Revolution Plus for Cats: Overview, Dosage & Side Effects

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Revolution Plus for cats is a brand of topical, “spot-on” medication that prevents fleas, ticks, intestinal parasites, and heartworms. Revolution Plus contains the main ingredients selamectin and sarolaner. It is a newer incarnation of its older predecessor, Revolution for cats.

Revolution Plus for Cats Overview

Medication Type:
Avermectin topical antiparasiticide
Topical liquid solution
Prescription Required?:
FDA Approved?:
Life Stage:
Cat and kittens 8 weeks of age and older and weighing at least 2.8 pounds.
Brand Names:
Common Names:
Selamectin, sarolaner
Available Dosages:
Topical solution: up to 5 pounds (mauve packaging, 15 mg/tube), 5.1 to 15 pounds (blue packaging, 45 mg/tube), 15.1 22 pounds (taupe packaging, 60 mg/tube)
Expiration Range:
Products should be used before the expiration on the package. Packages should be stored below 86 degrees F (30 degrees C).

In this article, you’ll learn about Revolution Plus for cats, the ingredients it contains, the types of pests it targets and parasite protection it provides, possible side effects to consider, and some frequently asked questions.

For more information about the original Revolution product and more insight on how it compares to Revolution Plus, see Revolution for Cats.

About Revolution Plus for Cats

itchy cat

The main ingredient in Revolution products is selamectin. Selamectin is a topical avermectin antiparasiticide. Selamectin works by enhancing release of a neurotransmitter called GABA. In certain parasitic worms like roundworms and in arthropods like fleas, GABA inhibits nerve conduction. By enhancing GABA release, selamectin essentially causes paralysis and death of the parasites it targets.

Revolution Plus also includes sarolaner, which is an isoxazoline class acaricide/insecticide that inhibits GABA, leading to neuromuscular overstimulation and death of the parasites it targets. Sarolaner broadens Revolution Plus’ spectrum to include three types of ticks: the American dog tick, black-legged/deer tick, and the Gulf Coast tick.

Revolution Plus spot-on product is a monthly topical solution applied to a small target area or “spot” of the skin, usually in front of the shoulders at the back of the neck.

To get a lethal dose of selamectin or sarolaner, the parasites don’t have to bite a treated cat; simply coming in contact with the skin is enough. However, it’s important to note that Revolution products for cats do not provide true repellency that would prevent fleas or ticks from coming in contact with a pet.

What Does Revolution Plus Do for Cats?

Revolution Plus has action against many common parasites. Revolution Plus does the following:

  • Kills adult fleas
  • Prevents flea eggs from hatching
  • Treats and controls two intestinal parasites (roundworms and hookworms)
  • Treats and controls ear mite infestations
  • Prevents infection with mosquito-borne heartworms
  • Kills ticks

According to the manufacturer, when newly applied, Revolution Plus can start killing fleas within 12 hours, with a majority killed within 24 hours. When already applied prior to flea exposure, Revolution can start killing fleas within six hours, with a majority killed at 12 hours.

In a couple of studies, Revolution Plus was found to kill fleas before they could lay eggs, preventing further infestations from starting if the product is used consistently.

The manufacturer states that in lab studies, Revolution Plus started to kill the black-legged/deer tick within 24 hours with a little over 90% effectiveness for one month. It also demonstrated over 90% effectiveness against the Gulf Coast tick and the American dog tick.

As a heartworm preventative, Revolution Plus was found to be 100% effective in preventing the development of heartworms in cats when those cats were exposed to larvae about 30 days prior.

Revolution products can also help to control ear mites, which are pesky, itchy pests that occupy the ear canals, usually of young cats or kittens. Revolution Plus was over 99% effective at eliminating this parasite.

Lastly, Revolution plus was found to be nearly 100% effective against intestinal hookworms and roundworms in cats over a 60-day period of study.

Side Effects of Revolution Plus for Cats

Revolution Plus kills three common tick species (American dog tick, black-legged/deer tick, and Gulf Coast tick).

When used properly, side effects of Revolution products for cats are uncommon. Revolution Plus is labeled for cats 8 weeks and older. Revolution Plus is also restricted to cats weighing at least 2.8 pounds. Topical products like Revolution should never be ingested.

In clinical trials for Revolution Plus, a little less than 5% of cats showed signs of looking excessively tired, less than 4% showed signs of skin irritation, and about 3% showed signs of a decreased appetite. No hair loss was documented with Revolution Plus, which had previously been documented with regular Revolution.

At least some of the digestive upset and signs of excessive drooling that may be seen with use of topical products like Revolution Plus may have occurred secondary to cats licking the product off of themselves after application.

Products like Revolution Plus are very bitter tasting, so if a kitty were to lick a recently applied product off either themselves or a housemate, the bitter taste alone can lead to excessive drooling, agitation, and sometimes even vomiting.

According to DVM360, this effect is typically not a true toxicity, but a sometimes dramatic reaction to the bitter taste. Providing milk or liquid from a can of tuna can help resolve the signs in short order.

To avoid this from happening, it is important to apply any topical flea/tick product to the skin in front of the shoulder blades at the back of the neck, a location even the most flexible cat cannot reach to lick. In multiple cat households where lots of co-grooming occurs, separating housemate kitties for up to 24 hours after application to allow the product to fully dry may be advisable.

Although Revolution products for dogs and cats contain the same active ingredients, the manufacturer does not advise using a dog product on a cat, even if they are similar in weight. Sometimes, there are differences in the inactive ingredients between dog and cat products that would make them inappropriate to consider interchangeable.

Using Caution With Other Flea/Tick Products

While Revolution Plus for cats has been established as a safe product, the active ingredients may be found in other products in combination with other ingredients that are not safe for cats. This is especially the case with dog products like K9 Advtantix II, which contains permethrin, a substance that is extremely toxic to cats.

Fortunately, these products are now required to include a warning against use in cats. But just to be safe, when selecting a flea/tick product for your kitty, always make sure the product includes a picture of a cat and indicates the product is specifically for cats.

It is also always advisable if you have a pup and kitty who like to hang out together or groom each other to separate them for 24 hours after applying a topical product to your dog, especially if the product contains permethrin.

If you have any concerns for potential toxicity, even if you think your kitty might have just licked some Revolution Plus off her fur and is having a bitter taste reaction, it is always best to contact your veterinarian, the ASPCA Animal Poison Control Center (1-888-426-4435), or Pet Poison Helpline (1-855-764-7661) immediately for further advice.

And lastly, topical products like Revolution Plus have been known to cause skin and eye irritation in people. It is best to avoid contact with the solution during application and to wash your hands after.

Unlike regular Revolution, Revolution Plus contains the added ingredient sarolaner, which adds to its spectrum against ticks. Isoxazolines like sarolaner have been associated with adverse neurologic signs in some pets, including seizures and tremors. Use of Revolution Plus should be considered carefully in cats with any history of neurologic illness.

Revolution Plus for Cats Dosage

Before purchasing Revolution Plus, find out how much your cat weighs so you can buy the correct dosage.

Revolution Plus is typically applied every 30 days for the best protection. Revolution Plus is approved for use in cats and kittens 8 weeks of age and older.

Revolution Plus comes in three sizes as a topical solution for cats weighing 2.8 to 5.5 pounds, 5.5 to 11.1 pounds, and 11.1 to 22 pounds. For cats that exceed 22 pounds, the manufacturer recommends using a second dose in combination as appropriate (i.e., a cat weighing between 23 to 27 pounds would get one 11.1 to 22 pound dose combined with one 2.8 to 5.5 pound dose).

Safe use of Revolution Plus or any topical product for your kitty means always following all instructions on the packaging. Revolution Plus vials have a cap that first needs to be pushed down into the vial to puncture it.

The cap can then be removed, and the entire contents of the vial applied by parting the fur and applying to the skin along the back of the neck in front of the shoulders where a kitty cannot reach to lick it off of himself.

While Revolution Plus topical solution is considered to be waterproof within two hours of application, the manufacturer still recommends waiting 24 hours to bathe your kitty after application. Bathing shortly before application may also reduce its effectiveness.

If for some reason you are unsure if the product was administered correctly or whether all of it was applied, it is usually safest to not apply an additional dose.

If you have any questions about application or safety for Revolution Plus or any topical product, make sure to get in touch with your veterinarian.


Revolution Plus is the newest incarnation of Revolution, a product that has been used for cats for many years and is generally a safe and effective product when used properly. Because it is a heartworm preventative, you must obtain a prescription from your veterinarian before purchasing Revolution Plus.

Frequently Asked Questions

What does Revolution plus do for cats?

Revolution Plus has many actions against parasites in cats. It is effective at killing fleas and preventing further flea infestations, it kills and prevents three different kinds of ticks, prevents mosquito-borne heartworm disease, treats and controls the intestinal parasites hookworms and roundworms, and treats and controls ear mites. 

What is the difference between Revolution and Revolution Plus for cats?

The main difference is Revolution Plus contains the isoxazoline drug sarolaner in addtion to selamectin. Sarolaner allows for Revolution Plus to have a better spectrum of activity against ticks. 

While regular Revolution only provides some protection against the American dog tick and is not labeled for this in cats, Revolution Plus has labeled action against not just the American dog tick, but also the black-legged tick that carries Lyme disease, and the Gulf Coast tick. All three ticks are extremely common in the United States. 

Do you need a prescription for Revolution Plus for cats?

Yes. Because Revolution Plus is a heartworm preventative, it does require a prescription as all heartworm preventatives do. 

Even if ordered online, a prescription request will still need to be sent to your veterinarian for approval. The main reason for this is that some pets can be at a higher risk of a reaction for some products if the product is given or applied while the pet has an active heartworm infection. 

While cats are not as routinely tested for heartworm as dogs are, owing to the fact that only about 50% of cats truly infected with heartworm will show up positive for the disease on a test, it’s still important for a veterinarian to verify that a kitty is not showing signs of illness prior to starting.

How long does it take for Revolution Plus to work on cats?

According to the manufacturer, Revolution Plus starts working to kill fleas within 12 hours, with a majority killed within 24 hours. When already applied prior to flea exposure, Revolution can start killing fleas within six hours, with a majority killed at 12 hours.

Over 90% of the three ticks it targets were effectively killed on cats over a 60-day period of study, with the black-legged tick being killed within 24 hours. Ear mites, roundworms, and hookworms were all effectively killed by the product.

While Revolution has slower kill times for fleas and ticks compared to other topical products like Frontline Plus and Advantage II, the ingredients in Revolution Plus make it one of the best all-around products for cats, with the best broad spectrum of coverage targeting fleas, ticks, heartworm, and intestinal parasites.

If you feel you’re not seeing good efficacy from the product, especially when it comes to flea infestations, please consider the following.

The question of flea resistance to products like Revolution Plus and the idea that they don’t work comes up often. The 2017 article “Perception vs. Reality: Insecticide Resistance in Fleas” from DVM360 that refers to an article published in American Veterinarian that same year addresses this topic.

An entomology (“bug science”) professor from the University of California heavily investigated this question and concluded that while resistance has been seen to some flea treatment or prevention products, true chemical resistance in fleas with fipronil, imidacloprid, and some other newer products on the market has not yet been demonstrated.

In many cases, when a pup or kitty parent is still seeing live fleas on their pet after a product has been applied, this issue can most often be traced back to incorrect use or application of the product, as well as poor expectations.

Following are some common errors or misperceptions.

  • Incorrect application (i.e., applied to the fur not the skin, failing to apply the whole volume of product, failure to properly puncture or open a vial prior to application)
  • Failure to apply to all pets in the household. If one pet brings fleas indoors, they can jump onto all pets in the home. If all pets are not treated at the same time, flea infestations can persist.
  • Bathing. Baths are a common go-to, especially when live fleas are seen. However, while waterproof, Revolution products need 24 hours to spread throughout the oils on the skin. Bathing shortly before or after application removes oils from the skin as well as possibly the product itself.
  • Not treating long enough.  It can sometimes take as long as three months to clear out a flea infestation. So while most veterinarians advise year-round protection against fleas and ticks, a product like Revolution Plus should be used every month for at least three months during an active infestation. Flea eggs not cleared from the home environment are likely to continue hatching every couple of weeks, meaning a kitty that received only one monthly dose of Revolution Plus can get infested again a few weeks later if the dose is not repeated the next month.
  • Not treating year-round. Fleas have been known to over-winter indoors. Treating pets for only certain months of the year can leave open gaps in prevention for infestations to occur.
  • Failing to treat the environment. Because one flea can lay up to 50 eggs in just one day, the amount of eggs in a home environment with fleas can be staggering. If the environment is not treated effectively, continually hatching fleas may continue to be found on a treated pet.
  • Perceiving products as repellents. Always remember that most topical products like Revolution Plus do not have repellency action, meaning that fleas and ticks must come in contact with the skin to be killed. Heavily-infested outdoor areas as well as poorly-treated indoor infestations can be sources for large numbers of adult fleas to “suddenly” appear on a treated pet.

If you still feel there’s a true product IssueIf you feel you have applied a product properly and are addressing a flea infestation according to your vet’s instructions and still feel that a product is not working well, make sure to bring those concerns to your vet or contact the manufacturer of the product.

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About Dr. Chris Vanderhoof, DVM, MPH

Dr. Chris Vanderhoof is a 2013 graduate of the Virginia-Maryland College of Veterinary Medicine (VMCVM) at Virginia Tech, where he also earned a Masters in Public Health. He completed a rotating internship with Red Bank Veterinary Hospital in New Jersey and now works as a general practitioner in the Washington D.C. area. Dr. Vanderhoof is also a copywriter specializing in the animal health field and founder of Paramount Animal Health Writing Solutions, which can be found at Dr. Vanderhoof lives in the Northern Virginia area with his family, including 3 cats.

36 thoughts on “Revolution Plus for Cats: Overview, Dosage & Side Effects

    1. Avatar photoDr. Chris Vanderhoof, DVM, MPH Post author

      Hi Phylis, I’m sorry to hear you’re seeing these signs in your kitty. Skin irritation is uncommonly reported with Revolution Plus, though hair loss was not, at least not in clinical trials. If this was a recent application, it can help to use warm water and dish soap (like Dawn) to gently clean the area and remove any residue on the skin. Make sure to touch base with your veterinarian to see if any other recommendations might be made based on being more familiar with your cat’s health history. This would be worth reporting to Zoetis, the manufacturer, as perhaps incidents of hair loss have been reported and they could provide better information on any additional steps to take and what to expect. Needless to say, if your kitty had a bad skin reaction like this and is very sensitive to it, Revolution Plus is likely not an appropriate product to continue using for him.

  1. Jackie Ellis

    I have a 5 cat household. Their weight varies. I have one cat that weighs two pounds 13 pounds. Will the 5.6 lbs.- 11lbs. still work on this cat? I cannot buy single tubes for his weight. I am on a limited retirement budget. How to I fix this issue?

    1. Avatar photoDr. Chris Vanderhoof, DVM, MPH Post author

      Hi Jackie,
      Thanks for your question, but I unfortunately do not have a terrific answer for you. All flea/tick preventatives should be thought of as medication and their dosage ranges need to be followed closely. Using a range that exceeds a pet’s weight carries a greater risk of side effects. These products typically have a high safety margin, but the principle is still valid and they need to be used according to label. Using a dose range that is too low carries the risk of not being effective. If the remaining cats are in the proper range for what you have and have the product on, the risk of fleas would at least be lower if one kitty does not. You cannot split the vials or use a little less for a small cat or add a little more for a larger cat, as you then really have no idea what dose the cat is getting and these products were not meant to be used in that way, invalidating any guarantee the product has. I wish I could get you a better anwswer, but here’s really not much more you can do other than to have the correct dose ranges.

    1. Avatar photoDr. Chris Vanderhoof, DVM, MPH Post author

      Hi Cynthia,

      Consider holding off on another dose and first confirm what types of intestinal worms you’re seeing, as Revolution Plus can only kill certain ones, roundworms and hookworms. Of those two, only roundworms are visible, resembling long spaghetti-like strands.

      However, one of the most common types of worms we see in cats are tapeworms (which can be seen a couple weeks after an exposure to fleas), which resemble small rice-like segments. Revolution Plus cannot kill tapeworms. If you’re seeing worms resembling pieces of rice, using another dose of Revolution Plus will not help.

      It can help to send a photo of what you’re seeing to your vet to confirm worms are present and get a recommendation on the right type of dewormer. A product containing praziquantel is typically used for tapeworms.

      Other things to consider for persistent worms in the stool include sending a stool sample out through your vet.

      Hope that helps.

    1. Kristy

      Violet, I’m curious about your kitty. I realize it’s been a while since you posted, but this sounds exactly like what I’m going through. My cat has been the same way for 2 days, starting the morning after application. Limping, barely eating, and sleeping for two days straight. Did your cat recover? Do you remember how long it took?

    1. Avatar photoDr. Chris Vanderhoof, DVM, MPH Post author

      Hi Christine,

      Yes, if your cat is 10lb, you can use two of the 2.8-5.5 lb doses of Revolution Plus. The manufacturer does indicate that combination doses are acceptable. In terms of actual drug doses, each of the 2.8-5.5 lb doses is 15mg of selamectin and 2.5 mg sarolaner. The 5.6-11 lb dose contains 30 mg of selamectin and 5.0 mg of sarolaner. So in using two of the 2.8-5.5 lb doses, you are still giving the exact equivalent doses of the two drugs as you would be with a single dose of the 5.6-11 lb dose. Hope that helps.

      1. Anne Marie

        Thank you I was going to ask the same question my 8 pound 18 year old little girl had to go to sleep and I have two big boys 12 lbs and 17 lbs and about 9 tubes of 5 to 11 lbs left happy to hear I can use them on my big boys

  2. Teressa kooistra

    I took in a stray cat and have used revolution plus for the past four months. The last three week she has had two seizures
    Despite many tests and. Xrays my vet can find nothing wrong. Is it possible revolution plus could be the cause

    1. Avatar photoDr. Chris Vanderhoof, DVM, MPH Post author

      Hi Teressa,

      Thanks for sharing and I’m sorry to hear that you’re having these issues with your kitty.

      It is possible Revolution Plus could be related, but not certain. It contains two drugs. One is fluralaner, which is in the isoxazoline class, which provides most of the tick control. Isoxazolines have been associated with seizures in pets, though in my own experience, very uncommonly. Any product containing an isoxazoline carries this warning, but I don’t think it’s known how often this occurs.

      The second drug is selamectin, providing your flea and heartworm protection. Within the last year, researchers at WSU have identified that cats can have the MDR1 genetic mutation (which has been known about in dogs for about 20 years) that renders some cats sensitive to drugs including selamectin with seizures as a possible sign. However, this reportedly affects only 4% of cats, so is very rare.

      There can be many causes for seizures. In a stray cat, the risks can certainly be higher for infectious viral and parasitic causes, as well as previous trauma. I always worry about strays because we don’t know what they’ve had exposure to in their past life.

      If you’ve done general labwork and it looked normal, it does rule out several potential causes of seizures, but it’s not uncommon to see labwork look normal and be no closer to the underlying cause. An MRI can be an important part of working up a seizure disorder to look for structural abnormalities in the brain, but they tend to be expensive, so not often pursued.

      Whether the Revolution Plus is related or not, many vets will prudently advise to discontinue the product if a pet develops a seizure disorder, since the risk of a pet having seizures who is prone to them will be higher with an isoxazoline drug.

      If the Revolution Plus was related, you would expect the seizures to stop once the product is discontinued and out of a kitty’s system for 30 days. If the seizures persist long after Revolution Plus has been discontinued, then it certainly is more likely another cause is present. Best of luck.

    2. Jean Chapin

      Yes! See my comment below. I’ll never use it on my cats again. If it can kill just about any parasites on our cats for 3 months, what’s it doing to our cats?! I think I’ll stay with the tried and true.

  3. Jean Chapin

    I have 3 cats, all siblings, 2 had seizures 8 months ago, shortly after applying Revolution plus. After an extensive work up for each cat, and Mucho Dinero, my vet told me there was nothing wrong with my cats, and it was highly unlikely that the flea drops caused the seizures, and to keep an eye on them. I had the product in the house, but I chose not to use the revolution plus on my cats again because I suspected it caused the seizures. This week my vet told me it was safe and it was best to use the flea medicine because the fleas “are out there” this time of year. (My cats don’t have fleas btw). Against my better judgement I applied the Revolution + to all three cats, and today one of my cats had a seizure. Just putting it out there. Wish I would have listen to my instincts. Kitties are doing fine. They were not grand mal, but seemed focal. The cats were unable to focus, or walk for a few moments, then just sort of came out of it. And napped. If you see this type of activity in your cat after applying Revolution plus, I’d suggest not to use it. I am heartbroken that I put my cats through this.

    1. Avatar photoDr. Chris Vanderhoof, DVM, MPH Post author

      Hi Jean,

      I’m sorry to hear that your kitties had these events occur. Seizures are not a common side effect of Revolution Plus, but they have been reported in some field studies.

      We know that dogs with a mutation called the MDR1 mutation can have seizures and other neurologic effects from ivermectin, selamectin, and similar drugs in that class. Collies and collie-like herding breeds are often identified as carriers of this gene mutation.

      Research on this gene mutation in cats is much newer, but it is known that cats can also carry the MDR1 mutation. However, unlike in dogs where herding breeds like Collies are more predisposed, there is no specific association with any particular breeds in cats, making it almost impossible to predict what cats may carry it.

      In February of 2022, the same researchers at Washington State University who discovered the MDR1 gene mutation in dogs and developed the test to detect it, also released a test for cats. Here is a link for a press release article with more information (including a list of drugs these cats can be sensitive to) and a link to the WSU website for MDR1 testing.

      If your cats are genetically related and you’ve seen recurrent seizure events after using selamectin, having your cats tested for the MDR1 gene mutation would be a good consideration. There are some other drugs used in veterinary medicine that these cats cannot metabolize well. Knowing this ahead of time can help prevent future adverse effects.

  4. Jean Chapin

    Thanks, that’s really good information. Just curious, why my vet didn’t know about this. She seems up to date. I’ll share this with her. Also where does one get a list of those medicines that can cause adverse reactions in cats with MDR1 gene mutations?

  5. Avatar photoDr. Chris Vanderhoof, DVM, MPH Post author

    We’ve known about the MDR1 gene mutation in dogs for a long time and because it is classically associated with herding breeds, it’s been more straightforward for vets to discuss when we encounter those breeds. The MDR1 mutation in cats is very new. I’ve only become familiar with these findings within the last few months myself. Because there is no breed association in cats and according to WSU it only affect 4% of cats making it rare, it’s not a common discussion topic with cat owners. If you click on the press release article link, there is a list of medications pets carrying the mutation can be sensitive to. I can’t say of course that your cats have this gene mutation, but I would say with the circumstances you shared, it’s suspicious and worth testing them for it.

  6. Mary Ann Parker

    We have a 2yr old male (neutered) cat with Cerebellar Hyperplasia (sp?). The vet administered Revolution Plus for a bad ear mite infestation. Within a half hour he was having violent seizures, howling, hissing, and crying. The vet recommended he be put in a kennel cage until he recovered so he wouldn’t hurt himself. With his neurologic condition, he doesn’t walk very well, but now he couldn’t walk at all. He seemed to loose all control of his hind legs. He also lost control of his bladder. Even after the worst of the seizures stopped, after a few hours, he was very agitated. He was able to eat and drink as long as his bowls we very close to him. After four full days he has slowly regaining control of his hind legs, though still very unsteady. Be careful giving Revolution Plus to cats with known neurologic disorders.

    1. Avatar photoDr. Chris Vanderhoof, DVM, MPH Post author

      Hi Mary Ann, I’m sorry to hear this happened to your kitty. A cat having such a violent seizure response to the selamectin in Revolution is very rare. It’s hard to say if the cerebellar hypoplasia was directly related. There could also be a high suspicion for any cat having such a response to be a carrier of the MDR1 gene. I would feel that any cat having such a response should get tested for the MDR1 gene, since there are other medications these cats can be sensitive to as well. There is a link in this article explaining the MDR1 mutation in cats to Washington State University’s website where more info on the test is available.

      The Sarolaner in Revolution Plus is an isoxazoline, and this class of drugs has been associated with neurologic side effects like seizures, but more so in dogs. While reported in cats in some studies, it was not very commonly reported. I always suggest that isoxazolines be avoided in pets with actual seizure disorders but cats with cerebellar hypoplasia don’t typically have actual seizures, so it’s hard to say if there’s an actual connection there. Regardless of cause, having such a response should warrant avoiding not just Revolution Plus, but any medications in the same drug classes as selamectin and sarolaner.

  7. Mary Ann Parker

    Thank you for all your informaion. The cat is doing better, walking much better, tho still weak in his right hind leg. I am hoping that with more time he will regain his “normal” ability to get around.
    Mary Ann Parker

  8. Kayla

    Hello, I have two 3 and a half month old kittens. We just received Revolution Plus from the vet yesterday after their exams (they also both had the FVRCP shots, and an oral dose of deformed applied by the vet yesterday while at our 9am appointment), and I applied the medicine to them yesterday around 8pm. It is now 10am the next day, and they are itching and scratching like crazy, they are almost literally unable to stop, and not even able to sleep. Is this normal? I have never seen them scratch so much since I’ve had them. If this is normal, can you let me know why? Is it because it’s around the 12 hour mark, and the fleas are starting to bite them more because they are dying? Please let me know! Thank you so much!

    1. Avatar photoDr. Chris Vanderhoof, DVM, MPH Post author

      Hi Kayla,

      You didn’t mention that your kittens for sure had fleas prior to getting treated. But Revolution is a product that causes paralysis and death of the flea, not one that leads to overstimulation of the nervous system prior to death. So I wouldn’t expect to see a lot of irritation from flea excitement with use of Revolution Plus.

      With Revolution Plus, 2.5% of cats experienced itching according to the manufacturer label. It’s possible your kittens could be in this small percentage. I would not expect to see that type of behavior from the FVRCP vaccine or dewormer.

  9. Zane S

    We have 2 cats, a mother and her son, who we gave Revolution Plus to about a month ago. The kitten had already given himself hot spots from scratching flea bites before we gave him his first dose, but were told it was safe to still apply his dose. We applied it a bit lower than usual to avoid putting it on his hot spots, but within a few days, he had a bald spot on his back where he had scratched it open into another, larger hot spot. He had no other symptoms and was reacting perfectly fine besides scratching himself, and his mom reacted perfectly normal to hers as well. He is being treated and still healing up and getting better every day, but we aren’t sure if the medicine caused the bald spot or not, and he is due for his next dose very soon. We can’t afford to get another medicine and try it, so I wanted to ask if it would be safe to give him another dose of Rev Plus as originally planned?

    1. Avatar photoDr. Chris Vanderhoof, DVM, MPH Post author

      Hi Zane,

      This is unfortunately hard to answer. If the skin was already irritated so badly and the kitten was scratching some areas raw, the new area after applying the Revolution may have just been one more part of the bad dermatitis condition.

      Hair loss and skin irritation are two side effects seen with Revolution, but it’s hard to say if this would have happened without all of the other concerns with the skin.

      If Revolution is what you currently have and need to stick with, it may be worth trying another dose if the dermatitis is resolved. You’ll need to continue using some product for fleas for at least a couple more months to ensure the flea infestation is cleared.

      You may need to be prepared for the hair loss to occur again, in which case you’d know that Revolution isn’t a good choice for the kitten. But the hope is that the concurrent dermatitis issue was mostly to blame.

  10. Deb

    Does Revolution Plus cause nausea in cats. I’ve noticed Tommy usually has less of appetite after treatment for about 12-24 hrs. After last month’s treatment: his appetite was off for days. Even when giving different food; didnt want. Even treats ate just a bit. Gradually after 7+ days he wasn’t refusing to eat normal food & normal amount. Since it is fall; I’m tempted to not give treatment (New Hampshire)

    1. Avatar photoDr. Chris Vanderhoof, DVM, MPH Post author

      Hi Deb,

      Revolution can cause nausea in a small percentage of cats. This side effect is described as vomiting and anorexia in the clinical studies. For prevalence, in the large clinical study found in the medication insert, of just under 300 cats, 9 (3%) experienced anorexia/loss of appetite as you’re describing. In two other field studies mentioned, vomiting and decreased appetite were also seen.

      Do as you feel is best for your cat. However I would be remiss to not mention that you would be assuming some risk not using a product, especially if your cat goes outdoors. Even in the colder months in New Hampshire. I would be less concerned about mosquitos, but we can see fleas overwinter indoors, and ticks can overwinter under the snowpack.

      This video (from NH) went viral a couple years ago when a vet team removed a tick from a dog in January with heavy snow when the dog came in for porcupine-related injuries.

      It’s possible your cat may do better with another topical not absorbed systemically like Frontline or Bravecto.

      1. Deb

        Dr Vanderhoof, thank you for your information and advice. I will contact my vet on Monday to ask on Frontline or Bravecto. T.Y

  11. James uba

    I have 2 cats and I live in South Africa. I bought Revolution Plus from and it works well on one of my cats, but not as well on the other cat.

    Can you suggest why so?

    1. Avatar photoDr. Chris Vanderhoof, DVM, MPH Post author

      Hi James, you might need to be more specific for what you’re seeing that makes you feel it is less effective for your one cat and I may be able to answer your question better. But in general, Revolution products tend to work well as long as:
      1) the weight range is appropriate for the cat
      2) the dose is applied correctly
      3) the product is not expired (or some kind of immitation product)
      I mention the last one only because this issue has been reported when purchasing from second hand suppliers. You also need to have the right expectations. If one cat has an active infestation or if there is flea contamination in the home, it may take time to fully resolve an infestation.

  12. Donna

    I run a small cat rescue. Currently 20 cats but many more have come through. A few of them get sores on their foot pads that look like 2nd -3rd degree burns! It seem to correlate with the Revolution plus treatments. Is anyone else seeing this or is it all in my head?!

    1. Avatar photoDr. Chris Vanderhoof, DVM, MPH Post author

      Hi Donna,

      Most skin reactions from Revolution will occur at the application site. About 3-4% of cats have shown skin lesions not associated with the application site in field studies. They don’t indicate where those locations are, but they are probably very varied. Other cats have shown generalized signs of itching.

      I myself have not seen an association between Revolution and the types of lesions you describe. For that many cats within your rescue group to all have the same lesions would be unusual to be linked to Revolution. I think you would have to consider that something in the local environment is acting abrasive or caustic to their footpads.

  13. Donna

    Thank you for your prompt response! My vet believes this may be the culprit:
    Feline Plasma Cell Pododermatitis
    I appreciate your note, thank you!


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