Lethargy after Lufenuron in cats

The FDA has received 236 reports of lethargy in cats after Lufenuron. That is 21% of all reports for this medicine, compared with 14% across reports for all cat medicines, so it is reported unusually often with this medicine.

236Reports

7.6%Marked serious

5.9%Recovered

12%Died or euthanised

3 daysTypical onset

How soon it started

Same day

6 29%

1–2 days

4 19%

3–7 days

6 29%

1–4 weeks

2 9.5%

Over a month

3 14%

How the animals did

Recovered

14 5.9%

Still unwell when reported

8 3.4%

Died

26 11%

Euthanised

3 1.3%

Not known

185 78%

Problems reported at the same time

Loss of appetite

134 57%

Vomiting

70 30%

Fever

50 21%

Injection site reaction

32 14%

29 12%

28 12%

27 11%

19 8.1%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Lufenuron stops flea eggs from developing.

Questions owners ask

Can Lufenuron cause lethargy in cats?: 236 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 3 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) 1,080 reports · 9.3% of its reports
Lethargy after Nitenpyram (Capstar) 926 reports · 11% of its reports
Lethargy after Imidacloprid + Moxidectin (Advantage Multi) 1,394 reports · 17% of its reports
Lethargy after Flumethrin + Imidacloprid (Seresto) 72 reports · 11% of its reports
Lethargy after Imidacloprid + Pyriproxyfen 73 reports · 11% of its reports
Lethargy after Fipronil 62 reports · 12% of its reports
Lethargy after Fipronil + S-methoprene (Frontline Plus) 51 reports · 14% of its reports
Lethargy after Imidacloprid 33 reports · 13% of its reports

All reported side effects of Lufenuron in cats · Medicines most reported with lethargy