Didn't stop worms after Milbemycin Oxime + Praziquantel (Interceptor Plus) in dogs

6,097 reports to the FDA describe didn't stop worms in dogs given Milbemycin Oxime + Praziquantel. That is 19% of all reports for this medicine, compared with 8.4% across reports for all dog medicines, so it is reported unusually often with this medicine.

6,097Reports

3.9%Marked serious

1.7%Recovered

0.3%Died or euthanised

71 daysTypical onset

How soon it started

Same day

84 2.7%

1–2 days

82 2.7%

3–7 days

123 4.0%

1–4 weeks

697 23%

Over a month

2,099 68%

How the animals did

Recovered

93 1.5%

Recovered with lasting effects

8 0.1%

Still unwell when reported

327 5.4%

Died

9 0.1%

Euthanised

7 0.1%

Not known

5,653 93%

Problems reported at the same time

Didn't work as expected

528 8.7%

381 6.2%

250 4.1%

114 1.9%

111 1.8%

82 1.3%

78 1.3%

Didn't prevent heartworm

76 1.2%

Age of the animals

Under 1 year

1,040

1–3 years

2,076

4–7 years

1,487

8–11 years

934

12+ years

349

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 didn't stop worms in dogs?: 6,097 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 71 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).

Didn't stop worms with similar medicines

Didn't stop worms after Ivermectin + Pyrantel (Heartgard Plus) 32,467 reports · 22% of its reports
Didn't stop worms after Milbemycin Oxime + Spinosad (Trifexis) 4,483 reports · 3.5% of its reports
Didn't stop worms after Moxidectin (ProHeart 6) 9,537 reports · 19% of its reports
Didn't stop worms after Milbemycin Oxime (Interceptor) 4,308 reports · 14% of its reports
Didn't stop worms after Selamectin (Revolution) 2,317 reports · 7.9% of its reports
Didn't stop worms after Ivermectin (Heartgard) 254 reports · 2.1% of its reports
Didn't stop worms after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 1,299 reports · 15% of its reports
Didn't stop worms after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 132 reports · 11% of its reports

All reported side effects of Milbemycin Oxime + Praziquantel in dogs · Medicines most reported with didn't stop worms