Accidental exposure after Levothyroxine in dogs

The FDA has received 20 reports of accidental exposure in dogs after Levothyroxine. That is 0.7% of all reports for this medicine, compared with 1.5% across reports for all dog medicines, so it is reported less often than average with this medicine.

20Reports

30%Marked serious

70%Recovered

0.0%Died or euthanised

1 daysTypical onset

How soon it started

Same day

7 50%

1–2 days

2 14%

3–7 days

0 0.0%

1–4 weeks

0 0.0%

Over a month

5 36%

How the animals did

Recovered

13 65%

Recovered with lasting effects

1 5.0%

Still unwell when reported

1 5.0%

Not known

5 25%

Problems reported at the same time

Overdose

9 45%

Lethargy

6 30%

No sign

5 25%

Loss of appetite

3 15%

Vomiting

3 15%

Restlessness or agitation

2 10%

Disorientation

2 10%

Liver problems

2 10%

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 accidental exposure in dogs?: 20 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 1 day 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).

Accidental exposure with similar medicines

Accidental exposure after Trilostane (Vetoryl) 33 reports · 0.3% of its reports
Accidental exposure after Insulin 21 reports · 0.3% of its reports
Accidental exposure after Phenylpropanolamine (Proin) 372 reports · 9.0% of its reports

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