Death after Milbemycin Oxime + Spinosad (Trifexis) in dogs

3,307 reports to the FDA describe death in dogs given Milbemycin Oxime + Spinosad. That is 2.5% of all reports for this medicine, compared with 5.2% across reports for all dog medicines, so it is reported less often than average with this medicine.

3,307Reports

98%Marked serious

0.1%Recovered

99%Died or euthanised

14 daysTypical onset

How soon it started

Same day

749 34%

1–2 days

164 7.5%

3–7 days

93 4.2%

1–4 weeks

231 11%

Over a month

952 43%

How the animals did

Recovered

3 0.1%

Still unwell when reported

3 0.1%

Died

2,062 62%

Euthanised

1,227 37%

Not known

12 0.4%

Problems reported at the same time

668 20%

650 20%

572 17%

436 13%

370 11%

357 11%

294 8.9%

278 8.4%

Age of the animals

Under 1 year

216

1–3 years

362

4–7 years

517

8–11 years

730

12+ years

774

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 death in dogs?: 3,307 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).

Death with similar medicines

Death after Ivermectin + Pyrantel (Heartgard Plus) 2,810 reports · 1.9% of its reports
Death after Moxidectin (ProHeart 6) 2,447 reports · 4.8% of its reports
Death after Milbemycin Oxime + Praziquantel (Interceptor Plus) 920 reports · 2.9% of its reports
Death after Milbemycin Oxime (Interceptor) 1,015 reports · 3.4% of its reports
Death after Selamectin (Revolution) 785 reports · 2.7% of its reports
Death after Ivermectin (Heartgard) 609 reports · 5.1% of its reports
Death after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 125 reports · 1.5% of its reports
Death after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 60 reports · 5.2% of its reports

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