Vomiting after Methimazole in cats

The FDA has received 426 reports of vomiting in cats after Methimazole. That is 24% of all reports for this medicine, compared with 18% across reports for all cat medicines.

426Reports

44%Marked serious

38%Recovered

10%Died or euthanised

14 daysTypical onset

How soon it started

Same day

70 22%

1–2 days

33 10%

3–7 days

24 7.5%

1–4 weeks

89 28%

Over a month

104 33%

How the animals did

Recovered

157 37%

Recovered with lasting effects

7 1.6%

Still unwell when reported

91 21%

Died

21 4.9%

Euthanised

22 5.2%

Not known

128 30%

Problems reported at the same time

160 38%

107 25%

76 18%

49 12%

47 11%

41 9.6%

41 9.6%

32 7.5%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

337

About this medicine

Methimazole treats an overactive thyroid in cats.

Questions owners ask

Can Methimazole cause vomiting in cats?: 426 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 14 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).

Vomiting with similar medicines

Vomiting after Velagliflozin (Senvelgo) 690 reports · 14% of its reports
Vomiting after Bexagliflozin (Bexacat) 525 reports · 13% of its reports
Vomiting after Insulin 419 reports · 11% of its reports

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