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

The FDA has received 153 reports of underdose in dogs after Milbemycin Oxime + Praziquantel. That is 0.5% 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.

153Reports

10%Marked serious

7.8%Recovered

0.7%Died or euthanised

64 daysTypical onset

How soon it started

Same day

22 23%

1–2 days

7 7.4%

3–7 days

2 2.1%

1–4 weeks

10 11%

Over a month

53 56%

How the animals did

Recovered

12 7.8%

Still unwell when reported

19 12%

Died

1 0.7%

Not known

121 79%

Problems reported at the same time

Didn't prevent heartworm

77 50%

36 24%

22 14%

16 10%

9 5.9%

9 5.9%

Drug administration error

7 4.6%

Medication error

7 4.6%

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 underdose in dogs?: 153 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 64 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).

Underdose with similar medicines

Underdose after Ivermectin + Pyrantel (Heartgard Plus) 1,810 reports · 1.2% of its reports
Underdose after Milbemycin Oxime + Spinosad (Trifexis) 750 reports · 0.6% of its reports
Underdose after Moxidectin (ProHeart 6) 180 reports · 0.4% of its reports
Underdose after Milbemycin Oxime (Interceptor) 118 reports · 0.4% of its reports
Underdose after Selamectin (Revolution) 179 reports · 0.6% of its reports
Underdose after Ivermectin (Heartgard) 99 reports · 0.8% of its reports
Underdose after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 98 reports · 1.1% of its reports

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