Excessive thirst after Fipronil + S-methoprene (Frontline Plus) in dogs

23 reports to the FDA describe excessive thirst in dogs given Fipronil + S-methoprene. That is 0.8% 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.

23Reports

48%Marked serious

52%Recovered

13%Died or euthanised

14 daysTypical onset

How soon it started

Same day

3 23%

1–2 days

1 7.7%

3–7 days

0 0.0%

1–4 weeks

5 38%

Over a month

4 31%

How the animals did

Recovered

12 52%

Still unwell when reported

4 17%

Died

2 8.7%

Euthanised

1 4.3%

Not known

4 17%

Problems reported at the same time

Excessive urination

14 61%

9 39%

7 30%

7 30%

5 22%

4 17%

4 17%

3 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 excessive thirst in dogs?: 23 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 14 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).

Excessive thirst with similar medicines

Excessive thirst after Spinosad (Comfortis) 374 reports · 0.7% of its reports
Excessive thirst after Lufenuron + Milbemycin Oxime (Sentinel) 131 reports · 0.5% of its reports
Excessive thirst after Imidacloprid + Moxidectin (Advantage Multi) 114 reports · 0.9% of its reports
Excessive thirst after Nitenpyram (Capstar) 50 reports · 0.5% of its reports
Excessive thirst after Flumethrin + Imidacloprid (Seresto) 21 reports · 0.9% of its reports
Excessive thirst after Fipronil 23 reports · 1.6% of its reports

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