Blood in stool after Ivermectin (Heartgard) in dogs

31 reports to the FDA describe blood in stool in dogs given Ivermectin. That is 0.3% of all reports for this medicine, compared with 0.6% across reports for all dog medicines, so it is reported less often than average with this medicine.

31Reports

39%Marked serious

6.5%Recovered

26%Died or euthanised

31 daysTypical onset

How soon it started

Same day

5 33%

1–2 days

0 0.0%

3–7 days

1 6.7%

1–4 weeks

1 6.7%

Over a month

8 53%

How the animals did

Recovered

2 6.5%

Still unwell when reported

9 29%

Died

4 13%

Euthanised

4 13%

Not known

12 39%

Problems reported at the same time

16 52%

12 39%

11 35%

9 29%

8 26%

6 19%

6 19%

5 16%

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).

Products with this ingredient include Heartgard. 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 cause blood in stool in dogs?: 31 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 31 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).

Blood in stool with similar medicines

Blood in stool after Ivermectin + Pyrantel (Heartgard Plus) 196 reports · 0.1% of its reports
Blood in stool after Milbemycin Oxime + Spinosad (Trifexis) 79 reports · 0.1% of its reports
Blood in stool after Moxidectin (ProHeart 6) 185 reports · 0.4% of its reports
Blood in stool after Milbemycin Oxime + Praziquantel (Interceptor Plus) 38 reports · 0.1% of its reports
Blood in stool after Milbemycin Oxime (Interceptor) 148 reports · 0.5% of its reports
Blood in stool after Selamectin (Revolution) 109 reports · 0.4% of its reports

All reported side effects of Ivermectin in dogs · Medicines most reported with blood in stool