Accidental exposure after Milbemycin Oxime + Spinosad (Trifexis) in cats

The FDA has received 96 reports of accidental exposure in cats after Milbemycin Oxime + Spinosad. That is 32% of all reports for this medicine, compared with 2.6% across reports for all cat medicines, so it is reported unusually often with this medicine.

96Reports

23%Marked serious

61%Recovered

0.0%Died or euthanised

Same dayTypical onset

How soon it started

Same day

49 64%

1–2 days

19 25%

3–7 days

1 1.3%

1–4 weeks

5 6.5%

Over a month

3 3.9%

How the animals did

Recovered

54 56%

Recovered with lasting effects

5 5.2%

Still unwell when reported

14 15%

Not known

23 24%

Problems reported at the same time

38 40%

32 33%

17 18%

13 14%

Tremors

8 8.3%

Diarrhea

5 5.2%

Behaviour change

5 5.2%

Itching

5 5.2%

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 accidental exposure in cats?: 96 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).

Accidental exposure with similar medicines

Accidental exposure after Selamectin (Revolution) 352 reports · 1.6% of its reports
Accidental exposure after Eprinomectin + Esafoxolaner + Praziquantel (NexGard Combo) 153 reports · 4.7% of its reports
Accidental exposure after Ivermectin (Heartgard) 53 reports · 5.5% of its reports
Accidental exposure after Milbemycin Oxime (Interceptor) 36 reports · 8.9% of its reports
Accidental exposure after Ivermectin + Pyrantel (Heartgard Plus) 37 reports · 56% of its reports

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