work as expected after Lufenuron + Milbemycin Oxime (Sentinel) 4,480 reports · 17% of its reports
Didn't work as expected after Imidacloprid + Moxidectin (Advantage Multi) 631 reports · 4.8% of its reports
Didn't work as expected after Nitenpyram (Capstar) 803 reports · 7.4% of its reports
Didn't work as expected after Lufenuron + Milbemycin Oxime + Praziquantel (Sentinel Spectrum) 1,429 reports · 14% of its reports
Didn't work as expected after Fipronil + S-methoprene (Frontline Plus) 243 reports · 8.2% of its reports
Didn't work as expected after Flumethrin + Imidacloprid (Seresto) 209 reports · 9.2% of its reports
Didn't work as expected after Imidacloprid 105 reports · 5.5% of its reports
Didn't work as expected after Imidacloprid + Permethrin + Pyriproxyfen 30 reports · 4.1% of its reports
Didn't work as expected after Imidacloprid + Permethrin 70 reports · 15% of its reports

All reported side effects of Fipronil in dogs · Medicines most reported with didn't work as expected