Cat's flea treatment not working. Can I safely apply Frontline now?
Updated On September 23rd, 2025
Pet's info: Cat | Domestic Longhair | Female | spayed | 10 lbs
I place Sentry Plus flea medication on my cats last Wednesday. The medicine does not seem to be working. Can I safely use Frontline now or do I need to wait one month to apply it?
2 Answers
Most Helpful Answer
Published on October 2nd, 2017
Since both Sentry and Frontline use the same active ingredient (fipronil) it is unlikely that you will see better protection switching to the Frontline. You will need to choose a product with a different ingredient, like Advantage or Revolution or a Seresto collar. If you choose to use another topical, I would recommend bathing your kitty today to remove any remnants of the Sentry, and wait 3 days to apply the next topical. It is important to wait after bathing so that the natural body oils have time to coat the skin to ensure adequate absorption. You do not need to wait or bathe to use a Seresto collar.
1Pet Parents found this answer helpful
Related Answers from Veterinarians
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Published on May 13th, 2019
I would wait until the skin reaction from the collar has completely healed before putting another topical medication on the skin. I would recommend asking your vet if you can give a dose of Comfortis this month. It is an oral flea prevention so you won’t have to worry about the skin at all. I hope this helps. Thanks for using Petco Pet Education Center, formerly Petcoach. Best of luck.
1Pet Parents found this answer helpful
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