Medication error after Methimazole in cats

The FDA has received 27 reports of medication error in cats after Methimazole. That is 1.5% of all reports for this medicine, compared with 0.6% across reports for all cat medicines, so it is reported unusually often with this medicine.

27Reports

59%Marked serious

7.4%Recovered

11%Died or euthanised

20 daysTypical onset

How soon it started

Same day

7 29%

1–2 days

3 13%

3–7 days

1 4.2%

1–4 weeks

4 17%

Over a month

9 38%

How the animals did

Recovered

2 7.4%

Still unwell when reported

12 44%

Euthanised

3 11%

Not known

10 37%

Problems reported at the same time

Loss of appetite

8 30%

Lethargy

6 22%

Vomiting

6 22%

Underdose

5 19%

4 15%

4 15%

4 15%

4 15%

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 medication error in cats?: 27 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 20 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).

Medication error with similar medicines

Medication error after Insulin 55 reports · 1.5% of its reports

All reported side effects of Methimazole in cats · Medicines most reported with medication error