Seizures after Ivermectin (Heartgard) in dogs

686 reports to the FDA describe seizures in dogs given Ivermectin. That is 5.7% of all reports for this medicine, compared with 4.4% across reports for all dog medicines.

686Reports

67%Marked serious

36%Recovered

15%Died or euthanised

28 daysTypical onset

How soon it started

Same day

66 18%

1–2 days

43 11%

3–7 days

27 7.2%

1–4 weeks

58 15%

Over a month

181 48%

How the animals did

Recovered

224 33%

Recovered with lasting effects

24 3.5%

Still unwell when reported

93 14%

Died

69 10%

Euthanised

34 5.0%

Not known

242 35%

Problems reported at the same time

137 20%

117 17%

102 15%

94 14%

92 13%

Eye or vision problems

78 11%

Drooling

77 11%

Behaviour change

44 6.4%

Age of the animals

Under 1 year

109

1–3 years

179

4–7 years

175

8–11 years

122

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 seizures in dogs?: 686 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 28 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).

Seizures with similar medicines

Seizures after Ivermectin + Pyrantel (Heartgard Plus) 3,287 reports · 2.2% of its reports
Seizures after Milbemycin Oxime + Spinosad (Trifexis) 4,483 reports · 3.5% of its reports
Seizures after Moxidectin (ProHeart 6) 2,058 reports · 4.1% of its reports
Seizures after Milbemycin Oxime + Praziquantel (Interceptor Plus) 945 reports · 3.0% of its reports
Seizures after Milbemycin Oxime (Interceptor) 1,089 reports · 3.7% of its reports
Seizures after Selamectin (Revolution) 1,272 reports · 4.3% of its reports
Seizures after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 196 reports · 2.3% of its reports
Seizures after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 90 reports · 7.8% of its reports
Seizures after Ivermectin + Praziquantel 22 reports · 11% of its reports

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