Tachycardia after Milbemycin Oxime (Interceptor) in dogs

The FDA has received 78 reports of tachycardia in dogs after Milbemycin Oxime. That is 0.3% of all reports for this medicine, compared with 0.5% across reports for all dog medicines, so it is reported less often than average with this medicine.

78Reports

24%Marked serious

7.7%Recovered

24%Died or euthanised

27 daysTypical onset

How soon it started

Same day

5 31%

1–2 days

0 0.0%

3–7 days

2 13%

1–4 weeks

2 13%

Over a month

7 44%

How the animals did

Recovered

6 7.7%

Still unwell when reported

4 5.1%

Died

15 19%

Euthanised

4 5.1%

Not known

49 63%

Problems reported at the same time

32 41%

27 35%

27 35%

21 27%

20 26%

19 24%

18 23%

13 17%

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).

Products with this ingredient include Interceptor. 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 cause tachycardia in dogs?: 78 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 27 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).

Tachycardia with similar medicines

Tachycardia after Ivermectin + Pyrantel (Heartgard Plus) 204 reports · 0.1% of its reports
Tachycardia after Milbemycin Oxime + Spinosad (Trifexis) 209 reports · 0.2% of its reports
Tachycardia after Moxidectin (ProHeart 6) 628 reports · 1.2% of its reports
Tachycardia after Milbemycin Oxime + Praziquantel (Interceptor Plus) 55 reports · 0.2% of its reports
Tachycardia after Selamectin (Revolution) 86 reports · 0.3% of its reports
Tachycardia after Ivermectin (Heartgard) 82 reports · 0.7% of its reports
Tachycardia after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 32 reports · 0.4% of its reports

All reported side effects of Milbemycin Oxime in dogs · Medicines most reported with tachycardia