Skin redness after Milbemycin Oxime + Spinosad (Trifexis) in dogs

The FDA has received 828 reports of skin redness in dogs after Milbemycin Oxime + Spinosad. That is 0.6% of all reports for this medicine, compared with 1.0% across reports for all dog medicines, so it is reported less often than average with this medicine.

828Reports

29%Marked serious

52%Recovered

2.9%Died or euthanised

1 daysTypical onset

How soon it started

Same day

283 44%

1–2 days

83 13%

3–7 days

31 4.8%

1–4 weeks

40 6.2%

Over a month

212 33%

How the animals did

Recovered

280 34%

Recovered with lasting effects

153 18%

Still unwell when reported

166 20%

Died

13 1.6%

Euthanised

11 1.3%

Not known

205 25%

Problems reported at the same time

264 32%

242 29%

194 23%

152 18%

93 11%

86 10%

Skin rash or irritation

86 10%

Behaviour change

85 10%

Age of the animals

Under 1 year

130

1–3 years

319

4–7 years

202

8–11 years

117

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 redness in dogs?: 828 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).

Skin redness with similar medicines

Skin redness after Ivermectin + Pyrantel (Heartgard Plus) 491 reports · 0.3% of its reports
Skin redness after Moxidectin (ProHeart 6) 1,035 reports · 2.0% of its reports
Skin redness after Milbemycin Oxime + Praziquantel (Interceptor Plus) 163 reports · 0.5% of its reports
Skin redness after Milbemycin Oxime (Interceptor) 71 reports · 0.2% of its reports
Skin redness after Selamectin (Revolution) 365 reports · 1.2% of its reports
Skin redness after Ivermectin (Heartgard) 105 reports · 0.9% of its reports
Skin redness after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 24 reports · 2.1% of its reports

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