Behaviour change after Amoxicillin in cats

The FDA has received 27 reports of behaviour change in cats after Amoxicillin. That is 5.3% of all reports for this medicine, compared with 5.4% across reports for all cat medicines.

27Reports

56%Marked serious

26%Recovered

7.4%Died or euthanised

2 daysTypical onset

How soon it started

Same day

7 35%

1–2 days

4 20%

3–7 days

2 10%

1–4 weeks

3 15%

Over a month

4 20%

How the animals did

Recovered

7 26%

Still unwell when reported

6 22%

Died

1 3.7%

Euthanised

1 3.7%

Not known

12 44%

Problems reported at the same time

Loss of appetite

9 33%

Lethargy

8 30%

Vocalising

6 22%

Itching

6 22%

Drooling

5 19%

Vomiting

5 19%

Restlessness or agitation

5 19%

Wobbliness (ataxia)

4 15%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Amoxicillin treats bacterial infections.

Questions owners ask

Can Amoxicillin cause behaviour change in cats?: 27 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).

Behaviour change with similar medicines

Behaviour change after Cefovecin (Convenia) 603 reports · 6.9% of its reports
Behaviour change after Amoxicillin + Clavulanate (Clavamox) 96 reports · 4.0% of its reports
Behaviour change after Enrofloxacin (Baytril) 132 reports · 8.4% of its reports
Behaviour change after Metronidazole 31 reports · 7.9% of its reports

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