Dilated pupils after Mirtazapine (Mirataz) in cats

The FDA has received 52 reports of dilated pupils in cats after Mirtazapine. That is 2.8% of all reports for this medicine, compared with 1.4% across reports for all cat medicines, so it is reported unusually often with this medicine.

52Reports

62%Marked serious

23%Recovered

27%Died or euthanised

1 daysTypical onset

How soon it started

Same day

18 35%

1–2 days

11 22%

3–7 days

6 12%

1–4 weeks

6 12%

Over a month

10 20%

How the animals did

Recovered

12 23%

Still unwell when reported

14 27%

Died

10 19%

Euthanised

4 7.7%

Not known

12 23%

Problems reported at the same time

Loss of appetite

23 44%

Behaviour change

14 27%

Death

13 25%

Restlessness or agitation

13 25%

12 23%

11 21%

9 17%

9 17%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Mirtazapine stimulates appetite (cats: ointment applied to the ear).

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

Questions owners ask

Can Mirtazapine cause dilated pupils in cats?: 52 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 1 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).

Dilated pupils with similar medicines

Dilated pupils after Maropitant (Cerenia) 168 reports · 4.4% of its reports

All reported side effects of Mirtazapine in cats · Medicines most reported with dilated pupils