Foaming at the mouth after Milbemycin Oxime + Praziquantel (Interceptor Plus) in dogs

The FDA has received 62 reports of foaming at the mouth in dogs after Milbemycin Oxime + Praziquantel. That is 0.2% of all reports for this medicine, compared with 0.2% across reports for all dog medicines.

62Reports

50%Marked serious

35%Recovered

13%Died or euthanised

9 daysTypical onset

How soon it started

Same day

13 27%

1–2 days

7 15%

3–7 days

3 6.3%

1–4 weeks

7 15%

Over a month

18 38%

How the animals did

Recovered

21 34%

Recovered with lasting effects

1 1.6%

Still unwell when reported

22 35%

Died

3 4.8%

Euthanised

5 8.1%

Not known

10 16%

Problems reported at the same time

31 50%

17 27%

16 26%

12 19%

9 15%

8 13%

8 13%

8 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 foaming at the mouth in dogs?: 62 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 9 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).

Foaming at the mouth with similar medicines

Foaming at the mouth after Ivermectin + Pyrantel (Heartgard Plus) 224 reports · 0.2% of its reports
Foaming at the mouth after Milbemycin Oxime + Spinosad (Trifexis) 221 reports · 0.2% of its reports
Foaming at the mouth after Moxidectin (ProHeart 6) 34 reports · 0.1% of its reports
Foaming at the mouth after Selamectin (Revolution) 32 reports · 0.1% of its reports
Foaming at the mouth after Ivermectin (Heartgard) 21 reports · 0.2% of its reports

All reported side effects of Milbemycin Oxime + Praziquantel in dogs · Medicines most reported with foaming at the mouth