Allergic reaction after Ivermectin (Heartgard) in dogs

The FDA has received 160 reports of allergic reaction in dogs after Ivermectin. That is 1.3% of all reports for this medicine, compared with 2.3% across reports for all dog medicines, so it is reported less often than average with this medicine.

160Reports

35%Marked serious

38%Recovered

1.9%Died or euthanised

1 daysTypical onset

How soon it started

Same day

49 46%

1–2 days

7 6.6%

3–7 days

7 6.6%

1–4 weeks

8 7.5%

Over a month

35 33%

How the animals did

Recovered

54 34%

Recovered with lasting effects

7 4.4%

Still unwell when reported

38 24%

Died

2 1.3%

Euthanised

1 0.6%

Not known

58 36%

Problems reported at the same time

60 38%

44 28%

36 23%

35 22%

24 15%

16 10%

15 9.4%

14 8.8%

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 allergic reaction in dogs?: 160 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 1 day 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).

Allergic reaction with similar medicines

Allergic reaction after Ivermectin + Pyrantel (Heartgard Plus) 788 reports · 0.5% of its reports
Allergic reaction after Milbemycin Oxime + Spinosad (Trifexis) 1,103 reports · 0.9% of its reports
Allergic reaction after Moxidectin (ProHeart 6) 9,936 reports · 20% of its reports
Allergic reaction after Milbemycin Oxime + Praziquantel (Interceptor Plus) 402 reports · 1.3% of its reports
Allergic reaction after Milbemycin Oxime (Interceptor) 274 reports · 0.9% of its reports
Allergic reaction after Selamectin (Revolution) 473 reports · 1.6% of its reports
Allergic reaction after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 70 reports · 0.8% of its reports

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