Wobbliness (ataxia) after Methimazole in cats

89 reports to the FDA describe wobbliness (ataxia) in cats given Methimazole. That is 5.0% of all reports for this medicine, compared with 4.7% across reports for all cat medicines.

89Reports

64%Marked serious

26%Recovered

24%Died or euthanised

11 daysTypical onset

How soon it started

Same day

14 23%

1–2 days

6 9.8%

3–7 days

5 8.2%

1–4 weeks

11 18%

Over a month

25 41%

How the animals did

Recovered

22 25%

Recovered with lasting effects

1 1.1%

Still unwell when reported

32 36%

Died

5 5.6%

Euthanised

16 18%

Not known

13 15%

Problems reported at the same time

25 28%

22 25%

21 24%

14 16%

12 13%

11 12%

11 12%

10 11%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Methimazole treats an overactive thyroid in cats.

Questions owners ask

Can Methimazole cause wobbliness (ataxia) in cats?: 89 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 11 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).

Wobbliness (ataxia) with similar medicines

Wobbliness (ataxia) after Velagliflozin (Senvelgo) 40 reports · 0.8% of its reports
Wobbliness (ataxia) after Bexagliflozin (Bexacat) 33 reports · 0.8% of its reports
Wobbliness (ataxia) after Insulin 115 reports · 3.1% of its reports

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