Behaviour change after Milbemycin Oxime + Praziquantel (Interceptor Plus) in dogs

852 reports to the FDA describe behaviour change in dogs given Milbemycin Oxime + Praziquantel. That is 2.7% of all reports for this medicine, compared with 2.5% across reports for all dog medicines.

852Reports

26%Marked serious

33%Recovered

4.8%Died or euthanised

4 daysTypical onset

How soon it started

Same day

229 37%

1–2 days

66 11%

3–7 days

36 5.9%

1–4 weeks

52 8.5%

Over a month

232 38%

How the animals did

Recovered

273 32%

Recovered with lasting effects

5 0.6%

Still unwell when reported

274 32%

Died

11 1.3%

Euthanised

30 3.5%

Not known

259 30%

Problems reported at the same time

252 30%

212 25%

169 20%

134 16%

96 11%

83 9.7%

77 9.0%

67 7.9%

Age of the animals

Under 1 year

124

1–3 years

253

4–7 years

217

8–11 years

158

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 behaviour change in dogs?: 852 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).

Behaviour change with similar medicines

Behaviour change after Ivermectin + Pyrantel (Heartgard Plus) 1,674 reports · 1.1% of its reports
Behaviour change after Milbemycin Oxime + Spinosad (Trifexis) 4,099 reports · 3.2% of its reports
Behaviour change after Moxidectin (ProHeart 6) 688 reports · 1.4% of its reports
Behaviour change after Milbemycin Oxime (Interceptor) 364 reports · 1.2% of its reports
Behaviour change after Selamectin (Revolution) 652 reports · 2.2% of its reports
Behaviour change after Ivermectin (Heartgard) 368 reports · 3.1% of its reports
Behaviour change after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 146 reports · 1.7% of its reports
Behaviour change after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 55 reports · 4.7% of its reports

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