Disorientation after Levothyroxine in dogs

61 reports to the FDA describe disorientation in dogs given Levothyroxine. That is 2.0% of all reports for this medicine, compared with 1.0% across reports for all dog medicines, so it is reported unusually often with this medicine.

61Reports

46%Marked serious

43%Recovered

9.8%Died or euthanised

18 daysTypical onset

How soon it started

Same day

8 23%

1–2 days

4 11%

3–7 days

3 8.6%

1–4 weeks

6 17%

Over a month

14 40%

How the animals did

Recovered

21 34%

Recovered with lasting effects

5 8.2%

Still unwell when reported

14 23%

Died

1 1.6%

Euthanised

5 8.2%

Not known

15 25%

Problems reported at the same time

22 36%

14 23%

14 23%

13 21%

12 20%

12 20%

10 16%

8 13%

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 disorientation in dogs?: 61 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 18 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).

Disorientation with similar medicines

Disorientation after Trilostane (Vetoryl) 167 reports · 1.4% of its reports
Disorientation after Insulin 137 reports · 1.9% of its reports
Disorientation after Phenylpropanolamine (Proin) 76 reports · 1.8% of its reports

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