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

77 reports to the FDA describe didn't stop worms in cats given Imidacloprid + Moxidectin. That is 0.9% of all reports for this medicine, compared with 1.8% across reports for all cat medicines, so it is reported less often than average with this medicine.

77Reports
52%Marked serious
17%Recovered
2.6%Died or euthanised
22 daysTypical onset
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How soon it started

Same day
2 3.6%
1–2 days
3 5.4%
3–7 days
7 13%
1–4 weeks
31 55%
Over a month
13 23%

How the animals did

Recovered
13 17%
Still unwell when reported
4 5.2%
Euthanised
2 2.6%
Not known
58 75%

Problems reported at the same time

Age of the animals

Under 1 year
25
1–3 years
15
4–7 years
16
8–11 years
5
12+ years
3

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 worms in cats?
77 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 22 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 worms with similar medicines

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