Diarrhea after Ivermectin + Pyrantel (Heartgard Plus) in dogs

The FDA has received 9,076 reports of diarrhea in dogs after Ivermectin + Pyrantel. That is 6.1% of all reports for this medicine, compared with 8.4% across reports for all dog medicines.

9,076Reports

44%Marked serious

27%Recovered

2.4%Died or euthanised

3 daysTypical onset

How soon it started

Same day

1,353 29%

1–2 days

921 20%

3–7 days

248 5.4%

1–4 weeks

514 11%

Over a month

1,551 34%

How the animals did

Recovered

2,442 27%

Recovered with lasting effects

45 0.5%

Still unwell when reported

797 8.8%

Died

146 1.6%

Euthanised

69 0.8%

Not known

5,577 61%

Problems reported at the same time

Vomiting

3,812 42%

Didn't stop worms

1,972 22%

Digestive tract disorder

1,802 20%

Lethargy

1,578 17%

Loss of appetite

1,340 15%

Didn't work as expected

1,187 13%

Liver problems

275 3.0%

Tremors

219 2.4%

Age of the animals

Under 1 year

1,853

1–3 years

2,749

4–7 years

2,058

8–11 years

1,343

12+ years

641

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 diarrhea in dogs?: 9,076 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 3 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).

Diarrhea with similar medicines

Diarrhea after Milbemycin Oxime + Spinosad (Trifexis) 7,183 reports · 5.5% of its reports
Diarrhea after Moxidectin (ProHeart 6) 4,291 reports · 8.5% of its reports
Diarrhea after Milbemycin Oxime + Praziquantel (Interceptor Plus) 2,695 reports · 8.5% of its reports
Diarrhea after Milbemycin Oxime (Interceptor) 2,873 reports · 9.7% of its reports
Diarrhea after Selamectin (Revolution) 1,974 reports · 6.7% of its reports
Diarrhea after Ivermectin (Heartgard) 693 reports · 5.8% of its reports
Diarrhea after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 954 reports · 11% of its reports
Diarrhea after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 125 reports · 11% of its reports

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