Tremors after Ivermectin + Pyrantel (Heartgard Plus) in dogs

2,169 reports to the FDA describe tremors in dogs given Ivermectin + Pyrantel. That is 1.5% of all reports for this medicine, compared with 3.4% across reports for all dog medicines, so it is reported less often than average with this medicine.

2,169Reports

41%Marked serious

36%Recovered

4.0%Died or euthanised

2 daysTypical onset

How soon it started

Same day

429 34%

1–2 days

242 19%

3–7 days

96 7.7%

1–4 weeks

182 15%

Over a month

301 24%

How the animals did

Recovered

769 35%

Recovered with lasting effects

17 0.8%

Still unwell when reported

213 9.8%

Died

43 2.0%

Euthanised

44 2.0%

Not known

1,083 50%

Problems reported at the same time

582 27%

513 24%

406 19%

382 18%

274 13%

219 10%

214 9.9%

197 9.1%

Age of the animals

Under 1 year

330

1–3 years

666

4–7 years

573

8–11 years

349

12+ years

182

About this medicine

Ivermectin prevents heartworm disease (monthly). Pyrantel treats roundworms and hookworms.

Products with this combination include Heartgard Plus, Tri-Heart Plus, Iverhart Plus. 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 + Pyrantel cause tremors in dogs?: 2,169 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 2 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 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 (Heartgard) 959 reports · 8.0% 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 + Pyrantel in dogs · Medicines most reported with tremors