Overdose after Ivermectin (Heartgard) in dogs

The FDA has received 134 reports of overdose in dogs after Ivermectin. That is 1.1% of all reports for this medicine, compared with 1.3% across reports for all dog medicines.

134Reports

38%Marked serious

39%Recovered

5.2%Died or euthanised

78 daysTypical onset

How soon it started

Same day

9 16%

1–2 days

5 9.1%

3–7 days

3 5.5%

1–4 weeks

7 13%

Over a month

31 56%

How the animals did

Recovered

46 34%

Recovered with lasting effects

6 4.5%

Still unwell when reported

26 19%

Died

4 3.0%

Euthanised

3 2.2%

Not known

49 37%

Problems reported at the same time

Accidental exposure

35 26%

Didn't prevent heartworm

33 25%

32 24%

26 19%

17 13%

15 11%

Didn't work as expected

13 9.7%

Labelled drug-drug interaction medication error

13 9.7%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Ivermectin prevents heartworm disease (monthly).

Products with this ingredient include Heartgard. 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 Ivermectin cause overdose in dogs?: 134 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 78 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).

Overdose with similar medicines

Overdose after Ivermectin + Pyrantel (Heartgard Plus) 1,647 reports · 1.1% of its reports
Overdose after Milbemycin Oxime + Spinosad (Trifexis) 2,052 reports · 1.6% of its reports
Overdose after Moxidectin (ProHeart 6) 366 reports · 0.7% of its reports
Overdose after Milbemycin Oxime + Praziquantel (Interceptor Plus) 266 reports · 0.8% of its reports
Overdose after Milbemycin Oxime (Interceptor) 131 reports · 0.4% of its reports
Overdose after Selamectin (Revolution) 160 reports · 0.5% of its reports
Overdose after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 185 reports · 2.2% of its reports
Overdose after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 31 reports · 2.7% of its reports

All reported side effects of Ivermectin in dogs · Medicines most reported with overdose