Lethargy after Azathioprine in dogs

The FDA has received 33 reports of lethargy in dogs after Azathioprine. That is 31% of all reports for this medicine, compared with 11% across reports for all dog medicines, so it is reported unusually often with this medicine.

33Reports
73%Marked serious
12%Recovered
42%Died or euthanised
3 daysTypical onset
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How soon it started

Same day
9 32%
1–2 days
5 18%
3–7 days
2 7.1%
1–4 weeks
5 18%
Over a month
7 25%

How the animals did

Recovered
4 12%
Still unwell when reported
11 33%
Died
8 24%
Euthanised
6 18%
Not known
4 12%

Problems reported at the same time

15 45%
14 42%
Leucocytosis
10 30%
Breathing problems
9 27%

Age of the animals

Under 1 year
0
1–3 years
7
4–7 years
14
8–11 years
11
12+ years
1

About this medicine

Type: medicine.

Questions owners ask

Can Azathioprine cause lethargy in dogs?
33 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 3 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).

Lethargy with similar medicines

All reported side effects of Azathioprine in dogs · Medicines most reported with lethargy