Swelling after Flumethrin + Imidacloprid (Seresto) in dogs

The FDA has received 47 reports of swelling in dogs after Flumethrin + Imidacloprid. That is 2.1% of all reports for this medicine, compared with 2.8% across reports for all dog medicines.

47Reports

51%Marked serious

38%Recovered

11%Died or euthanised

16 daysTypical onset

How soon it started

Same day

9 23%

1–2 days

3 7.7%

3–7 days

5 13%

1–4 weeks

7 18%

Over a month

15 38%

How the animals did

Recovered

18 38%

Still unwell when reported

11 23%

Died

3 6.4%

Euthanised

2 4.3%

Not known

13 28%

Problems reported at the same time

14 30%

12 26%

11 23%

10 21%

8 17%

7 15%

7 15%

5 11%

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 swelling in dogs?: 47 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 16 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).

Swelling with similar medicines

Swelling after Spinosad (Comfortis) 399 reports · 0.7% of its reports
Swelling after Lufenuron + Milbemycin Oxime (Sentinel) 219 reports · 0.8% of its reports
Swelling after Imidacloprid + Moxidectin (Advantage Multi) 218 reports · 1.7% of its reports
Swelling after Nitenpyram (Capstar) 127 reports · 1.2% of its reports
Swelling after Lufenuron + Milbemycin Oxime + Praziquantel (Sentinel Spectrum) 70 reports · 0.7% of its reports
Swelling after Fipronil + S-methoprene (Frontline Plus) 42 reports · 1.4% of its reports
Swelling after Fipronil 20 reports · 1.4% of its reports
Swelling after Lufenuron 44 reports · 4.3% of its reports

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