Tremors after Levothyroxine in dogs

132 reports to the FDA describe tremors in dogs given Levothyroxine. That is 4.4% of all reports for this medicine, compared with 3.4% across reports for all dog medicines.

132Reports

62%Marked serious

33%Recovered

13%Died or euthanised

19 daysTypical onset

How soon it started

Same day

19 20%

1–2 days

10 11%

3–7 days

9 9.6%

1–4 weeks

14 15%

Over a month

42 45%

How the animals did

Recovered

41 31%

Recovered with lasting effects

3 2.3%

Still unwell when reported

43 33%

Died

7 5.3%

Euthanised

10 7.6%

Not known

28 21%

Problems reported at the same time

40 30%

34 26%

31 23%

24 18%

24 18%

22 17%

19 14%

18 14%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Levothyroxine treats an underactive thyroid.

Questions owners ask

Can Levothyroxine cause tremors in dogs?: 132 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 19 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).

Tremors with similar medicines

Tremors after Trilostane (Vetoryl) 751 reports · 6.3% of its reports
Tremors after Insulin 191 reports · 2.6% of its reports
Tremors after Phenylpropanolamine (Proin) 166 reports · 4.0% of its reports

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