Fever after Ivermectin + Pyrantel (Heartgard Plus) in dogs

597 reports to the FDA describe fever in dogs given Ivermectin + Pyrantel. That is 0.4% of all reports for this medicine, compared with 1.4% across reports for all dog medicines, so it is reported less often than average with this medicine.

597Reports

54%Marked serious

19%Recovered

15%Died or euthanised

8 daysTypical onset

How soon it started

Same day

52 20%

1–2 days

51 19%

3–7 days

27 10%

1–4 weeks

49 19%

Over a month

84 32%

How the animals did

Recovered

106 18%

Recovered with lasting effects

7 1.2%

Still unwell when reported

99 17%

Died

39 6.5%

Euthanised

51 8.5%

Not known

295 49%

Problems reported at the same time

312 52%

230 39%

173 29%

113 19%

86 14%

85 14%

79 13%

71 12%

Age of the animals

Under 1 year

121

1–3 years

180

4–7 years

143

8–11 years

100

12+ years

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 fever in dogs?: 597 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 8 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).

Fever with similar medicines

Fever after Milbemycin Oxime + Spinosad (Trifexis) 881 reports · 0.7% of its reports
Fever after Moxidectin (ProHeart 6) 1,914 reports · 3.8% of its reports
Fever after Milbemycin Oxime + Praziquantel (Interceptor Plus) 194 reports · 0.6% of its reports
Fever after Milbemycin Oxime (Interceptor) 255 reports · 0.9% of its reports
Fever after Selamectin (Revolution) 322 reports · 1.1% of its reports
Fever after Ivermectin (Heartgard) 154 reports · 1.3% of its reports
Fever after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 33 reports · 0.4% of its reports
Fever after Moxidectin + Pyrantel + Sarolaner (Simparica Trio) 20 reports · 1.7% of its reports

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