Didn't prevent heartworm after Fipronil in dogs

30 reports to the FDA describe didn't prevent heartworm in dogs given Fipronil. That is 2.1% of all reports for this medicine, compared with 13% across reports for all dog medicines, so it is reported less often than average with this medicine.

30Reports

13%Marked serious

0.0%Recovered

0.0%Died or euthanised

353 daysTypical onset

How soon it started

Same day

0 0.0%

1–2 days

0 0.0%

3–7 days

0 0.0%

1–4 weeks

0 0.0%

Over a month

12 100%

How the animals did

Still unwell when reported

8 27%

Not known

22 73%

Problems reported at the same time

Didn't work as expected

3 10%

Drug dose omission

2 6.7%

Cardiac enlargement

1 3.3%

Pulmonary disorder

1 3.3%

Liver problems

1 3.3%

Musculoskeletal disorder

1 3.3%

Itching

1 3.3%

Scale

1 3.3%

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 prevent heartworm in dogs?: 30 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 353 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 prevent heartworm with similar medicines

Didn't prevent heartworm after Spinosad (Comfortis) 99 reports · 0.2% of its reports
Didn't prevent heartworm after Lufenuron + Milbemycin Oxime (Sentinel) 7,458 reports · 29% of its reports
Didn't prevent heartworm after Imidacloprid + Moxidectin (Advantage Multi) 1,665 reports · 13% of its reports
Didn't prevent heartworm after Nitenpyram (Capstar) 30 reports · 0.3% of its reports
Didn't prevent heartworm after Lufenuron + Milbemycin Oxime + Praziquantel (Sentinel Spectrum) 2,544 reports · 26% of its reports
Didn't prevent heartworm after Fipronil + S-methoprene (Frontline Plus) 31 reports · 1.0% of its reports
Didn't prevent heartworm after Flumethrin + Imidacloprid (Seresto) 62 reports · 2.7% of its reports
Didn't prevent heartworm after Imidacloprid + Permethrin 20 reports · 4.3% of its reports

All reported side effects of Fipronil in dogs · Medicines most reported with didn't prevent heartworm