Digestive tract disorder after Ivermectin + Pyrantel (Heartgard Plus) in dogs

16,532 reports to the FDA describe digestive tract disorder in dogs given Ivermectin + Pyrantel. That is 11% of all reports for this medicine, compared with 2.0% across reports for all dog medicines, so it is reported unusually often with this medicine.

16,532Reports

97%Marked serious

3.3%Recovered

0.3%Died or euthanised

148 daysTypical onset

How soon it started

Same day

117 1.9%

1–2 days

48 0.8%

3–7 days

68 1.1%

1–4 weeks

413 6.8%

Over a month

5,420 89%

How the animals did

Recovered

526 3.2%

Recovered with lasting effects

24 0.1%

Still unwell when reported

1,249 7.6%

Died

37 0.2%

Euthanised

20 0.1%

Not known

14,676 89%

Problems reported at the same time

Didn't stop worms

10,665 65%

Didn't work as expected

9,778 59%

Diarrhea

1,802 11%

Vomiting

954 5.8%

Loose stool

440 2.7%

Drug dose administration interval too long

362 2.2%

Loss of appetite

351 2.1%

Lethargy

256 1.5%

Age of the animals

Under 1 year

1,544

1–3 years

5,688

4–7 years

4,956

8–11 years

3,166

12+ years

856

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 digestive tract disorder in dogs?: 16,532 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 148 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).

Digestive tract disorder with similar medicines

Digestive tract disorder after Milbemycin Oxime + Spinosad (Trifexis) 487 reports · 0.4% of its reports
Digestive tract disorder after Moxidectin (ProHeart 6) 88 reports · 0.2% of its reports
Digestive tract disorder after Milbemycin Oxime + Praziquantel (Interceptor Plus) 123 reports · 0.4% of its reports
Digestive tract disorder after Milbemycin Oxime (Interceptor) 178 reports · 0.6% of its reports
Digestive tract disorder after Selamectin (Revolution) 75 reports · 0.3% of its reports
Digestive tract disorder after Ivermectin (Heartgard) 63 reports · 0.5% of its reports
Digestive tract disorder after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 61 reports · 0.7% of its reports

All reported side effects of Ivermectin + Pyrantel in dogs · Medicines most reported with digestive tract disorder