Dehydration after Ivermectin + Pyrantel (Heartgard Plus) in dogs

The FDA has received 322 reports of dehydration in dogs after Ivermectin + Pyrantel. That is 0.2% of all reports for this medicine, compared with 0.7% across reports for all dog medicines, so it is reported less often than average with this medicine.

322Reports

58%Marked serious

22%Recovered

14%Died or euthanised

2 daysTypical onset

How soon it started

Same day

50 28%

1–2 days

45 25%

3–7 days

13 7.3%

1–4 weeks

24 13%

Over a month

46 26%

How the animals did

Recovered

65 20%

Recovered with lasting effects

6 1.9%

Still unwell when reported

54 17%

Died

21 6.5%

Euthanised

24 7.5%

Not known

152 47%

Problems reported at the same time

205 64%

166 52%

156 48%

147 46%

90 28%

46 14%

44 14%

35 11%

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). 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 dehydration in dogs?: 322 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 2 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).

Dehydration with similar medicines

Dehydration after Milbemycin Oxime + Spinosad (Trifexis) 624 reports · 0.5% of its reports
Dehydration after Moxidectin (ProHeart 6) 408 reports · 0.8% of its reports
Dehydration after Milbemycin Oxime + Praziquantel (Interceptor Plus) 133 reports · 0.4% of its reports
Dehydration after Milbemycin Oxime (Interceptor) 135 reports · 0.5% of its reports
Dehydration after Selamectin (Revolution) 106 reports · 0.4% of its reports
Dehydration after Ivermectin (Heartgard) 93 reports · 0.8% of its reports
Dehydration after Ivermectin + Praziquantel + Pyrantel (Iverhart Max) 32 reports · 0.4% of its reports

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