I hate fleas, and for good reason. Few creatures have had as much impact on world history — and have made cats more miserable — than the common flea. Let’s review the flea life cycle and some flea treatments for cats.
A flea’s life

Contrary to popular belief, fleas do not jump from cat to cat. Once a flea jumps on your cat, it makes itself at home there for its entire life. When a female flea lands on your cat, it immediately begins feeding on blood. Ingestion of blood is what allows the flea to become fertile and reproduce. Approximately 24 hours later, the flea starts laying eggs — about 50 per day. As the cat roams the house, he behaves like a living salt shaker, dropping flea eggs in the environment, mainly in areas where he sleeps and rests. About a week later, the flea eggs hatch, and little larvae emerge.
The larvae don’t like light, so they burrow into carpets, furniture and cracks in hardwood floors. Five to 12 days later, the larvae spin a cocoon in which they develop into pupae. One to three weeks later, little baby fleas emerge from the pupae. These baby fleas wait for your cat to wander by, then they hop on, and the life cycle starts all over again. Yes, it’s as creepy and gross as it sounds.
How to know if your cat has fleas
Diagnosing fleas is easy if live fleas are seen in the haircoat. Sometimes, fleas may not be seen, but “flea dirt” (a nicer term than flea poop, which is what it really is) is present. Flea dirt looks like pepper. Combing this dark material out of the haircoat onto a moistened paper towel will re-suspend the digested blood in the feces, leaving a red stain on the paper towel. This is a simple test, and it confirms the diagnosis.
At the very least, fleas will make your cat itchy and uncomfortable. But they can do more harm than that. Fleas can transmit conditions such as flea allergic dermatitis and tapeworms. They can also transmit Bartonella, the organism responsible for cat-scratch disease in humans. Heavily infested cats, especially kittens, can develop anemia due to blood loss from multiple flea bites.
Flea treatments for cats
Historically, the most effective approach to flea control was a three-step method: treatment of the yard, the house and the cat. The newer flea and tick control products, however, are so effective that treatment of the premises is rarely necessary, especially if the cat resides exclusively indoors. Cat parents now have a huge selection of flea control and flea treatment products at their disposal.
Topical flea treatments for cats
The most common flea control products contain either imidacloprid (Advantage), fipronil (Frontline), dinotefuran (Vectra), spinetoram (Cheristin) or selamectin (Revolution). These are applied to the skin on the back of the neck, where they sink in and spread throughout the layer of fat beneath the skin, killing any adult fleas present. They continue to kill fleas for at least 30 days. After 30 days, a new dose is applied.
Oral flea control products for cats
Oral flea control products are also available. Nitenpyram (Capstar) is good for heavy flea infestation. A single oral dose of nitenpyram will kill (within 30 minutes!) all of the adult fleas on a cat. It has no residual effect, however. Spinosad (Comfortis) is an oral formulation that kills 100 percent of adult fleas on a cat by 24 hours after administration. Spinosad has residual effect; it continues to kill adult fleas for 30 days before the next oral is required.
Lufenuron (Program) is an insect growth regulator. It works by interfering with the growth and development of fleas but has no effect on adult fleas. It is given orally once a month; however, an injectable form is available that is effective for six months. When a female flea ingests blood from a cat treated with lufenuron, the eggs she produces will be infertile.
Flea collars for cats
For cat owners who prefer flea collars, there is a collar (Seresto) that contains a sustained release formulation of the flea-killing compound imidacloprid, in combination with flumethrin, which kills ticks. It kills fleas and ticks for eight months. The collar also has a “break-away” mechanism, so if it gets caught on something, it will release, rather than cause injury to the cat.
Determining what’s safe when it comes to flea treatments for cats
In an effort to tap into the lucrative flea-control market, some manufacturers have produced over-the-counter flea control products that mimic the veterinary products in appearance. These are not safe for cats. They usually contain permethrin, an insecticide commonly found in low concentrations in some canine and feline flea sprays and shampoos. Cats can tolerate low concentrations of permethrin; however, these small single-dose tubes contain concentrated permethrin (45 percent to 65 percent). Concentrated permethrin spot-on products are labeled for use in dogs only and may cause severe and often fatal toxicosis if applied to cats.
Fleas have been a source of much misery for pet cats and dogs. Fortunately, modern flea control products are very effective. Different products offer different benefits, so consult your veterinarian to determine which product is best for you and your cat.
An aside on ticks and cats
Fortunately, ticks are less of a nuisance in cats, compared to dogs. Cats are meticulous groomers, and they usually remove most ticks from their coat before they attach. Those that do attach rarely cause problems because cats are much less susceptible to dangerous tick-borne diseases like Lyme disease, Ehrlichiosis and Rocky Mountain Spotted Fever. In my 29 years in practice, I’ve never seen a case in a cat.
Dr. Arnold Plotnick is the founder of Manhattan Cat Specialists, a feline-exclusive veterinary practice on Manhattan’s upper west side. He is also an author of The Original Cat Fancy Cat Bible. Dr. Plotnick is a frequent contributor to feline publications and websites, including his own blog, Cat Man Do. He lives in New York City with his cats, Mittens and Glitter.
Thumbnail: Photography ©GlobalP | Getty Images.
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37 thoughts on “A Vet Weighs In on Flea Treatments for Cats”
So… Absolutely nothing was mentioned about indoxacarb.
So far, all of the research I have done on it, indicates that it is largely safe for use on cats, and yet it never really gets mentioned by any vets. Years ago, I had tried everything listed in this post with no success. One dose of Activyl on my 12lb British Shorthair mix wiped them out in less than two days. It worked so scarily fast that I went and double-checked my prior research just for peace of mind.
Sorry Dr. , I respect your opinion about flea treatments on cats, but I have always had and used the philosophy and the belief that if their is a flea treatment that I can't pronounce because it is a manufactured chemical, then it probably is not good and possibly dangerous for my cat, and most of those chemicals you recommended are manufactured, I prefer natural essential oil treatments, as most of them are safe and harmless to cats but killers to fleas. Basically, if you can't pronounce it you don't want it.
Some essential oils are very toxic to cats, including clove and peppermint. Not everything "natural" is automatically safe. Please be careful and research even "natural" treatments.
You should probably stop consuming all of that Dihydrogen Monoxide then…
Did I miss page 2 where the vet “weighs in”?
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This was kind of useless. The Vet just outline the existing treatments. They didn’t really tell us what ones work best, if they have become resistant to fleas.
I agree!
I agree. I’ve searched for hours to find any discussion of what flea control method (in addition to vacuuming, etc.) is thought preferable for older or immunocompromised cats. My own vet doesn’t know. All the internet sites just outline what’s available. Surely there is an accumulated body of thought and experience on this topic – but WHERE?
I used 20 Mule Team Borax Laundry Detergent on my floors, carpets, etc. You “dust” lightly, leave for 24 hours and vacuum up. It kills literally every bug including fleas, in your house. It doesn’t hurt your animals and it kills the fleas. DO NOT wash your pets with this detergent. It is strictly for the floors, furniture, etc. Someone told me about this years ago after flea bombs, spraying, etc. just didn’t work…Good Luck (The detergent is in a box in your grocery store’s laundry detergent section.)
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I am sad to say that I am deeply offended that you have sworn on a website. The B word above.
It is the first time that I have seen such, not that that matters.
If you are talking about the word that starts with b u g? It is not a bad word here in the US. Most Americans don’t know the word has a different meaning in the U.K. In my life, if no offense was intended, I do not take offense. However their are exceptions. ????
not considered a curse word in the US. In the US it is used in the sense of “pain in the butt”.
I’m not offended in the least by the use of the word “buggers!”, because that’s exactly what fleas are. I’ve heard a lot worse and considering this is about getting rid of fleas, let’s just concentrate on the article for what it is. I live in the uk and don’t consider it offensive btw!
You are offended by the word “bugger” ?
You GOT TO BE JOKING RIGHT???? BUGGER” IS A HARD SUBSTANCE IN YUR NOSE..LMFAO????????
Hi, Carla. Actually, that’s a booger. Enjoy the rest of 2020 : )
I’ve never heard of a topical flea spray for spraying cats coats what was it called.
Are the products this vet is recommending otc or prescription only? Please differentiate.
Hi there,
Thanks for reaching out! Please contact your vet for specifics on these products or you can reach out to the author directly through this link: http://catexpert.blogspot.com/
I have used a flea & tick protector on my cat for 23 years now & he has not had a flea or tick since. It is a little tag that is non toxic & all natural. I get it from All Natural Pet company. It works with the energy of the cat. I don’t know how this works but it keeps the fleas & ticks off him.
Can you send me a link or the information? send it to angels-all (at) Comcast.net please?
can you give us the name of the company and the product?Thanks
Would love the name of this company
Have lived with cats for over 50 years and have never treated cats with anti-flea stuff of any kind. I have found it sufficient to treat their environment, especially their bedding and roosting areas. I use RAID with Precor, and 2 applications yearly are usually sufficient. And BTW, my cats are indoor cats, like all cats should be – but if your cat goes out, they will bring in fleas constantly.
for preventative purposes i’d say that either way works. personally, i prefer to treat the animal rather than the environment because then i feel confident they are protected no matter where they go (they are predominantly indoor as well but they might be out off the home for travel with me or trips to the vet.. and one of them really seems to like supervised time to hang out in the yard).
If i had 4+ cats, i think monthly prescription treatments for them would get too expensive to keep up with rather fast. in which case treating the environment would seem the only way to go.
when a flea problem does take hold (so not just routine prophylactic needs) I’ve found that you need to do both (environment and animal) to win.
Cats don’t have to go out to catch fleas. They can come in on your socks , pants, sweaters. All you have to do is walk past one stray or dog that has fleas and they hitch a ride back to your house. It will be a while before you notice it. My cats have never been outside one is allergic to fleas and will break out immediately with one bite and the other has thick hair and I can’t get them all off of her with frontline or any other high end brand of flea control. I can’t even see her skin when I part her coat she’s a British short hair.
I think many cats would disagree that they should be kept in doors. What’s wrong with an in-door/out-door cat?
Cats who go outside are consign danger. They are in danger of getting hit by a car; they can be injured or killed by a dog or other cats; they run the risk of ingesting something potentially toxic, like antifreeze; they are at the mercy of the elements…extremely hot and cold weather , etc, etc, etc. Indoor cats are safer and have much longer life spans than outdoor cats. People who argue that going outside is “their nature” make me sick.
A human that goes outside shares many of the same risks..
I agree!!! How do they know it’s their nature to go outside if they’ve never been outside?! An inside cat that’s never been outside doesn’t know the outside life!! An inside cat in an outside cat are two totally different in character in my own personal opinion. An indoor cat that goes outside is at risk because it doesn’t know how to defend itself against other cats or other animals but only knows love and warmth and heat and comfort and attention and an outdoor cat is raised and knows how to protect itself and is Street smarts so to speak. I completely agree with you and indoor cat belongs inside and does not know the outside life therefore it does not want to go outside and it’s nature!
But I do say if an indoor cat gets outside and has the instinct to run then it likes it outside better I guess but if it comes back inside it means it loves its home when its owners. Personal opinion and I never ever right Aramark or a comment but had you on this one this is actually the first one I’ve ever written!
I recsue cats from the streets it’s not pretty no cat or kitten should be outside I have 15 buried in my backyard from cars hitting them and 23 that are now mine that are safe and happy fixed and will live there live loved
If there a serious INFESTATION on the cat & house not even a professional EXTERMINATOR could take care of the problem in JUST ONE VISIT NO. VACUMING EVERYDAY & NIGHT WILL HELP. FLEA PRODUCTS TAKEN INTERANALLY CAN BECOME OR BE DAGEROUS AND EVEN FATAL YES THAT RIGHT DEATH! PLEASE DO YOUR RESEACH CARFULLY AFTER ALL ITS OUR RESPONSIBILITY TO EDUCATE OUESELVES. Dr FOSTERS AND SMITH .COM HAVE THE BEST FLEA DROPS IN THE MARKET IT WAS THE ONNY THING THAT WORKED FROM ALL THE ONES I TRIED FOR LESS THAN HALF PRICE OF FRONTLINE SAME INGREDIANTS EXCEPT THAT IT COMES STRIGHT FROM THEIR CATOLOG AND NOT FROM THE BLACK MARKET WHICK ARE BEING MADE TO LOOK LIKE THE REAL THING BUT THEY ARE NOT! BETTER PURCHASE RIGHT FROM THE SOURCE THAN EBAY OR AMAZON EVEN STORE COULD HAVE FAKE ONES WITHOUT REALIZING IT DEPENDING ON WHERE THEY GET THAY SUPPLIES. Remember to ALWAYS leave and have a bowl of fresh WATER for your Pets our beloved Fur babies.
You can’t write in all caps and expect to be taken seriously.. but i agree, it takes some persistence to knock out a significant flea problem. The one time i had a really bad outbreak was when i adopted my first cat and didn’t know any better.. the flea issue never crossed my mind at first.
I brought home a cat from the shelter with no flea control in place at all, then soon after took in a friendly stray who started showing up.. she brought in an army of fleas with her. I tired various basic otc products for a bit (carpet and bedding powders, shampoos, sprays etc) and each seemed to provide momentary relief, but the overall problem actually seemed to keep getting worse.
Finally i got serious.. the layout of my apartment was such that it was possible to isolate it into two sections with a closed hallway door. i got a bunch of foggers, sprayed the cats with a topical flea spray and got them collars. I put them in the ‘B’ side of the apt, plugged the gaps around the door with towels and fogged the ‘A’ side. when that settled down, i moved them and fogged the B side. then waited, to give time for remaning viable eggs to hatch and repeated (hopefully soon enough that new round of eggs haven’t been laid). After the second fogging cycle, i stopped seeing evidence of flea activity.. i did a third cycle just for good measure.
After that, i started getting prescription spot-on style flea meds from the vet to avoid that ever happening again.
For the record Ive used Nitenpyram and Lufenuron for years with no ill effects ever. Even when our 24 year old cat double dosed herself when I wasnt looking. I don’t trust over the counter flea drops. We used Frontline once and it killed our cat. Definitely get vet prescribed flea drops if you decide to go that route. So glad a vet weighed in on this.