Didn't prevent heartworm after Trifexis in dogs

57 reports to the FDA describe didn't prevent heartworm in dogs given Trifexis. That is 65% of all reports for this medicine, compared with 13% across reports for all dog medicines, so it is reported unusually often with this medicine.

57Reports
93%Marked serious
0.0%Recovered
0.0%Died or euthanised
278 daysTypical onset
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How soon it started

Same day
0 0.0%
1–2 days
0 0.0%
3–7 days
0 0.0%
1–4 weeks
0 0.0%
Over a month
18 100%

How the animals did

Still unwell when reported
55 96%
Not known
2 3.5%

Problems reported at the same time

Drug dose administration interval too long
3 5.3%
Drug dose administration interval too short
2 3.5%
Drug dose omission
2 3.5%
Overdose
1 1.8%
Medication error
1 1.8%

Age of the animals

Under 1 year
2
1–3 years
30
4–7 years
13
8–11 years
11
12+ years
1

About this medicine

Type: medicine.

Questions owners ask

Can Trifexis cause didn't prevent heartworm in dogs?
57 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 278 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 prevent heartworm with similar medicines

All reported side effects of Trifexis in dogs · Medicines most reported with didn't prevent heartworm