Diarrhea after Imidacloprid + Moxidectin (Advantage Multi) in cats

The FDA has received 213 reports of diarrhea in cats after Imidacloprid + Moxidectin. That is 2.6% of all reports for this medicine, compared with 5.1% across reports for all cat medicines, so it is reported less often than average with this medicine.

213Reports
68%Marked serious
36%Recovered
8.9%Died or euthanised
1 daysTypical onset
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How soon it started

Same day
58 40%
1–2 days
47 32%
3–7 days
12 8.2%
1–4 weeks
16 11%
Over a month
13 8.9%

How the animals did

Recovered
76 36%
Still unwell when reported
16 7.5%
Died
14 6.6%
Euthanised
5 2.3%
Not known
102 48%

Problems reported at the same time

103 48%
69 32%
24 11%
18 8.5%
17 8.0%

Age of the animals

Under 1 year
60
1–3 years
36
4–7 years
35
8–11 years
41
12+ years
33

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 diarrhea in cats?
213 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 1 day 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).

Diarrhea with similar medicines

All reported side effects of Imidacloprid + Moxidectin in cats · Medicines most reported with diarrhea