Monocytosis after Robenacoxib (Onsior) in cats

The FDA has received 40 reports of monocytosis in cats after Robenacoxib. That is 1.2% of all reports for this medicine, compared with 0.3% across reports for all cat medicines, so it is reported unusually often with this medicine.

40Reports

78%Marked serious

23%Recovered

33%Died or euthanised

2 daysTypical onset

How soon it started

Same day

12 32%

1–2 days

13 34%

3–7 days

4 11%

1–4 weeks

7 18%

Over a month

2 5.3%

How the animals did

Recovered

9 23%

Still unwell when reported

12 30%

Died

4 10%

Euthanised

9 23%

Not known

6 15%

Problems reported at the same time

27 68%

24 60%

21 53%

21 53%

19 48%

16 40%

15 38%

15 38%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Robenacoxib relieves pain and inflammation (short courses).

Products with this ingredient include Onsior. The FDA hides brand names in its public data, so these reports cover every product with the same active ingredients.

NSAIDs can affect the stomach, liver and kidneys. Vets usually recommend blood tests before and during long-term use.

Questions owners ask

Can Robenacoxib cause monocytosis in cats?: 40 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 2 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).

Monocytosis with similar medicines

Monocytosis after Meloxicam (Metacam) 29 reports · 0.8% of its reports

All reported side effects of Robenacoxib in cats · Medicines most reported with monocytosis