Underdose after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) in dogs

The FDA has received 98 reports of underdose in dogs after Ivermectin + Praziquantel + Pyrantel. That is 1.1% of all reports for this medicine, compared with 1.0% across reports for all dog medicines.

98Reports

14%Marked serious

28%Recovered

1.0%Died or euthanised

24 daysTypical onset

How soon it started

Same day

10 19%

1–2 days

0 0.0%

3–7 days

4 7.7%

1–4 weeks

17 33%

Over a month

21 40%

How the animals did

Recovered

25 26%

Recovered with lasting effects

2 2.0%

Still unwell when reported

3 3.1%

Euthanised

1 1.0%

Not known

67 68%

Problems reported at the same time

Didn't prevent heartworm

51 52%

Didn't stop worms

25 26%

Didn't work as expected

23 23%

Incorrect dose administered

12 12%

Vomiting

8 8.2%

Diarrhea

6 6.1%

Weight gain

5 5.1%

Drug dose administration interval too long

5 5.1%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

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 underdose in dogs?: 98 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 24 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).

Underdose with similar medicines

Underdose after Ivermectin + Pyrantel (Heartgard Plus) 1,810 reports · 1.2% of its reports
Underdose after Milbemycin Oxime + Spinosad (Trifexis) 750 reports · 0.6% of its reports
Underdose after Moxidectin (ProHeart 6) 180 reports · 0.4% of its reports
Underdose after Milbemycin Oxime + Praziquantel (Interceptor Plus) 153 reports · 0.5% of its reports
Underdose after Milbemycin Oxime (Interceptor) 118 reports · 0.4% of its reports
Underdose after Selamectin (Revolution) 179 reports · 0.6% of its reports
Underdose after Ivermectin (Heartgard) 99 reports · 0.8% of its reports

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