Loose stool after Imidacloprid + Moxidectin (Advantage Multi) in cats

The FDA has received 25 reports of loose stool in cats after Imidacloprid + Moxidectin. That is 0.3% of all reports for this medicine, compared with 0.5% across reports for all cat medicines, so it is reported less often than average with this medicine.

25Reports
76%Marked serious
40%Recovered
8.0%Died or euthanised
2 daysTypical onset
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How soon it started

Same day
4 24%
1–2 days
6 35%
3–7 days
4 24%
1–4 weeks
2 12%
Over a month
1 5.9%

How the animals did

Recovered
10 40%
Died
1 4.0%
Euthanised
1 4.0%
Not known
13 52%

Problems reported at the same time

11 44%
Abnormal stool colouration
3 12%
3 12%
Blood in faeces
3 12%
3 12%

Age of the animals

Under 1 year
11
1–3 years
3
4–7 years
3
8–11 years
3
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 loose stool in cats?
25 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 2 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).

Loose stool with similar medicines

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