Weight gain after Mirtazapine (Mirataz) in cats

The FDA has received 22 reports of weight gain in cats after Mirtazapine. That is 1.2% of all reports for this medicine, compared with 0.4% across reports for all cat medicines, so it is reported unusually often with this medicine.

22Reports

55%Marked serious

4.5%Recovered

18%Died or euthanised

14 daysTypical onset

How soon it started

Same day

2 11%

1–2 days

1 5.6%

3–7 days

4 22%

1–4 weeks

5 28%

Over a month

6 33%

How the animals did

Recovered

1 4.5%

Still unwell when reported

10 45%

Euthanised

4 18%

Not known

7 32%

Problems reported at the same time

9 41%

9 41%

8 36%

5 23%

5 23%

5 23%

Glucosuria

5 23%

Blood problems

5 23%

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 weight gain in cats?: 22 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 14 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).

Weight gain with similar medicines

Weight gain after Maropitant (Cerenia) 23 reports · 0.6% of its reports

All reported side effects of Mirtazapine in cats · Medicines most reported with weight gain