Didn't prevent heartworm after Imidacloprid + Moxidectin (Advantage Multi) in dogs

1,665 reports to the FDA describe didn't prevent heartworm in dogs given Imidacloprid + Moxidectin. That is 13% of all reports for this medicine, compared with 13% across reports for all dog medicines.

1,665Reports

58%Marked serious

9.3%Recovered

0.9%Died or euthanised

104 daysTypical onset

How soon it started

Same day

12 1.9%

1–2 days

15 2.4%

3–7 days

35 5.6%

1–4 weeks

164 26%

Over a month

404 64%

How the animals did

Recovered

152 9.1%

Recovered with lasting effects

3 0.2%

Still unwell when reported

184 11%

Died

10 0.6%

Euthanised

5 0.3%

Not known

1,311 79%

Problems reported at the same time

Weight gain

87 5.2%

Cough

49 2.9%

Overdose

47 2.8%

Didn't work as expected

43 2.6%

43 2.6%

42 2.5%

37 2.2%

36 2.2%

Age of the animals

Under 1 year

1–3 years

915

4–7 years

405

8–11 years

195

12+ years

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 prevent heartworm in dogs?: 1,665 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 104 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 prevent heartworm with similar medicines

Didn't prevent heartworm after Spinosad (Comfortis) 99 reports · 0.2% of its reports
Didn't prevent heartworm after Lufenuron + Milbemycin Oxime (Sentinel) 7,458 reports · 29% of its reports
Didn't prevent heartworm after Nitenpyram (Capstar) 30 reports · 0.3% of its reports
Didn't prevent heartworm after Lufenuron + Milbemycin Oxime + Praziquantel (Sentinel Spectrum) 2,544 reports · 26% of its reports
Didn't prevent heartworm after Fipronil + S-methoprene (Frontline Plus) 31 reports · 1.0% of its reports
Didn't prevent heartworm after Flumethrin + Imidacloprid (Seresto) 62 reports · 2.7% of its reports
Didn't prevent heartworm after Fipronil 30 reports · 2.1% of its reports
Didn't prevent heartworm after Imidacloprid + Permethrin 20 reports · 4.3% of its reports

All reported side effects of Imidacloprid + Moxidectin in dogs · Medicines most reported with didn't prevent heartworm