Seizures after Ivermectin + Pyrantel (Heartgard Plus) in dogs

3,287 reports to the FDA describe seizures in dogs given Ivermectin + Pyrantel. That is 2.2% of all reports for this medicine, compared with 4.4% across reports for all dog medicines, so it is reported less often than average with this medicine.

3,287Reports

58%Marked serious

36%Recovered

9.1%Died or euthanised

5 daysTypical onset

How soon it started

Same day

417 24%

1–2 days

307 18%

3–7 days

190 11%

1–4 weeks

338 20%

Over a month

459 27%

How the animals did

Recovered

1,143 35%

Recovered with lasting effects

41 1.2%

Still unwell when reported

311 9.5%

Died

184 5.6%

Euthanised

116 3.5%

Not known

1,492 45%

Problems reported at the same time

406 12%

354 11%

296 9.0%

293 8.9%

251 7.6%

212 6.4%

212 6.4%

207 6.3%

Age of the animals

Under 1 year

273

1–3 years

900

4–7 years

1,064

8–11 years

597

12+ years

302

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 seizures in dogs?: 3,287 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 5 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 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 (Heartgard) 686 reports · 5.7% 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 + Pyrantel in dogs · Medicines most reported with seizures