Didn't work as expected after Vitamin B12 in cats

The FDA has received 57 reports of didn't work as expected in cats after Vitamin B12. That is 15% of all reports for this medicine, compared with 8.7% across reports for all cat medicines, so it is reported unusually often with this medicine.

57Reports
40%Marked serious
1.8%Recovered
14%Died or euthanised
21 daysTypical onset
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How soon it started

Same day
7 15%
1–2 days
1 2.2%
3–7 days
3 6.5%
1–4 weeks
15 33%
Over a month
20 43%

How the animals did

Recovered
1 1.8%
Still unwell when reported
28 49%
Died
2 3.5%
Euthanised
6 11%
Not known
20 35%

Problems reported at the same time

Age of the animals

Under 1 year
3
1–3 years
2
4–7 years
2
8–11 years
5
12+ years
41

About this medicine

Type: medicine.

Questions owners ask

Can Vitamin B12 cause didn't work as expected in cats?
57 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 21 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 Vitamin B12 in cats · Medicines most reported with didn't work as expected