Pain after Milbemycin Oxime + Spinosad (Trifexis) in dogs

The FDA has received 572 reports of pain in dogs after Milbemycin Oxime + Spinosad. That is 0.4% of all reports for this medicine, compared with 0.7% across reports for all dog medicines, so it is reported less often than average with this medicine.

572Reports

43%Marked serious

45%Recovered

13%Died or euthanised

1 daysTypical onset

How soon it started

Same day

158 39%

1–2 days

55 13%

3–7 days

15 3.7%

1–4 weeks

38 9.3%

Over a month

143 35%

How the animals did

Recovered

212 37%

Recovered with lasting effects

44 7.7%

Still unwell when reported

82 14%

Died

29 5.1%

Euthanised

47 8.2%

Not known

158 28%

Problems reported at the same time

271 47%

199 35%

171 30%

146 26%

142 25%

141 25%

78 14%

76 13%

Age of the animals

Under 1 year

1–3 years

191

4–7 years

136

8–11 years

108

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 pain in dogs?: 572 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 1 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).

Pain with similar medicines

Pain after Ivermectin + Pyrantel (Heartgard Plus) 330 reports · 0.2% of its reports
Pain after Moxidectin (ProHeart 6) 436 reports · 0.9% of its reports
Pain after Milbemycin Oxime + Praziquantel (Interceptor Plus) 129 reports · 0.4% of its reports
Pain after Milbemycin Oxime (Interceptor) 121 reports · 0.4% of its reports
Pain after Selamectin (Revolution) 159 reports · 0.5% of its reports
Pain after Ivermectin (Heartgard) 63 reports · 0.5% of its reports

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