Medication error after Levothyroxine in dogs

The FDA has received 35 reports of medication error in dogs after Levothyroxine. That is 1.2% of all reports for this medicine, compared with 0.6% across reports for all dog medicines, so it is reported unusually often with this medicine.

35Reports

63%Marked serious

23%Recovered

17%Died or euthanised

121 daysTypical onset

How soon it started

Same day

0 0.0%

1–2 days

2 9.1%

3–7 days

1 4.5%

1–4 weeks

1 4.5%

Over a month

18 82%

How the animals did

Recovered

8 23%

Still unwell when reported

18 51%

Died

2 5.7%

Euthanised

4 11%

Not known

3 8.6%

Problems reported at the same time

Didn't work as expected

10 29%

7 20%

6 17%

5 14%

5 14%

4 11%

4 11%

4 11%

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 medication error in dogs?: 35 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 121 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).

Medication error with similar medicines

Medication error after Trilostane (Vetoryl) 83 reports · 0.7% of its reports
Medication error after Insulin 209 reports · 2.8% of its reports
Medication error after Phenylpropanolamine (Proin) 30 reports · 0.7% of its reports

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