Swelling after Ivermectin (Heartgard) in dogs

The FDA has received 204 reports of swelling in dogs after Ivermectin. That is 1.7% of all reports for this medicine, compared with 2.8% across reports for all dog medicines, so it is reported less often than average with this medicine.

204Reports

37%Marked serious

19%Recovered

18%Died or euthanised

12 daysTypical onset

How soon it started

Same day

44 34%

1–2 days

13 9.9%

3–7 days

4 3.1%

1–4 weeks

17 13%

Over a month

53 40%

How the animals did

Recovered

35 17%

Recovered with lasting effects

3 1.5%

Still unwell when reported

64 31%

Died

23 11%

Euthanised

14 6.9%

Not known

65 32%

Problems reported at the same time

47 23%

44 22%

44 22%

36 18%

35 17%

27 13%

22 11%

21 10%

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 swelling in dogs?: 204 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 12 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).

Swelling with similar medicines

Swelling after Ivermectin + Pyrantel (Heartgard Plus) 839 reports · 0.6% of its reports
Swelling after Milbemycin Oxime + Spinosad (Trifexis) 959 reports · 0.7% of its reports
Swelling after Moxidectin (ProHeart 6) 7,913 reports · 16% of its reports
Swelling after Milbemycin Oxime + Praziquantel (Interceptor Plus) 371 reports · 1.2% of its reports
Swelling after Milbemycin Oxime (Interceptor) 257 reports · 0.9% of its reports
Swelling after Selamectin (Revolution) 410 reports · 1.4% of its reports
Swelling after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 66 reports · 0.8% of its reports
Swelling after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 22 reports · 1.9% of its reports

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