Lethargy after Imidacloprid + Pyriproxyfen in dogs

26 reports to the FDA describe lethargy in dogs given Imidacloprid + Pyriproxyfen. That is 9.7% of all reports for this medicine, compared with 11% across reports for all dog medicines.

26Reports

58%Marked serious

35%Recovered

3.8%Died or euthanised

25 daysTypical onset

How soon it started

Same day

3 17%

1–2 days

3 17%

3–7 days

2 11%

1–4 weeks

6 33%

Over a month

4 22%

How the animals did

Recovered

9 35%

Still unwell when reported

3 12%

Euthanised

1 3.8%

Not known

13 50%

Problems reported at the same time

Loss of appetite

13 50%

Vomiting

12 46%

Diarrhea

10 38%

Behaviour change

6 23%

Vocalising

5 19%

Itching

5 19%

Seizures

2 7.7%

Breathing problems

2 7.7%

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).

Questions owners ask

Can Imidacloprid + Pyriproxyfen cause lethargy in dogs?: 26 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 25 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).

Lethargy with similar medicines

Lethargy after Spinosad (Comfortis) 7,303 reports · 13% of its reports
Lethargy after Lufenuron + Milbemycin Oxime (Sentinel) 2,341 reports · 9.0% of its reports
Lethargy after Imidacloprid + Moxidectin (Advantage Multi) 2,000 reports · 15% of its reports
Lethargy after Nitenpyram (Capstar) 1,204 reports · 11% of its reports
Lethargy after Lufenuron + Milbemycin Oxime + Praziquantel (Sentinel Spectrum) 666 reports · 6.7% of its reports
Lethargy after Fipronil + S-methoprene (Frontline Plus) 447 reports · 15% of its reports
Lethargy after Flumethrin + Imidacloprid (Seresto) 250 reports · 11% of its reports
Lethargy after Imidacloprid 196 reports · 10% of its reports
Lethargy after Fipronil 185 reports · 13% of its reports
Lethargy after Lufenuron 205 reports · 20% of its reports

All reported side effects of Imidacloprid + Pyriproxyfen in dogs · Medicines most reported with lethargy