Vomiting after Milbemycin Oxime + Spinosad (Trifexis) in dogs

The FDA has received 75,323 reports of vomiting in dogs after Milbemycin Oxime + Spinosad. That is 58% of all reports for this medicine, compared with 28% across reports for all dog medicines, so it is reported unusually often with this medicine.

75,323Reports

6.0%Marked serious

85%Recovered

0.9%Died or euthanised

Same dayTypical onset

How soon it started

Same day

34,146 59%

1–2 days

1,969 3.4%

3–7 days

515 0.9%

1–4 weeks

2,178 3.8%

Over a month

18,587 32%

How the animals did

Recovered

62,194 83%

Recovered with lasting effects

1,932 2.6%

Still unwell when reported

2,474 3.3%

Died

401 0.5%

Euthanised

293 0.4%

Not known

8,029 11%

Problems reported at the same time

9,216 12%

4,197 5.6%

3,867 5.1%

1,869 2.5%

1,563 2.1%

1,294 1.7%

1,264 1.7%

Didn't work as expected

1,050 1.4%

Age of the animals

Under 1 year

15,772

1–3 years

28,381

4–7 years

17,876

8–11 years

7,855

12+ years

2,553

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 vomiting in dogs?: 75,323 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 the same day 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).

Vomiting with similar medicines

Vomiting after Ivermectin + Pyrantel (Heartgard Plus) 20,052 reports · 14% of its reports
Vomiting after Moxidectin (ProHeart 6) 12,413 reports · 25% of its reports
Vomiting after Milbemycin Oxime + Praziquantel (Interceptor Plus) 7,113 reports · 23% of its reports
Vomiting after Milbemycin Oxime (Interceptor) 4,379 reports · 15% of its reports
Vomiting after Selamectin (Revolution) 3,074 reports · 10% of its reports
Vomiting after Ivermectin (Heartgard) 3,182 reports · 26% of its reports
Vomiting after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 3,567 reports · 42% of its reports
Vomiting after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 197 reports · 17% of its reports
Vomiting after Ivermectin + Praziquantel 40 reports · 20% of its reports
Vomiting after Eprinomectin 20 reports · 19% of its reports

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