Blood problems after Milbemycin Oxime (Interceptor) in dogs

The FDA has received 251 reports of blood problems in dogs after Milbemycin Oxime. That is 0.8% of all reports for this medicine, compared with 1.8% across reports for all dog medicines, so it is reported less often than average with this medicine.

251Reports

32%Marked serious

3.6%Recovered

40%Died or euthanised

30 daysTypical onset

How soon it started

Same day

1 1.8%

1–2 days

7 13%

3–7 days

7 13%

1–4 weeks

14 25%

Over a month

27 48%

How the animals did

Recovered

5 2.0%

Recovered with lasting effects

4 1.6%

Still unwell when reported

37 15%

Died

78 31%

Euthanised

22 8.8%

Not known

105 42%

Problems reported at the same time

120 48%

104 41%

96 38%

78 31%

77 31%

52 21%

41 16%

40 16%

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).

Products with this ingredient include Interceptor. 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 cause blood problems in dogs?: 251 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 30 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).

Blood problems with similar medicines

Blood problems after Ivermectin + Pyrantel (Heartgard Plus) 545 reports · 0.4% of its reports
Blood problems after Milbemycin Oxime + Spinosad (Trifexis) 735 reports · 0.6% of its reports
Blood problems after Moxidectin (ProHeart 6) 1,343 reports · 2.7% of its reports
Blood problems after Milbemycin Oxime + Praziquantel (Interceptor Plus) 225 reports · 0.7% of its reports
Blood problems after Selamectin (Revolution) 327 reports · 1.1% of its reports
Blood problems after Ivermectin (Heartgard) 145 reports · 1.2% of its reports
Blood problems after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 37 reports · 0.4% of its reports
Blood problems after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 30 reports · 2.6% of its reports

All reported side effects of Milbemycin Oxime in dogs · Medicines most reported with blood problems