Behaviour change after Naloxone in cats

The FDA has received 26 reports of behaviour change in cats after Naloxone. That is 27% of all reports for this medicine, compared with 5.4% across reports for all cat medicines, so it is reported unusually often with this medicine.

26Reports
85%Marked serious
27%Recovered
31%Died or euthanised
Same dayTypical onset
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How soon it started

Same day
16 62%
1–2 days
5 19%
3–7 days
4 15%
1–4 weeks
0 0.0%
Over a month
1 3.8%

How the animals did

Recovered
7 27%
Still unwell when reported
7 27%
Died
2 7.7%
Euthanised
6 23%
Not known
4 15%

Problems reported at the same time

10 38%
Eye or vision problems
9 35%
Restlessness or agitation
9 35%
Dysphoria
8 31%
Seizures
7 27%
7 27%
Unable to stand
7 27%

Age of the animals

Under 1 year
4
1–3 years
4
4–7 years
5
8–11 years
3
12+ years
10

About this medicine

Type: medicine.

Questions owners ask

Can Naloxone cause behaviour change in cats?
26 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 the same 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).

Behaviour change with similar medicines

All reported side effects of Naloxone in cats · Medicines most reported with behaviour change