Disorientation after Milbemycin Oxime + Praziquantel (Interceptor Plus) in dogs

The FDA has received 183 reports of disorientation in dogs after Milbemycin Oxime + Praziquantel. 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.

183Reports

45%Marked serious

47%Recovered

5.5%Died or euthanised

8 daysTypical onset

How soon it started

Same day

54 38%

1–2 days

11 7.7%

3–7 days

6 4.2%

1–4 weeks

15 10%

Over a month

57 40%

How the animals did

Recovered

86 47%

Still unwell when reported

52 28%

Died

2 1.1%

Euthanised

8 4.4%

Not known

35 19%

Problems reported at the same time

56 31%

49 27%

46 25%

44 24%

41 22%

40 22%

31 17%

21 11%

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). Praziquantel treats tapeworms.

Products with this combination include Interceptor Plus. 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 + Praziquantel cause disorientation in dogs?: 183 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 8 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).

Disorientation with similar medicines

Disorientation after Ivermectin + Pyrantel (Heartgard Plus) 588 reports · 0.4% of its reports
Disorientation after Milbemycin Oxime + Spinosad (Trifexis) 1,317 reports · 1.0% of its reports
Disorientation after Moxidectin (ProHeart 6) 293 reports · 0.6% of its reports
Disorientation after Milbemycin Oxime (Interceptor) 154 reports · 0.5% of its reports
Disorientation after Selamectin (Revolution) 202 reports · 0.7% of its reports
Disorientation after Ivermectin (Heartgard) 246 reports · 2.0% of its reports
Disorientation after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 45 reports · 0.5% of its reports

All reported side effects of Milbemycin Oxime + Praziquantel in dogs · Medicines most reported with disorientation