Vomiting after Levothyroxine in dogs

The FDA has received 801 reports of vomiting in dogs after Levothyroxine. That is 27% of all reports for this medicine, compared with 28% across reports for all dog medicines.

801Reports

38%Marked serious

61%Recovered

11%Died or euthanised

78 daysTypical onset

How soon it started

Same day

71 14%

1–2 days

35 7.1%

3–7 days

27 5.4%

1–4 weeks

59 12%

Over a month

304 61%

How the animals did

Recovered

464 58%

Recovered with lasting effects

22 2.7%

Still unwell when reported

110 14%

Died

32 4.0%

Euthanised

53 6.6%

Not known

120 15%

Problems reported at the same time

196 24%

175 22%

156 19%

97 12%

84 10%

59 7.4%

58 7.2%

54 6.7%

Age of the animals

Under 1 year

1–3 years

4–7 years

197

8–11 years

335

12+ years

229

About this medicine

Levothyroxine treats an underactive thyroid.

Questions owners ask

Can Levothyroxine cause vomiting in dogs?: 801 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 78 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 Trilostane (Vetoryl) 2,093 reports · 18% of its reports
Vomiting after Insulin 904 reports · 12% of its reports
Vomiting after Phenylpropanolamine (Proin) 1,365 reports · 33% of its reports

All reported side effects of Levothyroxine in dogs · Medicines most reported with vomiting