Itching after Ivermectin (Heartgard) in dogs

528 reports to the FDA describe itching in dogs given Ivermectin. That is 4.4% of all reports for this medicine, compared with 4.3% across reports for all dog medicines.

528Reports

30%Marked serious

45%Recovered

4.7%Died or euthanised

37 daysTypical onset

How soon it started

Same day

58 19%

1–2 days

28 9.2%

3–7 days

14 4.6%

1–4 weeks

38 12%

Over a month

167 55%

How the animals did

Recovered

141 27%

Recovered with lasting effects

99 19%

Still unwell when reported

80 15%

Died

14 2.7%

Euthanised

11 2.1%

Not known

183 35%

Problems reported at the same time

115 22%

82 16%

73 14%

73 14%

60 11%

50 9.5%

46 8.7%

Eye or vision problems

45 8.5%

Age of the animals

Under 1 year

1–3 years

159

4–7 years

126

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 itching in dogs?: 528 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 37 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).

Itching with similar medicines

Itching after Ivermectin + Pyrantel (Heartgard Plus) 2,733 reports · 1.9% of its reports
Itching after Milbemycin Oxime + Spinosad (Trifexis) 6,069 reports · 4.7% of its reports
Itching after Moxidectin (ProHeart 6) 2,435 reports · 4.8% of its reports
Itching after Milbemycin Oxime + Praziquantel (Interceptor Plus) 763 reports · 2.4% of its reports
Itching after Milbemycin Oxime (Interceptor) 563 reports · 1.9% of its reports
Itching after Selamectin (Revolution) 2,024 reports · 6.9% of its reports
Itching after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 93 reports · 1.1% of its reports
Itching after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 57 reports · 4.9% of its reports

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