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My cat still has fleas after treatment. How soon can I reapply?

Updated on September 23rd, 2025

Pet's info: Cat | Domestic Shorthair | Female | spayed | 3 years and 8 months old | 8 lbs

I gave my cat her flea treatment on 12/31 (sentry) and over the holidays she was exposed to fleas. I bough a new flea treatment (soresto) how soon can I put that on her? I've been using a flea comb on her mulitple times a day and pulling off as many as she will sit still for but she is suffering and scratching all day and night. I don't want to over do it and cause a reaction but the other flea treatment isn't working.

2 Answers

Most Helpful Answer

Lindsey Edwards MVB, BSc, IVCA

Answered By Lindsey Edwards MVB, BSc, IVCA

Veterinarian

Published on January 8th, 2018

Generally flea products should not be reapplied within 2-4weeks. Many flea products (including sentry) only kill adult fleas after they bite your pet so there can be a timeframe in between where you may see the adult flea before it becomed unwell and dies. I strongly recommend you use an insecticidal household spray to kill any eggs and larvae in the house/bedding areas in such a severe infestation (5% of the fkea population is adult at any one stage; 95% are eggs and developing larvae). Seresto could then be applied after 14days
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Related Answers from Veterinarians

  • Published on October 9th, 2019

    I would recommend to wait at least two weeks in between treatments. Advantage or comfortis are both good products and will be effective on her.
    Often flea allergy dermatitis is noticed with presence of fleas. This should be ideally treated. Please discuss with your veterinarian this possibility and treatment option.

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    1Pet Parents found this answer helpful

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