Didn't stop worms after Metronidazole in dogs

The FDA has received 143 reports of didn't stop worms in dogs after Metronidazole. That is 4.6% of all reports for this medicine, compared with 8.4% across reports for all dog medicines, so it is reported less often than average with this medicine.

143Reports

38%Marked serious

9.1%Recovered

2.1%Died or euthanised

41 daysTypical onset

How soon it started

Same day

2 1.8%

1–2 days

1 0.9%

3–7 days

5 4.5%

1–4 weeks

35 32%

Over a month

67 61%

How the animals did

Recovered

12 8.4%

Recovered with lasting effects

1 0.7%

Still unwell when reported

38 27%

Died

2 1.4%

Euthanised

1 0.7%

Not known

89 62%

Problems reported at the same time

Diarrhea

49 34%

Didn't work as expected

34 24%

23 16%

18 13%

15 10%

14 9.8%

9 6.3%

9 6.3%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Metronidazole treats some bacterial and parasitic gut infections.

Questions owners ask

Can Metronidazole cause didn't stop worms in dogs?: 143 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 41 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 stop worms with similar medicines

Didn't stop worms after Amoxicillin + Clavulanate (Clavamox) 27 reports · 0.5% of its reports
Didn't stop worms after Doxycycline 79 reports · 2.0% of its reports

All reported side effects of Metronidazole in dogs · Medicines most reported with didn't stop worms