Overdose after Ivermectin + Pyrantel (Heartgard Plus) in dogs

The FDA has received 1,647 reports of overdose in dogs after Ivermectin + Pyrantel. That is 1.1% of all reports for this medicine, compared with 1.3% across reports for all dog medicines.

1,647Reports

41%Marked serious

34%Recovered

1.2%Died or euthanised

19 daysTypical onset

How soon it started

Same day

136 22%

1–2 days

61 9.7%

3–7 days

37 5.9%

1–4 weeks

177 28%

Over a month

216 34%

How the animals did

Recovered

264 16%

Recovered with lasting effects

294 18%

Still unwell when reported

201 12%

Died

11 0.7%

Euthanised

8 0.5%

Not known

869 53%

Problems reported at the same time

Didn't prevent heartworm

613 37%

Didn't stop worms

346 21%

Accidental exposure

290 18%

Didn't work as expected

282 17%

Digestive tract disorder

211 13%

Vomiting

204 12%

Diarrhea

140 8.5%

Cardiac disorder

140 8.5%

Age of the animals

Under 1 year

191

1–3 years

597

4–7 years

411

8–11 years

274

12+ years

133

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 overdose in dogs?: 1,647 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 19 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).

Overdose with similar medicines

Overdose after Milbemycin Oxime + Spinosad (Trifexis) 2,052 reports · 1.6% of its reports
Overdose after Moxidectin (ProHeart 6) 366 reports · 0.7% of its reports
Overdose after Milbemycin Oxime + Praziquantel (Interceptor Plus) 266 reports · 0.8% of its reports
Overdose after Milbemycin Oxime (Interceptor) 131 reports · 0.4% of its reports
Overdose after Selamectin (Revolution) 160 reports · 0.5% of its reports
Overdose after Ivermectin (Heartgard) 134 reports · 1.1% of its reports
Overdose after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 185 reports · 2.2% of its reports
Overdose after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 31 reports · 2.7% of its reports

All reported side effects of Ivermectin + Pyrantel in dogs · Medicines most reported with overdose