Didn't work as expected after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) in dogs

1,337 reports to the FDA describe didn't work as expected in dogs given Ivermectin + Praziquantel + Pyrantel. That is 16% of all reports for this medicine, compared with 13% across reports for all dog medicines.

1,337Reports

2.9%Marked serious

11%Recovered

0.2%Died or euthanised

18 daysTypical onset

How soon it started

Same day

66 7.2%

1–2 days

44 4.8%

3–7 days

110 12%

1–4 weeks

518 56%

Over a month

179 20%

How the animals did

Recovered

133 9.9%

Recovered with lasting effects

14 1.0%

Still unwell when reported

40 3.0%

Died

2 0.1%

Euthanised

1 0.1%

Not known

1,147 86%

Problems reported at the same time

Didn't stop worms

492 37%

Didn't prevent heartworm

262 20%

73 5.5%

46 3.4%

23 1.7%

18 1.3%

16 1.2%

Incorrect dose administered

16 1.2%

Age of the animals

Under 1 year

106

1–3 years

467

4–7 years

389

8–11 years

243

12+ years

About this medicine

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

Products with this combination include Iverhart Max. 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 + Praziquantel + Pyrantel cause didn't work as expected in dogs?: 1,337 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 18 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).

Didn't work as expected with similar medicines

Didn't work as expected after Ivermectin + Pyrantel (Heartgard Plus) 27,781 reports · 19% of its reports
Didn't work as expected after Milbemycin Oxime + Spinosad (Trifexis) 13,050 reports · 10% of its reports
Didn't work as expected after Moxidectin (ProHeart 6) 2,005 reports · 4.0% of its reports
Didn't work as expected after Milbemycin Oxime + Praziquantel (Interceptor Plus) 3,979 reports · 13% of its reports
Didn't work as expected after Milbemycin Oxime (Interceptor) 3,131 reports · 11% of its reports
Didn't work as expected after Selamectin (Revolution) 2,253 reports · 7.7% of its reports
Didn't work as expected after Ivermectin (Heartgard) 741 reports · 6.2% of its reports
Didn't work as expected after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 123 reports · 11% of its reports

All reported side effects of Ivermectin + Praziquantel + Pyrantel in dogs · Medicines most reported with didn't work as expected