Loose stool after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) in dogs

The FDA has received 120 reports of loose stool in dogs after Ivermectin + Praziquantel + Pyrantel. That is 1.4% of all reports for this medicine, compared with 0.9% across reports for all dog medicines, so it is reported unusually often with this medicine.

120Reports

18%Marked serious

56%Recovered

1.7%Died or euthanised

Same dayTypical onset

How soon it started

Same day

61 56%

1–2 days

18 17%

3–7 days

6 5.5%

1–4 weeks

16 15%

Over a month

8 7.3%

How the animals did

Recovered

67 56%

Still unwell when reported

5 4.2%

Died

2 1.7%

Not known

46 38%

Problems reported at the same time

Vomiting

49 41%

Lethargy

25 21%

Didn't stop worms

18 15%

Didn't work as expected

16 13%

12 10%

9 7.5%

7 5.8%

5 4.2%

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 loose stool in dogs?: 120 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 the same day 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).

Loose stool with similar medicines

Loose stool after Ivermectin + Pyrantel (Heartgard Plus) 1,339 reports · 0.9% of its reports
Loose stool after Milbemycin Oxime + Spinosad (Trifexis) 885 reports · 0.7% of its reports
Loose stool after Moxidectin (ProHeart 6) 332 reports · 0.7% of its reports
Loose stool after Milbemycin Oxime + Praziquantel (Interceptor Plus) 406 reports · 1.3% of its reports
Loose stool after Milbemycin Oxime (Interceptor) 327 reports · 1.1% of its reports
Loose stool after Selamectin (Revolution) 156 reports · 0.5% of its reports
Loose stool after Ivermectin (Heartgard) 88 reports · 0.7% of its reports

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