Drug dose omission after Ivermectin + Pyrantel (Heartgard Plus) in dogs

503 reports to the FDA describe drug dose omission in dogs given Ivermectin + Pyrantel. That is 0.3% of all reports for this medicine, compared with 0.4% across reports for all dog medicines.

503Reports

56%Marked serious

26%Recovered

0.6%Died or euthanised

234 daysTypical onset

How soon it started

Same day

3 3.7%

1–2 days

3 3.7%

3–7 days

2 2.4%

1–4 weeks

9 11%

Over a month

65 79%

How the animals did

Recovered

28 5.6%

Recovered with lasting effects

103 20%

Still unwell when reported

164 33%

Died

3 0.6%

Not known

205 41%

Problems reported at the same time

Didn't prevent heartworm

433 86%

Cardiac disorder

64 13%

Didn't stop worms

39 7.8%

Didn't work as expected

20 4.0%

Underdose

19 3.8%

Vomiting

19 3.8%

Drug dose administration interval too long

18 3.6%

Digestive tract disorder

17 3.4%

Age of the animals

Under 1 year

1–3 years

214

4–7 years

152

8–11 years

102

12+ years

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 drug dose omission in dogs?: 503 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 234 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).

Drug dose omission with similar medicines

Drug dose omission after Milbemycin Oxime + Spinosad (Trifexis) 1,201 reports · 0.9% of its reports
Drug dose omission after Moxidectin (ProHeart 6) 53 reports · 0.1% of its reports
Drug dose omission after Milbemycin Oxime + Praziquantel (Interceptor Plus) 399 reports · 1.3% of its reports
Drug dose omission after Milbemycin Oxime (Interceptor) 109 reports · 0.4% of its reports
Drug dose omission after Selamectin (Revolution) 87 reports · 0.3% of its reports
Drug dose omission after Ivermectin (Heartgard) 72 reports · 0.6% of its reports
Drug dose omission after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 87 reports · 1.0% of its reports

All reported side effects of Ivermectin + Pyrantel in dogs · Medicines most reported with drug dose omission