Itching after Levothyroxine in dogs

248 reports to the FDA describe itching in dogs given Levothyroxine. That is 8.2% of all reports for this medicine, compared with 4.3% across reports for all dog medicines, so it is reported unusually often with this medicine.

248Reports

56%Marked serious

36%Recovered

2.4%Died or euthanised

15 daysTypical onset

How soon it started

Same day

16 8.3%

1–2 days

26 14%

3–7 days

35 18%

1–4 weeks

47 24%

Over a month

68 35%

How the animals did

Recovered

75 30%

Recovered with lasting effects

14 5.6%

Still unwell when reported

52 21%

Died

1 0.4%

Euthanised

5 2.0%

Not known

101 41%

Problems reported at the same time

Skin rash or irritation

51 21%

38 15%

34 14%

31 13%

27 11%

27 11%

25 10%

24 9.7%

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 itching in dogs?: 248 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 15 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).

Itching with similar medicines

Itching after Trilostane (Vetoryl) 254 reports · 2.1% of its reports
Itching after Insulin 182 reports · 2.5% of its reports
Itching after Phenylpropanolamine (Proin) 111 reports · 2.7% of its reports

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