Didn't work as expected after Cetirizine in dogs

The FDA has received 133 reports of didn't work as expected in dogs after Cetirizine. That is 20% of all reports for this medicine, compared with 13% across reports for all dog medicines, so it is reported unusually often with this medicine.

133Reports
22%Marked serious
5.3%Recovered
1.5%Died or euthanised
72 daysTypical onset
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How soon it started

Same day
10 14%
1–2 days
1 1.4%
3–7 days
5 6.8%
1–4 weeks
9 12%
Over a month
48 66%

How the animals did

Recovered
5 3.8%
Recovered with lasting effects
2 1.5%
Still unwell when reported
76 57%
Died
1 0.8%
Euthanised
1 0.8%
Not known
48 36%

Problems reported at the same time

12 9.0%
10 7.5%
9 6.8%
Didn't stop fleas
8 6.0%
Underdose
8 6.0%
6 4.5%

Age of the animals

Under 1 year
1
1–3 years
25
4–7 years
51
8–11 years
34
12+ years
21

About this medicine

Type: medicine.

Questions owners ask

Can Cetirizine cause didn't work as expected in dogs?
133 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 72 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).

Didn't work as expected with similar medicines

All reported side effects of Cetirizine in dogs · Medicines most reported with didn't work as expected