Death after Ivermectin (Heartgard) in cats

100 reports to the FDA describe death in cats given Ivermectin. That is 10% of all reports for this medicine, compared with 8.9% across reports for all cat medicines.

100Reports
18%Marked serious
0.0%Recovered
99%Died or euthanised
2 daysTypical onset
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How soon it started

Same day
3 23%
1–2 days
4 31%
3–7 days
2 15%
1–4 weeks
3 23%
Over a month
1 7.7%

How the animals did

Died
93 93%
Euthanised
6 6.0%
Not known
1 1.0%

Problems reported at the same time

Age of the animals

Under 1 year
33
1–3 years
18
4–7 years
16
8–11 years
9
12+ years
6

About this medicine

Ivermectin prevents heartworm disease (monthly).

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

Some herding breeds (for example Collies) carry the MDR1 gene variant and can be more sensitive to this drug class at high doses.

Questions owners ask

Can Ivermectin cause death in cats?
100 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).

Death with similar medicines

All reported side effects of Ivermectin in cats · Medicines most reported with death