Lethargy after Zonisamide in dogs

The FDA has received 56 reports of lethargy in dogs after Zonisamide. That is 18% of all reports for this medicine, compared with 11% across reports for all dog medicines, so it is reported unusually often with this medicine.

56Reports
59%Marked serious
25%Recovered
23%Died or euthanised
6 daysTypical onset
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How soon it started

Same day
6 19%
1–2 days
5 16%
3–7 days
6 19%
1–4 weeks
4 13%
Over a month
11 34%

How the animals did

Recovered
14 25%
Still unwell when reported
18 32%
Died
4 7.1%
Euthanised
9 16%
Not known
11 20%

Problems reported at the same time

Age of the animals

Under 1 year
0
1–3 years
8
4–7 years
20
8–11 years
18
12+ years
9

About this medicine

Type: medicine.

Questions owners ask

Can Zonisamide cause lethargy in dogs?
56 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 6 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 Zonisamide in dogs · Medicines most reported with lethargy