How Long Do Flea and Tick Medications Take to Work on Cats?

Barri J. Morrison, DVM
By Barri J. Morrison, DVM on Jul. 14, 2022
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Fleas and Ticks on Cats

Fleas and ticks are two of the most common parasites affecting cats. These parasites hitch a ride into your home on your cat, on other pets, or even on uninvited guests like rodents. While outdoor cats will encounter fleas daily, your indoor cat is just as susceptible.

When treating your cat, you may wonder how long until the medication kicks in. The answer depends on the medication and the type of parasite. For example, fleas tend to die more quickly than ticks.

If you see a tick on your cat, it is important to see a veterinarian regardless of whether the tick is alive or dead to ensure the tick’s head and mouth parts are removed properly. Ticks can transmit serious diseases such as Lyme disease and Cytauxzoonosis, which can be fatal if not treated.

It is extremely important to provide flea and tick prevention regularly for all cats, indoors and outdoors, and to recognize the signs of flea or ticks.

Types of Flea and Tick Medication for Cats

While there are many safe, effective medications available to control fleas and ticks, they may not be effective in some cats due to resistance or toxicity risks. The most popular medications to combat fleas and ticks are topical, meaning those that go directly onto the skin. Most oral medications only help control fleas and do not provide tick coverage.

The following medications, and how they are applied, can be used for both fleas and ticks:

Topical Flea & Tick Medication

Oral Flea & Tick Medication

Oral Flea-only Medication

Collar Flea & Tick Medication

Topical preventions have been shown to clear fleas on cats within 12-48 hours, and oral preventions often work within the first 2-4 hours.

Never use a flea or tick medication labeled for dogs. They are not interchangeable, and a product made for dogs can make cats extremely sick, and in rare cases it may be fatal.

Signs Flea and Tick Medication are Working

It can take up to 24 hours for fleas on your cat to die, although it might occur much quicker. Fleas typically die faster than ticks, since they are a much less robust parasite. Ticks can take up to 48 hours for treatment to work.

Oral flea medications tend to work a bit faster in cats than topical medications. However, most oral medications lack tick coverage. If your cat has a severe flea problem, several rounds of treatment over several months will be needed to eliminate the problem, because the life cycle of the flea is about 3 months.

Not all dead ticks will fall off your cat. If you see a live or dead tick, take your cat to the veterinarian to have it removed properly to make sure the head and mouth parts are entirely removed. This is important to prevent more serious infections, such as Lyme disease.

If you don’t see a decrease in the number of fleas and ticks, you might need to switch medications. Talk with your veterinarian to help you choose the next step regarding medication and dosage. Do not simply increase the dosage without first consulting your vet.  

Other Treatments to Help with Fleas and Ticks

Other treatments can also help to kill fleas and ticks on your cat, including:

  • A bath with special medication shampoo (flea shampoo) and warm water

  • A flea comb to remove fleas from your cats while waiting for medication to work effectively

  • Flea/tick wipes, creams, sprays

Please ensure that any treatment you choose for your cat is made specifically for cats. Dog preventions and treatments should never be used on cats, as they can contain ingredients that are safe for dogs but potentially fatal to cats. While other treatments are helpful, they are best when combined with a traditional flea and tick treatment such as a topical or oral preventative. Make sure the method of treatment you choose for your cat’s flea treatment is approved by your veterinarian.

When Will Symptoms Start to Decrease?

  • Topical flea and tick treatments such as Revolution Plus kill fleas and ticks within 12 hours of application, and at least 98% of fleas are killed within 24 hours.

  • Oral medications such as Capstar begin to kill fleas within 30 minutes, and continue to rapidly control fleas for 24 hours.

  • The Seresto flea collar for cats works within 24 hours, and the fleas do not even need to bite your cat to be killed.

As these medications start working, you will notice a decrease in your cat’s scratching, and you may also notice more fleas. This is because you are seeing the fleas and/or ticks die off and come out from hiding under your cat’s coat. If your cat has a skin infection or irritation in the form of red spots or scabs from the parasites or from the scratching, these can take some time to heal. You may need antibiotics to fully heal the skin infections.

If you do not see an improvement of your cat’s flea and/or tick issue within 24 hours or at any time your cat seems to not be acting like herself, contact your veterinarian as soon as possible. 

How to Get Rid of Fleas and Ticks in Home

To effectively get rid of a flea and/or tick infestation, you must do more than just administer the medication to your cat. It is equally as important to treat the home, so the issue does not return. It’s best to do this while treating your cat, as well as to quarantine him in a small crate or tiled bathroom as you clean.

If you are cleaning your home yourself, remember to empty your vacuum bag outdoors immediately after use, as there still might be some live fleas or ticks inside. If a pest control company is not an option, it would be best to ask your veterinarian what is safe to be used at home, such as sprays, flea bombs, or powders.

Featured Image:

Barri J. Morrison, DVM


Barri J. Morrison, DVM


Barri Morrison was born and raised and currently resides in Ft. Lauderdale, Florida. She went to University of Florida for her...

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