General illness after Ivermectin + Pyrantel (Heartgard Plus) in dogs

127 reports to the FDA describe general illness in dogs given Ivermectin + Pyrantel. That is 0.1% of all reports for this medicine, compared with 0.2% across reports for all dog medicines, so it is reported less often than average with this medicine.

127Reports
71%Marked serious
28%Recovered
23%Died or euthanised
21 daysTypical onset
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How soon it started

Same day
14 20%
1–2 days
9 13%
3–7 days
2 2.9%
1–4 weeks
18 26%
Over a month
26 38%

How the animals did

Recovered
23 18%
Recovered with lasting effects
13 10%
Still unwell when reported
7 5.5%
Died
14 11%
Euthanised
15 12%
Not known
55 43%

Problems reported at the same time

Age of the animals

Under 1 year
10
1–3 years
32
4–7 years
26
8–11 years
21
12+ years
13

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 general illness in dogs?
127 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 21 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).

General illness with similar medicines

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