Reddening of the skin after Ivermectin + Pyrantel (Heartgard Plus) in dogs

The FDA has received 173 reports of reddening of the skin in dogs after Ivermectin + Pyrantel. That is 0.1% of all reports for this medicine, compared with 0.4% across reports for all dog medicines, so it is reported less often than average with this medicine.

173Reports

42%Marked serious

38%Recovered

1.7%Died or euthanised

3 daysTypical onset

How soon it started

Same day

29 25%

1–2 days

27 24%

3–7 days

7 6.1%

1–4 weeks

12 11%

Over a month

39 34%

How the animals did

Recovered

57 33%

Recovered with lasting effects

9 5.2%

Still unwell when reported

19 11%

Died

1 0.6%

Euthanised

2 1.2%

Not known

85 49%

Problems reported at the same time

85 49%

29 17%

27 16%

26 15%

21 12%

19 11%

Skin rash or irritation

18 10%

Breathing problems

12 6.9%

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 reddening of the skin in dogs?: 173 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 3 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).

Reddening of the skin with similar medicines

Reddening of the skin after Milbemycin Oxime + Spinosad (Trifexis) 729 reports · 0.6% of its reports
Reddening of the skin after Moxidectin (ProHeart 6) 485 reports · 1.0% of its reports
Reddening of the skin after Milbemycin Oxime + Praziquantel (Interceptor Plus) 101 reports · 0.3% of its reports
Reddening of the skin after Selamectin (Revolution) 51 reports · 0.2% of its reports
Reddening of the skin after Ivermectin (Heartgard) 32 reports · 0.3% of its reports

All reported side effects of Ivermectin + Pyrantel in dogs · Medicines most reported with reddening of the skin