Blood problems after Flumethrin + Imidacloprid (Seresto) in dogs

The FDA has received 28 reports of blood problems in dogs after Flumethrin + Imidacloprid. That is 1.2% of all reports for this medicine, compared with 1.8% across reports for all dog medicines.

28Reports

86%Marked serious

7.1%Recovered

32%Died or euthanised

55 daysTypical onset

How soon it started

Same day

1 5.6%

1–2 days

1 5.6%

3–7 days

1 5.6%

1–4 weeks

5 28%

Over a month

10 56%

How the animals did

Recovered

2 7.1%

Still unwell when reported

6 21%

Died

4 14%

Euthanised

5 18%

Not known

11 39%

Problems reported at the same time

13 46%

13 46%

9 32%

8 29%

8 29%

7 25%

7 25%

7 25%

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).

Products with this combination include Seresto. The FDA hides brand names in its public data, so these reports cover every product with the same active ingredients.

Questions owners ask

Can Flumethrin + Imidacloprid cause blood problems in dogs?: 28 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).

Blood problems with similar medicines

Blood problems after Spinosad (Comfortis) 364 reports · 0.6% of its reports
Blood problems after Lufenuron + Milbemycin Oxime (Sentinel) 184 reports · 0.7% of its reports
Blood problems after Imidacloprid + Moxidectin (Advantage Multi) 88 reports · 0.7% of its reports
Blood problems after Nitenpyram (Capstar) 54 reports · 0.5% of its reports
Blood problems after Lufenuron + Milbemycin Oxime + Praziquantel (Sentinel Spectrum) 49 reports · 0.5% of its reports
Blood problems after Fipronil + S-methoprene (Frontline Plus) 23 reports · 0.8% of its reports
Blood problems after Fipronil 20 reports · 1.4% of its reports
Blood problems after Lufenuron 27 reports · 2.7% of its reports

All reported side effects of Flumethrin + Imidacloprid in dogs · Medicines most reported with blood problems