Pale mucous membrane after Methimazole in cats

31 reports to the FDA describe pale mucous membrane in cats given Methimazole. That is 1.7% 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.

31Reports

77%Marked serious

6.5%Recovered

42%Died or euthanised

42 daysTypical onset

How soon it started

Same day

1 3.8%

1–2 days

1 3.8%

3–7 days

1 3.8%

1–4 weeks

7 27%

Over a month

16 62%

How the animals did

Recovered

2 6.5%

Still unwell when reported

7 23%

Died

3 9.7%

Euthanised

10 32%

Not known

9 29%

Problems reported at the same time

18 58%

15 48%

15 48%

13 42%

10 32%

9 29%

8 26%

Decreased packed cell volume (pcv)

8 26%

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 pale mucous membrane in cats?: 31 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 42 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).

All reported side effects of Methimazole in cats · Medicines most reported with pale mucous membrane