Seizures after Milbemycin Oxime (Interceptor) in dogs

1,089 reports to the FDA describe seizures in dogs given Milbemycin Oxime. That is 3.7% of all reports for this medicine, compared with 4.4% across reports for all dog medicines.

1,089Reports

28%Marked serious

15%Recovered

9.2%Died or euthanised

4 daysTypical onset

How soon it started

Same day

64 28%

1–2 days

44 19%

3–7 days

25 11%

1–4 weeks

28 12%

Over a month

71 31%

How the animals did

Recovered

153 14%

Recovered with lasting effects

9 0.8%

Still unwell when reported

109 10%

Died

84 7.7%

Euthanised

16 1.5%

Not known

718 66%

Problems reported at the same time

108 9.9%

98 9.0%

98 9.0%

93 8.5%

66 6.1%

65 6.0%

52 4.8%

45 4.1%

Age of the animals

Under 1 year

112

1–3 years

319

4–7 years

368

8–11 years

176

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 seizures in dogs?: 1,089 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 4 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).

Seizures with similar medicines

Seizures after Ivermectin + Pyrantel (Heartgard Plus) 3,287 reports · 2.2% of its reports
Seizures after Milbemycin Oxime + Spinosad (Trifexis) 4,483 reports · 3.5% of its reports
Seizures after Moxidectin (ProHeart 6) 2,058 reports · 4.1% of its reports
Seizures after Milbemycin Oxime + Praziquantel (Interceptor Plus) 945 reports · 3.0% of its reports
Seizures after Selamectin (Revolution) 1,272 reports · 4.3% of its reports
Seizures after Ivermectin (Heartgard) 686 reports · 5.7% of its reports
Seizures after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 196 reports · 2.3% of its reports
Seizures after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 90 reports · 7.8% of its reports
Seizures after Ivermectin + Praziquantel 22 reports · 11% of its reports

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