Skin redness after Fipronil + S-methoprene (Frontline Plus) in dogs

47 reports to the FDA describe skin redness in dogs given Fipronil + S-methoprene. That is 1.6% of all reports for this medicine, compared with 1.0% across reports for all dog medicines, so it is reported unusually often with this medicine.

47Reports

70%Marked serious

34%Recovered

2.1%Died or euthanised

29 daysTypical onset

How soon it started

Same day

3 12%

1–2 days

3 12%

3–7 days

5 19%

1–4 weeks

3 12%

Over a month

12 46%

How the animals did

Recovered

15 32%

Recovered with lasting effects

1 2.1%

Still unwell when reported

5 11%

Died

1 2.1%

Not known

25 53%

Problems reported at the same time

Itching

15 32%

Hair loss

11 23%

Vomiting

9 19%

Application site reaction

8 17%

Loss of appetite

7 15%

Skin rash or irritation

7 15%

Breathing problems

7 15%

Fever

6 13%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Fipronil kills fleas and ticks (spot-on).

Products with this combination include Frontline Plus. The FDA hides brand names in its public data, so these reports cover every product with the same active ingredients.

Questions owners ask

Can Fipronil + S-methoprene cause skin redness in dogs?: 47 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 29 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).

Skin redness with similar medicines

Skin redness after Spinosad (Comfortis) 266 reports · 0.5% of its reports
Skin redness after Lufenuron + Milbemycin Oxime (Sentinel) 119 reports · 0.5% of its reports
Skin redness after Imidacloprid + Moxidectin (Advantage Multi) 470 reports · 3.6% of its reports
Skin redness after Nitenpyram (Capstar) 102 reports · 0.9% of its reports
Skin redness after Lufenuron + Milbemycin Oxime + Praziquantel (Sentinel Spectrum) 41 reports · 0.4% of its reports
Skin redness after Flumethrin + Imidacloprid (Seresto) 101 reports · 4.4% of its reports
Skin redness after Imidacloprid 29 reports · 1.5% of its reports
Skin redness after Fipronil 25 reports · 1.8% of its reports
Skin redness after Imidacloprid + Permethrin + Pyriproxyfen 33 reports · 4.5% of its reports

All reported side effects of Fipronil + S-methoprene in dogs · Medicines most reported with skin redness