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

The FDA has received 194 reports of fever in dogs after Milbemycin Oxime + Praziquantel. That is 0.6% of all reports for this medicine, compared with 1.4% across reports for all dog medicines, so it is reported less often than average with this medicine.

194Reports

48%Marked serious

28%Recovered

11%Died or euthanised

28 daysTypical onset

How soon it started

Same day

28 22%

1–2 days

24 18%

3–7 days

6 4.6%

1–4 weeks

12 9.2%

Over a month

60 46%

How the animals did

Recovered

54 28%

Still unwell when reported

60 31%

Died

10 5.2%

Euthanised

11 5.7%

Not known

59 30%

Problems reported at the same time

89 46%

76 39%

70 36%

45 23%

34 18%

31 16%

29 15%

26 13%

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 fever in dogs?: 194 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 28 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).

Fever with similar medicines

Fever after Ivermectin + Pyrantel (Heartgard Plus) 597 reports · 0.4% of its reports
Fever after Milbemycin Oxime + Spinosad (Trifexis) 881 reports · 0.7% of its reports
Fever after Moxidectin (ProHeart 6) 1,914 reports · 3.8% of its reports
Fever after Milbemycin Oxime (Interceptor) 255 reports · 0.9% of its reports
Fever after Selamectin (Revolution) 322 reports · 1.1% of its reports
Fever after Ivermectin (Heartgard) 154 reports · 1.3% of its reports
Fever after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 33 reports · 0.4% of its reports
Fever after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 20 reports · 1.7% of its reports

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