Wobbliness (ataxia) after Ivermectin (Heartgard) in cats

227 reports to the FDA describe wobbliness (ataxia) in cats given Ivermectin. That is 24% of all reports for this medicine, compared with 4.7% across reports for all cat medicines, so it is reported unusually often with this medicine.

227Reports

11%Marked serious

8.8%Recovered

13%Died or euthanised

1 daysTypical onset

How soon it started

Same day

13 35%

1–2 days

15 41%

3–7 days

2 5.4%

1–4 weeks

3 8.1%

Over a month

4 11%

How the animals did

Recovered

14 6.2%

Recovered with lasting effects

6 2.6%

Still unwell when reported

7 3.1%

Died

30 13%

Not known

170 75%

Problems reported at the same time

Eye or vision problems

96 42%

57 25%

36 16%

29 13%

27 12%

26 11%

20 8.8%

Loss of consciousness

20 8.8%

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 wobbliness (ataxia) in cats?: 227 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).

Wobbliness (ataxia) with similar medicines

Wobbliness (ataxia) after Selamectin (Revolution) 812 reports · 3.7% of its reports
Wobbliness (ataxia) after Eprinomectin + Esafoxolaner + Praziquantel (NexGard Combo) 224 reports · 6.9% of its reports
Wobbliness (ataxia) after Eprinomectin + Praziquantel 29 reports · 5.0% of its reports
Wobbliness (ataxia) after Milbemycin Oxime (Interceptor) 54 reports · 13% of its reports
Wobbliness (ataxia) after Milbemycin Oxime + Spinosad (Trifexis) 25 reports · 8.3% of its reports

All reported side effects of Ivermectin in cats · Medicines most reported with wobbliness (ataxia)