Skin rash or irritation after Milbemycin Oxime + Spinosad (Trifexis) in dogs

1,342 reports to the FDA describe skin rash or irritation in dogs given Milbemycin Oxime + Spinosad. That is 1.0% of all reports for this medicine, compared with 1.3% across reports for all dog medicines.

1,342Reports

23%Marked serious

43%Recovered

2.9%Died or euthanised

14 daysTypical onset

How soon it started

Same day

285 31%

1–2 days

88 9.5%

3–7 days

52 5.6%

1–4 weeks

117 13%

Over a month

385 42%

How the animals did

Recovered

292 22%

Recovered with lasting effects

279 21%

Still unwell when reported

289 22%

Died

20 1.5%

Euthanised

19 1.4%

Not known

443 33%

Problems reported at the same time

461 34%

334 25%

175 13%

159 12%

154 11%

140 10%

Didn't work as expected

134 10.0%

Didn't prevent heartworm

125 9.3%

Age of the animals

Under 1 year

167

1–3 years

434

4–7 years

375

8–11 years

235

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 skin rash or irritation in dogs?: 1,342 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).

Skin rash or irritation with similar medicines

Skin rash or irritation after Ivermectin + Pyrantel (Heartgard Plus) 664 reports · 0.4% of its reports
Skin rash or irritation after Moxidectin (ProHeart 6) 446 reports · 0.9% of its reports
Skin rash or irritation after Milbemycin Oxime + Praziquantel (Interceptor Plus) 234 reports · 0.7% of its reports
Skin rash or irritation after Milbemycin Oxime (Interceptor) 234 reports · 0.8% of its reports
Skin rash or irritation after Selamectin (Revolution) 728 reports · 2.5% of its reports
Skin rash or irritation after Ivermectin (Heartgard) 138 reports · 1.1% of its reports
Skin rash or irritation after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 20 reports · 0.2% of its reports

All reported side effects of Milbemycin Oxime + Spinosad in dogs · Medicines most reported with skin rash or irritation