Vomiting after Milbemycin Oxime + Spinosad (Trifexis) in cats

142 reports to the FDA describe vomiting in cats given Milbemycin Oxime + Spinosad. That is 47% of all reports for this medicine, compared with 18% across reports for all cat medicines, so it is reported unusually often with this medicine.

142Reports

6.3%Marked serious

70%Recovered

0.7%Died or euthanised

Same dayTypical onset

How soon it started

Same day

100 78%

1–2 days

17 13%

3–7 days

1 0.8%

1–4 weeks

1 0.8%

Over a month

10 7.8%

How the animals did

Recovered

98 69%

Recovered with lasting effects

2 1.4%

Still unwell when reported

7 4.9%

Died

1 0.7%

Not known

34 24%

Problems reported at the same time

Accidental exposure

38 27%

Lethargy

24 17%

Behaviour change

8 5.6%

Diarrhea

7 4.9%

Loss of appetite

7 4.9%

Drooling

4 2.8%

Blood in vomit

3 2.1%

Hyperglycaemia

2 1.4%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

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 cats?: 142 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 Selamectin (Revolution) 2,379 reports · 11% of its reports
Vomiting after Eprinomectin + Esafoxolaner + Praziquantel (NexGard Combo) 445 reports · 14% of its reports
Vomiting after Ivermectin (Heartgard) 292 reports · 30% of its reports
Vomiting after Eprinomectin + Praziquantel 99 reports · 17% of its reports
Vomiting after Milbemycin Oxime (Interceptor) 69 reports · 17% of its reports
Vomiting after Ivermectin + Pyrantel (Heartgard Plus) 31 reports · 47% of its reports

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