Vomiting after Ivermectin (Heartgard) in cats

292 reports to the FDA describe vomiting in cats given Ivermectin. That is 30% of all reports for this medicine, compared with 18% across reports for all cat medicines, so it is reported unusually often with this medicine.

292Reports

30%Marked serious

43%Recovered

3.1%Died or euthanised

1 daysTypical onset

How soon it started

Same day

61 50%

1–2 days

17 14%

3–7 days

5 4.1%

1–4 weeks

5 4.1%

Over a month

34 28%

How the animals did

Recovered

126 43%

Recovered with lasting effects

1 0.3%

Still unwell when reported

3 1.0%

Died

9 3.1%

Not known

153 52%

Problems reported at the same time

38 13%

37 13%

23 7.9%

20 6.8%

Eye or vision problems

9 3.1%

Kidney problems

9 3.1%

Tremors

9 3.1%

Death

8 2.7%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

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 vomiting in cats?: 292 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).

Vomiting with similar medicines

Vomiting after Selamectin (Revolution) 2,379 reports · 11% of its reports
Vomiting after Eprinomectin + Esafoxolaner + Praziquantel (NexGard Combo) 445 reports · 14% of its reports
Vomiting after Eprinomectin + Praziquantel 99 reports · 17% of its reports
Vomiting after Milbemycin Oxime (Interceptor) 69 reports · 17% of its reports
Vomiting after Milbemycin Oxime + Spinosad (Trifexis) 142 reports · 47% of its reports
Vomiting after Ivermectin + Pyrantel (Heartgard Plus) 31 reports · 47% of its reports

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