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My cat has fleas! What should I do?

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My cat has fleas! What should I do?


cat with fleas

Maybe your cat won’t stop scratching. Or maybe, while parting your cat’s fur, you thought you saw something scurry by. Or maybe you noticed an odd bit of dirt on your white tile floor where your normally immaculate kitty had just been lying.


And you think your cat might have fleas.


You’re right to be concerned. As small as they are, fleas aren’t just a little problem. One itty bitty flea can turn into a monster swarm of 20,000 fleas in just 60 days, infesting your carpeting and your sofa, and biting your ankles until they are covered in itchy red bumps.


Fleas aren’t “just fleas” to cats either. The bites can drive a cat absolutely mad with irritation, and a serious infestation can be life-threatening to a young kitten, an older cat, or one with other health problems.


cat with fleas

Fleas carry diseases and parasites of their own, too, that can infect both humans and cats. It is important to take a flea problem seriously, and to begin treatment as soon as you suspect there is a problem.


The best way to treat a flea problem is to prevent it from ever starting. We’ll talk about flea prevention in this post, too.


But first, let’s talk about the life of a flea. It helps to understand how fleas live and behave if you want to understand how treatment and prevention really works.


What is a flea?



A flea is a tiny brownish insect, about an 1/8th of an inch long, that makes its living by sucking the blood of mammals and birds. They have strong claws that help them cling to their victims, and a three-part mouth that is perfectly designed for piercing skin and blood vessels, and slurping up blood.[1]


Fleas don’t have wings, but they have powerful hind legs that allow them to jump about 5 inches straight up and about 8 inches horizontally, although in one study of hungry cat fleas, one sprung 19 inches.[2] In other words, a motivated flea will find its way to your cat.


There are about 2,500 types of fleas in the world, but the one you should be mostly concerned about is Ctenocephalides felis felis: your typical cat flea. A cat’s warm, moist, furry skin are this flea’s favorite place to live.


The flea life cycle



Fleas go through a couple of stages between egg and adult, much like butterflies (but yuckier). An adult female flea living on your cat will start the cycle by mating and laying eggs. She’ll drink some blood, lay some eggs, drink some more blood, lay some more eggs, and so on. A female flea can lay thousands of eggs in her short life.


The eggs hatch into larvae, which, like caterpillars, spin cocoons. The pupae within the cocoon matures, and when conditions are just right, an adult flea pops out of the cocoon to start the cycle all over.



Under the best of conditions, a flea can complete its entire lifecycle in just two weeks. If things in the outside world aren’t just right for the developing pupae, however, it can lie dormant for up to a year, waiting for the right conditions to hatch. A just-hatched flea will jump onto its victim, drink some blood, and, if she’s a female, begin laying her own eggs in just two days’ time.[3]


Why you should worry about fleas


Fleas are a very common problem for cat guardians. But they can also be a very serious problem. Here’s why:


Fleas can suck too much blood. A single adult flea eats many times its own weight in blood in its lifetime. If your cat is a normal, healthy adult, and the flea infestation isn’t too severe, the blood loss is unlikely to become life threatening. But if a kitten has fleas, or if your cat's a senior, or is suffering from another health problem, flea bites can be devastating.
“Flea-bite anemia” is the veterinary term for what occurs when a cat has lost too much blood to fleas. A kitten, for example, with a severe infestation, may not have enough healthy red blood cells to carry oxygen to all of her body parts.
If not treated, flea-bite anemia can be fatal. A cat with this problem may need to be hospitalized for blood transfusions and iron supplementation to try to reverse the damage caused by fleas.[4]
cat with fleas
Some cats are allergic to fleas. Some cats are hardly bothered by fleas. But for cats who are allergic to fleas, they can be driven absolutely wild by the intense itching caused by the bites from even a single one of these parasites.
Cats who are allergic to fleas are actually allergic to their saliva. When a flea bites, it leaves behind a little bit of flea spit in the tiny wound. An allergic cat’s body may respond very severely to the proteins in that saliva causing itching that can last for days.
The result is a condition called flea-bite dermatitis. Your cat might be covered in red, crusty, scabby bumps, especially on the lower back, thighs, belly, head, and neck.[5] There may be hair loss and infection, especially where your cat has been scratching with sharp claws in an effort to get some relief.
(You might want to read, “Why does my cat shed so much?” and "Feline hyperesthesia syndrome")
Fleas carry parasites of their own. Any cat with fleas is likely to also have a tapeworm infection.[6]
 A tapeworm is the stuff of nightmares. This intestinal parasite hooks itself into the wall of your cat’s guts with its mouth, growing up to 11 inches long while it feeds off of the food you intended to feed your cat.[7]
Tapeworms need fleas to complete their lifecycle. A flea larva will eat a tapeworm egg, and a grooming cat will inadvertently eat the flea larva containing that developing tapeworm.
Tapeworms can cause diarrhea, weight loss, and vomiting. Your cat may be hungrier, and his coat may start to look scruffier as the parasite consumes all the important nutrients in his food.[8]
Fleas carry bacteria that can harm humans. Fleas carry a bacteria called Bartonella henselae. Cats can become infected with B. henselae by eating flea poop when they groom, or when flea poop on the skin comes in contact with an open wound. The resulting infection is called Bartonellosis.
While cats don’t appear to become immediately ill from Bartonellosis, it’s been linked to mouth and gum disease, eye inflammation, and heart disease.[9] Cats seem to be able to carry this disease in their bodies for more than a year.


B. henselae can cause serious illness in humans. We can contract “cat-scratch fever” when a cat with flea poop in her claws or mouth scratches or bites us. Bartonella can cause fever, nausea, headache, fatigue, and swollen glands. In rare cases, it can cause neurological problems, or affect a person’s bones, joints, eyes, heart, or other organs.[10]
Read about what you should do if you're bitten or scratched by a cat in this post.


How do I know if my cat has fleas?


If you suspect your cat has fleas, look for these signs:

cat scratching 

Intense scratching or biting. Fleas make your cat’s skin itchy, and cats with fleas may scratch, lick, bite, and chew their skin relentlessly in an effort to relieve their discomfort.


Excessive grooming. Some cats will groom themselves bald in spots in an effort to soothe themselves. Bald patches around the back of hind legs, neck, around the base of tail are not uncommon.


(For more information, read, “Excessive grooming in cats.”)


Restlessness or agitation. If your cat is growling, shaking his head, rubbing himself on the furniture or floor, or darting from one side of the room to the other, it could be fleas driving him crazy.

cat with fleas 

Red marks or scabs. If your cat is allergic to flea saliva (see above), red, inflamed or oozy skin, and crusty scabs could be a sign of flea-allergy dermatitis.


Hair loss. Patchy fur loss, especially near the base of the tail, neck, or hind legs are another sign of flea-allergy dermatitis, or a cat who is just being driven to distraction by biting fleas.


A cat who seems sick. If you have a kitten, or an elderly cat, or a cat that is experiencing some other health problems, who now has pale gums or muscle loss and seems weak, it could be a sign of flea-bite anemia (see above). Blood-sucking fleas could be depriving your cat of her own red blood cells.[11]


(Read, “How do you know if your cat is sick?”)

fleas on skin 

Dark specks on your cat’s fur. If you see pepper-like specks on your cat’s fur, especially on his neck or rump, or if you notice these specks on your comb or brush when grooming your cat, it’s probably flea poop, also known as “flea dirt.” How do you know for sure that it’s flea poop? Gather a few grains and sprinkle them on a wet paper towel. They’ll appear red as they dissolve because they are composed of digested blood.


Light-colored specks on your cat’s hair or bedding. These are likely flea eggs, soon to be biting adult fleas.


Red spots on your cat’s bed. Flea dirt that falls off onto your cats bedding will turn red due to moisture or warmth from your cat’s body.


Your cat is avoiding the carpeted areas of your home. Fleas like warm, dark places, such as your carpeting and furniture. Your cat may know that the torment from fleas increases in these areas of your home and may learn to avoid them.


Grains of “rice” around your cat’s anus. If you see what appears to be grains of rice at the end of your cat’s digestive tract, it’s likely egg packets from tapeworms in his intestines. Tapeworms are a sure sign that your cat is infected with fleas. When these egg packets dry up, they’ll crack and release hundreds of tapeworm eggs. Yuck![12]


Fleas. Seeing fleas – tiny, little brown insects – on your cat’s fur or bedding is the surest sign of all that your cat is infected.


What to do if your cat has fleas



If your cat has fleas, your house has fleas. Your yard likely has fleas, too. If you have other pets, they will have fleas as well. Any treatment plan has to address fleas on all four battlefronts.


Because fleas have a four-stage lifecycle, it can take up to eight months to attack every flea in every stage on every battlefront to completely eradicate them. This is what makes prevention so important. More on that in a minute.


How to treat your pets for fleas


Just because you’ve seen fleas on only one of your cats, doesn’t mean that they don’t all have fleas, and the dog, too. To successfully rid your cat of fleas, you will need to treat all of your cats and dogs (see below to find out which kind of dog treatments are safe to use when you have cats in the house.)


Call your vet before applying any products to your pets


It’s wise to make a call to your vet’s office at this point. There are many products on the market that all have different modes of action. We’ll discuss these in a little more detail below, but new products and new technologies are always emerging and your vet will have the most updated product information.


cat being treated for fleas

They’ll also know what products seem to be working best in your geographical area. While there has been no documentation of fleas becoming resistant to any of the new products on the market yet, it’s possible that it could happen. Also, there is natural variation in any species, even fleas, and some fleas in some areas may be more susceptible to one type of insecticide than another.[13]


And finally, if you have both dogs and cats in the house, your vet is the best person to help you choose the safest products to use. Products designed for dogs cannot be used on cats, and (generally speaking) vice versa. I’ve discussed this in more detail below, but many products intended for dogs can be lethal for cats who are just living in the same household with a treated dog. And products intended for cats are not necessarily the right dosage to effectively treat a dog.


Be sure to tell your vet about any flea-control products you may have already used, as it’s important to not combine insecticides with similar modes of action.


Grooming can reduce the flea load on your pets

 (*Note, as an Amazon and Associate, I earn from qualifying purchases.)


While you are waiting for the flea medicines to do their job, you can help ease your cat’s suffering by combing out fleas.


Use a fine-toothed metal comb, preferably one designed for flea removal, such as this inexpensive 4-piece set by Gnawrishing. Comb through your cat’s fur from head to tail several times a day to skim off adult fleas and their eggs. Dip the comb in hot water with a little liquid dishwashing soap as you go (rinsing the comb before returning it to your cat’s fur) to kill the fleas.[14]


How to treat your house for fleas



Ridding a home of fleas is not quick, it’s not simple, and it’s not easy. Everything you do on Day 1, you’re going to have to repeat, and repeat, and repeat until you’ve been successful.


Understand that it can take months to be rid of fleas in your home because of the fleas’ multi-stage lifecycle. Even if you manage to kill every adult flea in your house, there are still eggs waiting to hatch and pupae eager to open. You’ll have to be patient and very persistent.


Start by vacuuming the whole house. The “whole house” means the carpeting, of course, but also the hardwood floors and tiles (fleas can get into cracks in the floorboards and other crevices), the upholstered furniture (including the undersides), throw rugs, and curtains. Immediately throw the vacuum bag into a garbage bin outside to prevent flea eggs in the bag from hatching in your house.
Vacuum first, before anything else, because the vibrations from the vacuum cleaner will encourage fleas in the pupae stage to emerge. They can then be killed by insecticide.
Wash all pet beds and soft toys in hot, soapy water.
Wash all of your bedding, as well as bath mats, cushions, and throw pillows in hot water, too.
Contact a professional flea exterminator, or use a flea control spray, like this one by Petarmor, which kills not only adult fleas, but the eggs and larvae, too. (Do not apply sprays intended for the home directly on your pets).
Note that once fleas hatch, they move away from the light and burrow deep into carpets and other nooks and crannies. They can be difficult to reach. Move your furniture, move cushions, and spray underneath everything. Concentrate on baseboards, and cracks and crevices in the floor boards.

How to treat your yard for fleas

 spraying yard for fleas

Treat your lawn with insecticide such as Scotts Summerguard Lawn Food with Insect Control.
Spray the perimeter of your lawn to build a “wall” around your property to keep fleas out. Consider a product like Ortho Home Defense Insect Killer.
Keep your lawn mowed and dethatched. Fleas love to hide in long grass, and like laying eggs under a good thatch cover.
Prune and trim to allow as much light onto your property as possible. Fleas thrive in darkness.
Mulch with cedar if possible, especially in places where your cat likes to nap. Fleas do not like cedar.
Get rid of flea hiding spots. Clean up yard junk and clutter. Remove leaf piles, trash, and lumber – anything that looks like a good place to lay eggs to a flea.[15]


How to prevent your cat from getting fleas


You know how we say an ounce of prevention is worth a pound of cure?


Hopefully, you’ve read all the paragraphs that came before this one and you’re convinced you want to spare your cat and your human family the health risks that are associated with fleas. You’ve read our instructions for ridding your cat (and your household, yard, and other pets) of fleas and have decided that it’s something you never want to go through. This is where prevention comes in.


New technology in flea prevention


flea treatment on cat

Fleas have been a scourge for millennia, but you are lucky enough to live in today’s world of modern flea-control products.


As recently as the 1980s-1990s the only flea-control products that were available were old-style collars, shampoos, powders, and sprays that were only minimally effective. They were good at killing adult fleas at the moment of application, but had no real lasting effect, and did nothing for fleas in other stages of life. Many of these products are still available on supermarket shelves. These are not the products you want to use on your cat today.


New products attack fleas in various lifecycle stages


cat with fleas

Today’s flea-control products are completely different, thanks to the development of some 20 or more different flea control agents, which attack fleas at various stages in their lifecycle. The ones your vet will recommend will be FDA-approved as safe for cats.


Many need to be given or applied only once a month (such as Revolution) or even less frequently (such as Bravecto Plus). One product, Capstar, is short-acting, but very effective in quickly killing fleas (96% of adult fleas will be dead on a cat within two hours). It can be given every day for a short period to help you get a current infestation under control.[16]


(Be sure to purchase the right package: manufacturers offer different dosages depending upon your cat's weight.)


The three types of flea preventives 


Modern flea preventatives come in three styles and there are advantages and disadvantages to each: spot-on treatments, oral medications, and new-style collars.


Topical “spot-on” treatments. This medication is in a liquid form that is applied to the skin, usually at the base of the neck, in front of the shoulder blades. It’s absorbed through the skin, but fleas don’t have to bite your cat to die. Some spot-on treatments interrupt more than one stage in the flea lifecycle.
Spot-on products are very easy to apply, but since the medication is applied on the outside of the cat, children and other animals in the house could be exposed.
Many of these products are available without a prescription.
Oral medications. There are chewable tablets, such as Comfortis, as well as pill-style products, such as Capstar. These may be a good alternative to topical products, so long as you know how to give your cat a pill. (Here are some instructions, if you don't.) Some cats are less-cooperative than others, as you probably know.
Flea collars. These are not your Grandma’s flea collars. Today’s new-technology flea collars, such as Seresto, contain active ingredients that kill or repel fleas for months, by slowly releasing medication onto the skin over time. They’re thin, odorless, non-greasy, and water-resistant. They can be expensive upfront, but the overall monthly cost can be lower (or comparable) to other options.


With so many options on the market today, and new products being released all the time, it’s best to turn to your vet for a recommendation regarding the best product for your cat and your lifestyle.


I did everything right and I still have fleas!


cat scratching

Does it feel like you've done and tried everything you can to get rid of fleas but the fleas are still winning?


Remember, it can take many, many months to rid your pets, home, and yard of fleas. Fleas’ four-stage lifecycle can make it difficult to eradicate them; there are always fleas-to-be waiting in the wings, in their eggs or in their cocoons.


You must be persistent. Be sure that you are using new-technology, vet-recommended flea products on your pets, and be sure to NEVER MISS A DOSE. A single missed dose can mean starting from scratch with your flea eradication program.


It’s a lot of work to be continuously washing all that bedding, spraying, and vacuuming, but it must be done. If you let it slide for a few days, you’re letting all those fleas hatch and mate and make more fleas.


If you let your cats outside, understand that they may be hiding in flea-ridden places you have not necessarily treated, such as a shed, or under the car. They may also be going into other people’s houses and bringing their fleas home to you.


How do I know if my cat has fleas or ticks?



Not quite sure what’s infecting your cat? Fleas and ticks are actually quite easy to tell apart.


A tick has eight legs and moves very slowly, while fleas have six legs and scurry and jump. Ticks eventually attach themselves to your cat’s skin to continuously suck blood. The attached tick will feel like an unmoveable bump, especially as its body begins to swell from the blood it consumes.


Fleas move and hide so quickly that it can be hard to catch them “in the act.” Look for the other signs of a flea infection described above.


Aren’t there more “natural” ways to get rid of fleas?


Unfortunately, no. Fleas can become a dangerous and intractable problem that can easily get out of hand unless you use products that really work. In spite of what you may read on the Internet, the modern flea products that your veterinarian prescribes, are FDA approved to be cat safe. Check the label if you’re not sure. It should say, “Approved by FDA,” followed by a six-digit New Animal Drug Application (NADA, or ANADA) number.[17]


Conversely, so-called “natural” products can actually be quite dangerous – even lethal – for a cat. And they’re not likely to put a dent in your flea problem.


Read, “Are essential oils safe for cats?” to find out more.


But my cat is an indoor cat. She can’t have fleas, can she?


fleas on a person's leg

Unfortunately, the answer is yes, she can have fleas, even if she never steps foot outside.


Even if none of your pets go outdoors, “hitchhiker fleas” can hop onto you when you’re outside, or visiting a place with other animals. Fleas don’t live on humans (we’re not furry enough), but once indoors they’ll happily complete their lifecycle on your kitty.[18]


Your cat can get fleas at the veterinarian’s office, too (it’s a common reason other pet owners visit the vet!), and she can get fleas by merely sitting next to a screen door or window or on a porch.


Should I give my indoor-only cat flea preventative?


indoor cat has fleas

Yes, all cats, regardless of whether they live indoors or out, should be on flea and tick preventative all year round because they are still at risk of getting fleas.[19]


The health risk of a flea infection, for both humans and cats, and the expense and trouble involved in trying to eradicate fleas once they have made themselves at home in your house, make the investment in monthly flea preventative very worthwhile.


Do I need to give my cat flea medicine all year long?


Yes. Even though fleas need warmth to survive, they do have a special talent for finding it, even in the coldest winter months.


It’s a common misconception that you can stop giving flea prevention in winter. Fleas can survive outside in temperatures as low as 33 degrees for up to five days.[20] They can hide in warmish spots, like your garage or under the porch, until they can hitch a ride indoors and begin wrecking havoc.


I have a dog, too. Can I give my cat and dog the same flea preventative?


cat and dog

You cannot give a flea medication that is designed for a dog to a cat. Moreover, if you have both a dog and a cat in your household, you need to be very careful about the products you use on your dog.


Some flea products that are safe for dogs are extremely toxic to cats. A cat who is exposed to certain dog flea medications, just by living in the same household with a dog who has been treated with one of these products, can develop seizures, drooling, vomiting, and tremors, and can fall into a coma and die.


If you’ve treated your dog with one of these products, you should not allow your cat to have contact with him for at least 72 hours.[21] Even the tiniest dose can cause harm.


The most dangerous ingredients in some dog flea medications belong to a class of drugs called pyrethroids. Common pyrethroids include permethrin and cyphenothrin. A cat’s body doesn’t have the liver enzymes to metabolize these compounds.


Many flea preventatives for dogs contain more than one ingredient, so you’ll have to be a careful label reader, or ask your vet for advice. Here are some common dog flea/tick medications to avoid if you have cats:


  • K9 Advantix
  • Cerifect
  • Vectra 3D
  • Activyl Tick Plus
  • Bio Spot-On
  • Some Hartz products


This is NOT an exhaustive list, however, and new products are coming to market all the time. Check with your vet before choosing a dog flea preventative.


Did my cat get fleas from boarding while we were on vacation?


cat at kennel

Your cat didn’t have fleas – or so you thought – before you put her in boarding. But when you return from a long vacation, suddenly, there are fleas in your house.


While it’s possible he contracted fleas from the kennel or the pet-sitter’s home, it’s equally possible he didn’t.


Flea pupae can survive for up to a year, waiting patiently for just the right moment to emerge from their cocoons. They know if there are no cats in the house and thus no place to get a good meal.


But once you return from your trip, the waiting pupae will  burst open all at once and the newly-hatched fleas will jump on your cats, your dogs, and you, looking for a quick supper of blood.


How do the flea pupae know you’re home? They can feel the vibrations from you and your pets walking around the house and can sense the increased levels of carbon dioxide in the air from your breathing.[22]




Love Pinterest? Here's a Pinterest-friendly pin for your boards!

My cat has fleas - Pinterest-friendly pin




DAwn and Timmy
Dawn LaFontaine

Dawn LaFontaine is a lifelong animal lover who always seems to have a little pet hair in her keyboard. Her blog, Kitty Contemplations, helps cat guardians better understand and care for the special beings they share their lives and homes with. Her cat-products business, Cat in the Box, sells beautiful, well-made, and award-winning products that she designed to meet the biological needs of cats.




[1] “Flea.” Wikipedia, Wikimedia Foundation, 9 Nov. 2021,


[2] “How Far and High Can Fleas Jump?” FleaScience,


[3] “Flea Control in Cats.” Flea Control In Cats | VCA Animal Hospitals,


[4] Petco. “How to Get Rid of Fleas on Cats.” Petco, Petco, 1 Mar. 2022,


[5] “Fleas: A Source of Torment for Your Cat.” Cornell University College of Veterinary Medicine, 21 May 2018,


[6] “Flea Control in Cats.” Flea Control In Cats | VCA Animal Hospitals.


[7] Ward, Ernest. “Tapeworm Infection in Cats.” Tapeworm Infection In Cats | VCA Animal Hospitals,


[8] Tapeworms in Cats - Petlifesa.


[9] “4 Common Flea Diseases in Cats.” PetBasics,


[10] “Cat-Scratch Fever: Causes, Symptoms, Diagnosis, & Treatment.” WebMD, WebMD,


[11] Petco. “How to Get Rid of Fleas on Cats.”


[12] Tapeworms in Cats - Petlifesa.


[13] Victoria Nagy, et al. “Fleas Persist, but Reason Isn't Resistance.” Veterinary Practice News, 2 Mar. 2010,


[14] Flowers, Amy. “Protect Your Cat and Home from Fleas.” WebMD, WebMD, 26 Feb. 2021,


[15] “How to Treat Fleas in the Yard.” Scotts, Scotts 136 70, 9 Mar. 2022,


[16] “Picking a Flea & Tick Medication for Your Pet.” Dr. Justine Lee, 10 Mar. 2021,


[17] “How Can I Tell If a Flea and Tick Product Is Regulated by FDA or EPA?” U.S. Food and Drug Administration, FDA,


[18] “My Cat Doesn't Have Fleas - She Doesn't Go Outside!” Fairview Animal Hospital, 10 Sept. 2021,


[19] “5 Ways Indoor Cats Can Get Fleas or Ticks.” PetMD, PetMD, 22 Jan. 2021,


[20] “Why Should I Continue My Flea and Tick Prevention during Winter?” Ludwigs Corner Veterinary Hospital,


[21] Lee, Fiona. “Dangers of Using Canine Flea & Tick Medications on Cats.” Dangers Of Using Canine Flea & Tick Medications On Cats, 24 May 2021,


[22] “Flea Control in Cats.” Flea Control In Cats | VCA Animal Hospitals.


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