Liver problems after Milbemycin Oxime + Spinosad (Trifexis) in dogs

2,221 reports to the FDA describe liver problems in dogs given Milbemycin Oxime + Spinosad. That is 1.7% of all reports for this medicine, compared with 4.6% across reports for all dog medicines, so it is reported less often than average with this medicine.

2,221Reports

65%Marked serious

35%Recovered

17%Died or euthanised

23 daysTypical onset

How soon it started

Same day

398 28%

1–2 days

147 10%

3–7 days

76 5.3%

1–4 weeks

129 9.0%

Over a month

680 48%

How the animals did

Recovered

335 15%

Recovered with lasting effects

443 20%

Still unwell when reported

484 22%

Died

170 7.7%

Euthanised

205 9.2%

Not known

584 26%

Problems reported at the same time

896 40%

843 38%

713 32%

378 17%

370 17%

360 16%

288 13%

262 12%

Age of the animals

Under 1 year

215

1–3 years

466

4–7 years

564

8–11 years

596

12+ years

321

About this medicine

Milbemycin Oxime prevents heartworm and controls some intestinal worms (monthly). Spinosad kills fleas; monthly chewable.

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

Some herding breeds (for example Collies) carry the MDR1 gene variant and can be more sensitive to this drug class at high doses.

Questions owners ask

Can Milbemycin Oxime + Spinosad cause liver problems in dogs?: 2,221 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 23 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).

Liver problems with similar medicines

Liver problems after Ivermectin + Pyrantel (Heartgard Plus) 1,518 reports · 1.0% of its reports
Liver problems after Moxidectin (ProHeart 6) 2,025 reports · 4.0% of its reports
Liver problems after Milbemycin Oxime + Praziquantel (Interceptor Plus) 534 reports · 1.7% of its reports
Liver problems after Milbemycin Oxime (Interceptor) 531 reports · 1.8% of its reports
Liver problems after Selamectin (Revolution) 560 reports · 1.9% of its reports
Liver problems after Ivermectin (Heartgard) 369 reports · 3.1% of its reports
Liver problems after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 149 reports · 1.7% of its reports
Liver problems after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 63 reports · 5.4% of its reports

All reported side effects of Milbemycin Oxime + Spinosad in dogs · Medicines most reported with liver problems