Kidney problems after Methimazole in cats

160 reports to the FDA describe kidney problems in cats given Methimazole. That is 9.0% of all reports for this medicine, compared with 4.5% across reports for all cat medicines, so it is reported unusually often with this medicine.

160Reports

63%Marked serious

7.5%Recovered

21%Died or euthanised

36 daysTypical onset

How soon it started

Same day

17 15%

1–2 days

8 7.0%

3–7 days

5 4.4%

1–4 weeks

20 18%

Over a month

64 56%

How the animals did

Recovered

9 5.6%

Recovered with lasting effects

3 1.9%

Still unwell when reported

54 34%

Died

16 10%

Euthanised

18 11%

Not known

60 38%

Problems reported at the same time

69 43%

48 30%

48 30%

37 23%

33 21%

31 19%

26 16%

Elevated symmetrical dimethylarginine (sdma)

26 16%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

140

About this medicine

Methimazole treats an overactive thyroid in cats.

Questions owners ask

Can Methimazole cause kidney problems in cats?: 160 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 36 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).

Kidney problems with similar medicines

Kidney problems after Velagliflozin (Senvelgo) 445 reports · 9.3% of its reports
Kidney problems after Bexagliflozin (Bexacat) 420 reports · 10% of its reports
Kidney problems after Insulin 191 reports · 5.1% of its reports

All reported side effects of Methimazole in cats · Medicines most reported with kidney problems