Didn't stop worms after Fipronil in dogs

52 reports to the FDA describe didn't stop worms in dogs given Fipronil. That is 3.7% of all reports for this medicine, compared with 8.4% across reports for all dog medicines, so it is reported less often than average with this medicine.

52Reports

9.6%Marked serious

5.8%Recovered

1.9%Died or euthanised

106 daysTypical onset

How soon it started

Same day

1 4.5%

1–2 days

0 0.0%

3–7 days

0 0.0%

1–4 weeks

5 23%

Over a month

16 73%

How the animals did

Recovered

2 3.8%

Recovered with lasting effects

1 1.9%

Still unwell when reported

5 9.6%

Euthanised

1 1.9%

Not known

43 83%

Problems reported at the same time

Didn't work as expected

15 29%

5 9.6%

4 7.7%

4 7.7%

4 7.7%

3 5.8%

2 3.8%

2 3.8%

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 worms in dogs?: 52 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 106 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 worms with similar medicines

Didn't stop worms after Spinosad (Comfortis) 60 reports · 0.1% of its reports
Didn't stop worms after Lufenuron + Milbemycin Oxime (Sentinel) 4,911 reports · 19% of its reports
Didn't stop worms after Imidacloprid + Moxidectin (Advantage Multi) 821 reports · 6.3% of its reports
Didn't stop worms after Nitenpyram (Capstar) 28 reports · 0.3% of its reports
Didn't stop worms after Lufenuron + Milbemycin Oxime + Praziquantel (Sentinel Spectrum) 2,556 reports · 26% of its reports
Didn't stop worms after Fipronil + S-methoprene (Frontline Plus) 57 reports · 1.9% of its reports
Didn't stop worms after Flumethrin + Imidacloprid (Seresto) 80 reports · 3.5% of its reports
Didn't stop worms after Imidacloprid + Permethrin + Pyriproxyfen 30 reports · 4.1% of its reports
Didn't stop worms after Imidacloprid + Permethrin 20 reports · 4.3% of its reports

All reported side effects of Fipronil in dogs · Medicines most reported with didn't stop worms