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My cat's flea medicine isn't working. Should I use a flea collar?

Updated on September 23rd, 2025

Pet's info: Cat | Mixed Breed | Male | neutered | 3 years and 2 months old

We put a flea medication on our cats that didn’t do anything at all and a few weeks later got advantage. The fleas aren’t dying and we were looking at getting a flea collar. Do we need to wait until next month to do this?

2 Answers

Most Helpful Answer

Answered By Jennifer Summerfield, DVM CPDT-KA

Veterinarian, Certified Dog Trainer

Published on July 18th, 2019

I'm sorry to hear you've had trouble finding an effective flea med! Most over-the-counter options are not very effective in my experience, including Advantage - although it's probably the best of the currently available OTC options! Flea collars do not work well, and can often be toxic to cats.

Instead, I would recommend getting a prescription flea medication like Revolution or Bravecto from your veterinarian. This will be safe for your kitty, and much more effective. If it's been at least 1-2 weeks since you applied the Advantage, it should be safe to go ahead and use a new medication from your vet.

1Pet Parents found this answer helpful

Related Answers from Veterinarians

Answered By Jennifer Summerfield, DVM CPDT-KA
Veterinarian, Certified Dog Trainer
Published on July 18th, 2017
Advantage is generally a pretty effective flea medication for cats, so I'm surprised to hear that it hasn't been working well for Lily. If you want to try a different medication for her, I would suggest Revolution - I usually see good results with it for flea control, and it also prevents heartworms and intestinal parasites. As long as it's been at least two weeks since you applied the Advantage, it should be fine to go ahead and apply a dose of Revolution. I don't generally recommend flea collars for cats, as they tend not to work very well and can often be toxic for them.

You may also want to use a flea spray such as Knock-Out to treat your house and yard, as it's possible that Lily is continuing to pick up fleas from the environment - this can make it much more difficult for any flea medication to work correctly.
1Pet Parents found this answer helpful

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My cat has fleas. How long to wait between Hartz and Advantage II?

Fleas collars do not typically work well. Hartz is not as strong as most other flea medicines and tend to have the most reactions. Advantage is great one that is monthly, Bravecto is another great one and it will last for 3 months but requiers a prescription. I would wait at least 2 weeks in between the topicals for her safety and the flea collar does not matter for timing of products.

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My cat's flea treatment isn't working. Can I switch brands safely?

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Updated on September 23rd, 2025

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My cat still has fleas after Advantage. What flea treatment can I use?

Thanks for using Petco Pet Education Center, formerly Petcoach! Yes, you may in about 5-6 days. However, I would highly recommend you use a stronger and likely more efficacious product. There are plenty of flea products in the market and a lot of them are very effective. I prefer Bravecto and Frontline plus. You can pick one of those products. The nice thing about Bravecto is that it is very effective and it is only applied once every 3 months. You can also use a product called Capstar along with one of the previously mentioned products which can help kill a lot of fleas at once. Remember to vacuum all the surfaces that have contact with your pup regularly. This is very likely going to work well. Good luck and have a great day!

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My cat's flea treatment failed. What to do while waiting for new meds?

If you want an effective product please use one of newer ones like Cheristin. I don't think you will get any better results with Advantage. It is recommended to wait a minimum of 3 weeks between product applications. https://worldtails.securevetsource.com/itemView/view/198944_HomeDelivery.pml?productId=115569 While you wait you can get Capstar and give him that every couple days if need be. One pill lasts 24 hours but will kill everything on him. https://www.petco.com/shop/en/petcostore/product/capstar-flea-tablets-for-cats-2-25-lbs You also need to treat the house or the fleas will keep getting on him. I recommend Knockout Spray ES: https://www.chewy.com/virbac-knockout-es-area-treatment/dp/53856

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My dog has fleas. Are flea collars effective, or are oral meds better?

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My cat has fleas, Seresto collar stopped. What's the best treatment?

Fleas can be frustrating to treat. I know that many people have a lot of success with Seresto collars, but I have not. In order to treat Bandit’s fleas, I recommend using a good quality topical product, such as Advantage (use monthly) or Bravecto (prescription based and used every 3 months). Flea shampoos are rarely effective and can cause irritation to the skin, so I tend to steer clear of them. Be sure to vacuum daily, dispose of the vacuum bag frequently, and wash Bandit’s bedding in hot water. Continue to apply flea medication regularly in order to disrupt the fleas’ life cycle to prevent a recurrence. I hope this helps and that all goes well for Bandit!

Updated on September 23rd, 2025

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