Tremors after Ivermectin (Heartgard) in dogs

959 reports to the FDA describe tremors in dogs given Ivermectin. That is 8.0% of all reports for this medicine, compared with 3.4% across reports for all dog medicines, so it is reported unusually often with this medicine.

959Reports

30%Marked serious

31%Recovered

10%Died or euthanised

22 daysTypical onset

How soon it started

Same day

93 21%

1–2 days

47 10%

3–7 days

31 6.9%

1–4 weeks

71 16%

Over a month

208 46%

How the animals did

Recovered

244 25%

Recovered with lasting effects

49 5.1%

Still unwell when reported

98 10%

Died

76 7.9%

Euthanised

22 2.3%

Not known

470 49%

Problems reported at the same time

Wobbliness (ataxia)

372 39%

Eye or vision problems

273 28%

221 23%

192 20%

177 18%

137 14%

110 11%

109 11%

Age of the animals

Under 1 year

213

1–3 years

297

4–7 years

172

8–11 years

139

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 tremors in dogs?: 959 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 22 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).

Tremors with similar medicines

Tremors after Ivermectin + Pyrantel (Heartgard Plus) 2,169 reports · 1.5% of its reports
Tremors after Milbemycin Oxime + Spinosad (Trifexis) 5,684 reports · 4.4% of its reports
Tremors after Moxidectin (ProHeart 6) 1,208 reports · 2.4% of its reports
Tremors after Milbemycin Oxime + Praziquantel (Interceptor Plus) 766 reports · 2.4% of its reports
Tremors after Milbemycin Oxime (Interceptor) 729 reports · 2.4% of its reports
Tremors after Selamectin (Revolution) 984 reports · 3.3% of its reports
Tremors after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 245 reports · 2.9% of its reports
Tremors after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 56 reports · 4.8% of its reports
Tremors after Ivermectin + Praziquantel 61 reports · 30% of its reports
Tremors after Moxidectin + Praziquantel 27 reports · 36% of its reports

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