Behaviour change after Fipronil + S-methoprene (Frontline Plus) in cats

23 reports to the FDA describe behaviour change in cats given Fipronil + S-methoprene. That is 6.3% of all reports for this medicine, compared with 5.4% across reports for all cat medicines.

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How soon it started

How the animals did

Problems reported at the same time

Age of the animals

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 behaviour change in cats?

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 5 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).

Behaviour change with similar medicines

• Behaviour change after Spinosad (Comfortis) 359 reports · 3.1% of its reports
• Behaviour change after Nitenpyram (Capstar) 564 reports · 6.5% of its reports
• Behaviour change after Imidacloprid + Moxidectin (Advantage Multi) 1,057 reports · 13% of its reports
• Behaviour change after Lufenuron 24 reports · 2.2% of its reports
• Behaviour change after Flumethrin + Imidacloprid (Seresto) 68 reports · 10% of its reports
• Behaviour change after Imidacloprid + Pyriproxyfen 80 reports · 12% of its reports
• Behaviour change after Imidacloprid 26 reports · 10% of its reports

All reported side effects of Fipronil + S-methoprene in cats · Medicines most reported with behaviour change