Didn't stop fleas after Imidacloprid + Moxidectin (Advantage Multi) in cats

1,073 reports to the FDA describe didn't stop fleas in cats given Imidacloprid + Moxidectin. That is 13% of all reports for this medicine, compared with 8.4% across reports for all cat medicines, so it is reported unusually often with this medicine.

1,073Reports

21%Marked serious

8.0%Recovered

0.9%Died or euthanised

14 daysTypical onset

How soon it started

Same day

37 5.7%

1–2 days

100 15%

3–7 days

78 12%

1–4 weeks

314 49%

Over a month

117 18%

How the animals did

Recovered

85 7.9%

Recovered with lasting effects

1 0.1%

Still unwell when reported

18 1.7%

Died

6 0.6%

Euthanised

4 0.4%

Not known

959 89%

Problems reported at the same time

Itching

303 28%

Hair loss

51 4.8%

Drug dose administration interval too short

44 4.1%

Behaviour change

41 3.8%

Drug dose administration interval too long

39 3.6%

Overdose

37 3.4%

Underdose

32 3.0%

Skin rash or irritation

31 2.9%

Age of the animals

Under 1 year

119

1–3 years

194

4–7 years

160

8–11 years

145

12+ years

139

About this medicine

Imidacloprid kills fleas (spot-on or collar). Moxidectin prevents heartworm disease (monthly topical, or a 6- or 12-month injection for dogs).

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

Questions owners ask

Can Imidacloprid + Moxidectin cause didn't stop fleas in cats?: 1,073 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 14 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 stop fleas with similar medicines

Didn't stop fleas after Spinosad (Comfortis) 1,841 reports · 16% of its reports
Didn't stop fleas after Nitenpyram (Capstar) 2,325 reports · 27% of its reports
Didn't stop fleas after Lufenuron 89 reports · 8.0% of its reports
Didn't stop fleas after Flumethrin + Imidacloprid (Seresto) 255 reports · 38% of its reports
Didn't stop fleas after Imidacloprid + Pyriproxyfen 282 reports · 43% of its reports
Didn't stop fleas after Fipronil 190 reports · 38% of its reports
Didn't stop fleas after Fipronil + S-methoprene (Frontline Plus) 134 reports · 37% of its reports
Didn't stop fleas after Imidacloprid 104 reports · 41% of its reports

All reported side effects of Imidacloprid + Moxidectin in cats · Medicines most reported with didn't stop fleas