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Ask the Vet: The Best Flea and Tick Medicine for Cats

Est. read time: 8 min.

Whether your cat is indoor or outdoor, you need to keep your cat safe from fleas (Ctenocephalides felis) and ticks. In this post, we’ll cover the best options for flea and tick medicine for cats.

What if my cat is indoor-only?

A lot of you are thinking, “Well, my cat is indoors. I don’t need flea and tick medication.” But you might. If your cat is indoor-only on the 38th floor of your apartment building in New York City, no, you don’t. But if you have anyone else in the household who goes outside, you must!

As a veterinarian, my indoor cat is on flea and tick medication—yup, that’s right. And read on to find out why…

When it comes to fleas and ticks, these external parasites are not only annoying to your cat, but they can result in secondary life-threatening infections. 

Fleas and ticks can result in a whole host of problems, including:

  • Tapeworms: Little secret here. If your cat comes in with rice-like segments around the perineal region, we know your cat has a flea problem. We’re not just trying to sell you flea medication for fun. That’s because cats typically become infected with tapeworms after they have eaten an infected flea while grooming or by eating infected flea-ridden rodents.
  • Discomfort and pain from itching.
  • Flea-allergic dermatitis: That’s when your cat has severe allergies from the saliva of a flea, resulting in excessive grooming, hair loss, and red, raised, crusty bumps all over the body—it’s torturous to your cat, as this allergy is excruciatingly uncomfortable.
  • Life-threatening anemia: This is more common in young pediatric kittens, and occurs from the fleas sucking out over ½ to ¾ of your kitten’s blood supply!
  • Tick-transmitted diseases like Lyme disease: Yes, while rare, cats can get infected with Borrelia, but rarely get as sick as dogs from it!
  • Hemobartonellosis: A bacterial parasite that attacks your cat’s red blood cells.
  • Cytauxzoonosis (also known as bobcat fever): Causes severe fever, anemia, breathing difficulties, and is almost always fatal.
  • Tularemia: An uncommon but deadly bacterial infection that causes enlarged lymph nodes, abscesses, fever, weight loss, and loss of appetite.
  • Plague (Yersinia pestis): Can cause enlarged lymph nodes, lethargy, sepsis, and shock.
  • And more tick-related infections like ehrlichiosis and babeseosis!

Another reason why you want to prevent any type of flea and tick infestation in your cat? 

Because fleas replicate. A lot. One female flea can lay anywhere from 20-50 eggs a day, with half of those hatching into female fleas. This eventually can produce up to 20,000 new adult fleas in less than 2 months. Which means it’s then very, very hard to get rid of the infestation in your house. And then they can bite you and your two-legged family members also! Getting rid of a flea infestation in the house is a full-time job! It requires meticulous vacuuming of the carpet, rugs, and furniture EVERY. SINGLE. DAY for weeks at a time, and changing or dumping out the vacuum bag immediately after. Yup, you heard me right. EVERY. SINGLE. DAY for weeks at a time. Infestations often require a professional exterminator to “bomb” your house, in addition to powders, topical anti-flea medications, sprays, and more. 

So, why do I keep my indoor cat on flea and tick medication? 

While my cat stays inside, my dog goes outside into my fenced-in backyard. And we have mice, gophers, rabbits, and other wildlife in the backyard, which can seed our backyard with fleas and other parasites. While my dog is also on a fast-acting flea and tick medication all spring and summer, your four-legged family member can bring one or two fleas inside. If the external parasites aren’t killed quickly with a prescription-strength flea and tick medication, you’ll suddenly have thousands of fleas within your house within days to weeks. Not worth the risk!

Also, a lot of people think that fleas and ticks will die off in the cold. (Trust me, I know cold—I live in Minnesota, and we have long winters here.) Yes, that is true, but depending on how long the cold freeze is for, they may just go dormant. But they can live for a long time comfortably inside your house, since it’ll be much more temperate.

The good news? There is a lot of really effective, safe flea and tick medicine for cats out there now. But you need to know which ones to use, how long to use them for, what the weight and age of your cat is, and how to use them appropriately. 

Which flea and tick medicine for cats should I use?

As a heads up, essential oils, boric acid, diatomaceous earth, and all the other Internet remedies don’t work well for infestations and may not be safe for use in cats. I don’t like over-the-counter flea and tick collars, as they aren’t strong enough (and only keep fleas away from your cat’s neck region). 

When it comes to the best flea and tick medicine for cats, I only recommend using prescription-strength veterinary products—that’s what I use on my own cat. I don’t care which one you use, but I prefer a topical one applied to the back of my cat’s neck (my cat is hard to pill!). 

I also prefer one that will simultaneously prevent heartworm disease in my cat, too, if possible. Common brand names include Revolution Plus™ and Bravecto Plus™. I also love Capstar™ for a really quick kill of fleas in the acute setting (so if you just found a cat and want to bring it into your house, get this from your vet first!). 

Keep in mind that you should never use products containing high-concentration pyrethrins or pyrethroids, as they are very poisonous to cats. 

How long should I use flea and tick medication on my cat?

When in doubt, I use external parasite prevention as soon as the temperature warms up above freezing. (In Minnesota, this is typically in late March or early April.) I use it until there is a consistent hard frost for weeks at a time. (In Minnesota, this is typically in October/November.) If you live in more temperate regions (e.g., Texas, the South, Pacific Northwest, etc.), you should use it year-round. Because trust me, in the long run, it’ll be cheaper—and safer for your cat—than getting a flea infestation or horrible tick-borne infection. When using flea and tick medicine for cats, make sure to read the instructions carefully—most of these products last one month, although a few last 2 months.

How to use flea and tick medicine for cats appropriately

Please know that prescription flea and tick medications are very safe for our pets—they are extensively tested and regulated by the Environmental Protection Agency (EPA) or Food & Drug Administration (FDA) in the United States. 

Rarely, I have seen problems when pet parents give flea and tick medications, and typically, it’s because of user error. It’s not knowing the correct age or weight of your cat. Take time to read the whole box and instructions prior to applying the medication on your cat. (There’s also a huge, detailed pamphlet in the container that you can read for more information). 

More importantly, never use a flea and tick medication meant for a dog on a cat. As an emergency critical care specialist, I see a lot of accidental pyrethrin and pyrethroid poisoning in cats; this occurs when a well-intentioned pet parent applies a concentrated “small dog” flea and tick product onto their “big” cat. While topical flea and tick spot-on products are safe for dogs, they are very dangerous for cats. 

Due to a cat’s altered liver metabolism, cats are significantly more sensitive to pyrethroids than dogs. While an exact toxic dose for cats isn’t known, it’s estimated that concentrations greater than 5-10% of pyrethrins or pyrethroids may lead to signs of tremoring, hyperthermia, seizuring, and death without treatment. 

When in doubt, please keep your cat safe from the pesky-to-deadly problems of fleas and ticks. It’s more common of a problem than you think, and with all the safe preventatives out there nowadays, there’s no excuse for seeing fleas, ticks, or flea dirt—what looks like ground black pepper specks (and is actually a blood meal and flea waste product)—on your furry family member! Please consult your veterinarian to pick the right flea and tick medicine for cats in your household.

Cover photo by Sheri Hooley on Unsplash

Grey tabby cat with a collar in the grass - the best flea and tick medicine for cats


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