Breathing problems after Fipronil + S-methoprene (Frontline Plus) in dogs

The FDA has received 132 reports of breathing problems in dogs after Fipronil + S-methoprene. That is 4.5% of all reports for this medicine, compared with 2.7% across reports for all dog medicines, so it is reported unusually often with this medicine.

132Reports
66%Marked serious
45%Recovered
11%Died or euthanised
22 daysTypical onset
SponsoredWorried about your pet? Ask a veterinarian online, 24/7

How soon it started

Same day
14 18%
1–2 days
10 13%
3–7 days
6 7.9%
1–4 weeks
10 13%
Over a month
36 47%

How the animals did

Recovered
57 43%
Recovered with lasting effects
2 1.5%
Still unwell when reported
11 8.3%
Died
5 3.8%
Euthanised
9 6.8%
Not known
48 36%

Problems reported at the same time

Age of the animals

Under 1 year
13
1–3 years
35
4–7 years
25
8–11 years
37
12+ years
18

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 breathing problems in dogs?
132 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 22 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).

Breathing problems with similar medicines

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