Revolution For Cats: Dosage, Safety & Side Effects

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Revolution for cats is a brand of topical, “spot-on” flea, tick, intestinal parasite, and heartworm preventative containing the main ingredient selamectin. Currently, it is available as the two prescription products—Revolution for Cats and Revolution Plus for Cats.

Revolution For Cats Overview

Medication Type:
Avermectin topical antiparasiticide
Topical liquid solution
Prescription Required?:
FDA Approved?:
Life Stage:
Cats and kittens 8 weeks of age and older.
Brand Names:
Common Names:
Available Dosages:
Topical solution: up to 5lb (mauve packaging, 15mg/tube), 5.1-15lb (blue packaging, 45mg/tube), 15.1-22lb (taupe packaging, 60mg/tube)

Just want to learn about Revolution Plus? Click here to read our detailed guide.

In this article, you’ll learn about Revolution for cats, the ingredients both Revolution products contain, the types of pests they target, possible side effects to consider, and some frequently asked questions.

About Revolution For Cats

The main ingredient found 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 “spot-on” products are applied to the surface of a small target area or “spot” of the skin, usually in front of the shoulders at the back of the neck.

It is important to note that while these pesky pests are affected by Revolution by coming in contact with the skin and don’t have to actually bite a kitty to die, 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 Do For Cats?

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The original Revolution provides a spectrum of action against adult fleas and prevents flea eggs from hatching, targets the intestinal worms roundworms and hookworms, ear mites, and mosquito-borne heartworms. While selamectin has some action against the American dog tick, the original Revolution for cats is not indicated for treatment or prevention against ticks.

While not labeled for it, Revolution has also been successful in treating for the sarcoptic mange mite that causes scabies.

The newer Revolution Plus includes the addition of sarolaner, which is an isoxazoline class acaricide/insecticide that inhibits GABA, leading to neuromuscular overstimulation and death of the parasites it targets. The addition of sarolaner broadens Revolution Plus’ spectrum to include 3 ticks, the American dog tick, black-legged/deer tick, and the Gulf Coast tick.

According to the manufacturer, when newly applied, Revolution 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 6 hours with a majority killed at 12 hours.

The manufacturer states that in lab studies, Revolution Plus started to kill the black-legged/deer tick within 24 hours.

Side Effects Of Revolution For Cats

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

In clinical trials for Revolution, about 1% of cats were found to have a temporary hair loss at the application site, according to the manufacturer. Other signs seen in less than 0.5% of cats included digestive upset, poor appetite, drooling, an abnormally increased breathing rate, and muscle tremors.

In 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.

At least some of the digestive upset and signs of excessive drooling or salivation may have occurred secondary to kitties licking the product off of themselves after application. Products like Revolution 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’s article “Toxicology Brief: The 10 most common toxicoses in cats” this effect is typically not a true toxicity, but a sometimes dramatic reaction to the bitter taste. Providing milk or liquid from a 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.

And lastly, topical products like Revolution 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 hands after.

Using Caution With Other Flea/Tick Products

gray cat scratching itselft

In case you have a pup and kitty who like to hang out together or especially groom each other, the best practice is to separate them for 24 hours after applying a topical product to your dog.

While Revolution 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 Advantix II, which contains permethrin, which 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 off her fur and is having a bitter taste reaction, it is always best to contact your veterinarian, or the ASPCA Animal Poison Control Center for further advice.

And lastly, topical products like Revolution 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.

Revolution For Cats Dosage

Revolution products are typically applied for monthly dosing every 30 days for the best protection.

Always follow all instructions on the packaging for any topical product you use for your kitty. Revolution 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 products are considered to be waterproof within 2 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 products or any topical product, make sure to get in touch with your veterinarian.


Revolution 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, it is important to remember that both Revolution products require a prescription.

Frequently Asked Questions

What Does Revolution for Cats Treat?

The original Revolution for cats kills adult fleas and prevents flea eggs from hatching for one month, preventing and controlling flea infestations with continued use. It can also treat and control intestinal roundworm and hookworm infections, as well as ear mite infestations. It is labeled for prevention of mosquito-borne heartworm disease, but cannot be used to treat active heartworm disease.

Revolution Plus for cats has the same spectrum of coverage above, but the addition of sarolaner provides for the treatment and control of tick infestations caused by the black-legged/deer tick, Gulf Coast tick, and American dog tick. 

Do I Need a Prescription for Revolution for Cats?

Yes, indeed you do. All heartworm preventatives for pets require a prescription. 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 Effective is Revolution for Cats?

Revolution has slower kill times for fleas and ticks compared to other topical products like Frontline Plus and Advantage II. However, 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. 

The question of flea resistance to products like Revolution 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 3 months to clear out a flea infestation. So while most veterinarians advise year-round protection against fleas and ticks, a product like Revolution should be used every month for at least 3 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 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 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 Issue

If 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. 

Is Revolution the Best Flea Treatment for Cats?

When compared to Revolution, Advantage and Frontline products have faster kill times for fleas. Advantage II and Frontline GOLD also more effectively treat the entire flea life cycle including not just eggs but larvae as well. For getting rid of an active flea infestation in your home, Frontline Plus, Frontline GOLD, or Advantage II are probably better choices.

However, Revolution does have advantages to consider. When choosing a product, always make sure to think about all risks present to your kitty. With a spectrum that includes not just fleas but heartworms, ticks, sarcoptic mite mange, ear mites, and a couple intestinal parasites, it’s fairly unmatched in terms of having a pretty broad spectrum of coverage.

Most pets are at risk from all of these critters, but there can be regional variation. If you’re not sure what risks are more prevalent in your region, make sure to ask your veterinarian.

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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.

15 thoughts on “Revolution For Cats: Dosage, Safety & Side Effects

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

      Hi Julie, thanks for the question. If your kitty weighs up through 11.09 lb, the correct size would be the orange size. If your kitty weighs at least 11.1 lb, then the green size 11.1-22lb would be correct. This is especially the case if your cat has a history of a trending increase in weight or has fluctated over 11lb in weight before. If your cat has had a tendency to fluctuate under 11.1 lb, I would make sure to check with your vet and see what they think would be best. Essentially, if a kitty gets fleas, a tick borne disease, intestinal parasites, or heartworm disease while on Revolution Plus but the cat’s weight exceeds what the dosage range is that was applied, the company will not be obligated to assist with care or reimbursement. If your kitty generally tolerates Revolution Plus well, then even if he or she is at the low end of the dosage range, this is what you want to use.

  1. Kathy Norman

    I have a serious concern. This is the first time I have used revolution on my kitty. I got more on his fur then his skin. Should I be worried of making my little guy sick. That and I didn’t know it was raining when he went outside with his fresh dose on. Will he be alright?

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

      Hi Kathy,
      Thanks for your question. If the Revolution was applied more to the fur than on the skin, there is a good chance the medication may not be absorbed well, as it is absorbed through the skin, not the fur. As long as it was still applied in the correct location at the base of the head/neck and your kitty cannot lick it off, there is little risk of him getting sick from the medication. If he did go out in the rain within 24 hours of application though, there is a good chance much of the Revolution will be washed off, especially if most of it is in the fur. With both the application to the fur and the rain, and if you think it might have washed off, it’s likely okay to apply another dose. But if you are not comfortable with that, keep a close eye for fleas and ticks over the next month. I hope that’s helpful to you.

  2. Kathy

    Thank you Doc for your comforting advice it means alot to my little friend and myself. We are grateful for your time and compassion for our pet family members. God bless you.😇

  3. Kathy

    Hey Doc, Kathy here.Got a question for you. I am not sure if my kitty has parasites. He poops outside so it makes it difficult for a sample. He holds his tail away from his body and he generally looks like he doesn’t feel well. If he doesn’t have parasites will it hurt him if the vet gives a dewormer? And is there a triple wormer to address all in one pill?

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

      Hi Kathy,

      As far as intestinal parasites go, it is best for especially any outdoor kitty to be on a product regularly that can prevent them. Revolution Plus for example, helps to prevent roundworms and hookworms. If you have only just started a preventative medication for your kitty, it is best to give a dose of a broad spectrum dewormer, like fenbendazole.

      There is no dewormer that can cover everything, but fenbendazole covers the most and is very safe to use. An important one it does not cover is tapeworms, which cats can get from ingesting a flea or from hunting. Praziquantel is the most effective against tapeworms. Sometimes, tapeworm segments can be seen around a cat’s bottom, but if there is recent flea exposure within the last couple of weeks, it’s not wrong to treat for them too. Hope that helps.

  4. Linda

    Hi, I’ve been using Revolution Plus for years on both my cats and I’m normally very good about remembering to give them their monthly dose (those little calendar stickers included in the package are great!). I normally also check off on the calendar when I’ve given them their doses. So they were due for a dose last week, but I don’t have anything marked on the calendar, and I can’t remember whether I actually gave them their dose. I’m thinking I probably didn’t (I can remember thinking I needed to remember to do it, but I can’t remember actually doing it!) but I can’t be 100% sure. So I’m wondering, given that it’s March and we’re having weird weather ranging from the 20s all the way up to the 50s (Farenheit), whether it would be better to assume I didn’t dose them last week and give it to them now, or wait until next month. They are indoor-outdoor cats. Thanks!

    1. small mallory photoMallory Crusta

      I would err on the side of caution and wait until next month! If possible, you might want to keep them inside as much as you can until you’re ready to give the next dose.

  5. Chris Rahley

    My indoor kitty has allergies and my vet recommended Revolutions and I have used it in the past and kitty stops licking biting and scratching. Unfortunately, I can’t get my kitty to the vets as he freaks out and has to be sedated. I found some leftover Revolution in the box but it expired back in 2020. I figured it wouldn’t be full potency but would have something to help with his allergies. I gave him a dose but nothing happened and it’s been several days. Would it be ok to give him another dose to see if that helps or can you recommend another other the counter product to help him with his itching. He now has a hot spot on the side of his neck. I would prefer something like Revolutions that you just apply it to back of neck because he’s tough to actually rub a gel ointment or cream on his sore spot. Thank you for your help

  6. Chris Rahley

    Good morning. I have an indoor cat that is 10 years old and has seasonal allergies. The vet had recommended Revolution for the licking scratching and biting. Unfortunately, I have not been able to get my cat to the vets as he freaks out and has to be sedated. I left the windows open too long this year and he started scratching, biting and licking. I found some Revolution that had expired in 2020 and applied it to him last Saturday. Unfortunately it doesn’t appear to be working. Would it be ok to apply another dose as I would think there is still some potency left. If not can you recommend an over the counter medication like Revolution that is applied the same way to stop his scratching itching and biting. He has now developed a hot spot as well. Thank you

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

      Hi Chris,

      I can’t advise applying an expired product. If you feel Revolution has helped for this issue before, the product being expired could be why it’s not helping. If the product was applied properly, I would not suggest applying another dose so soon.

      If Revolution helps with skin itching, it’s usually addressing a flea allergy dermatitis, which can still occur in indoor only cats who are highly sensitive to a single flea bite. There are plenty of cases where an allergy flare up requires other medical approaches to address because the inflammation gets out of hand, or a hot spot gets infected, etc.

      You’re going to need at least an annual exam to have Revolution refilled for your cat, and if there’s a worsening hot spot etc, you’ll need an exam to decide what medical approach will be most effective to resolve it. I can sympathize with the challenges of your kitty needing sedation for a visit (I have patients that require this too). Sometimes an oral sedative can be sent home to make things a little easier, even just for a visual exam. I would still contact your vet to see what could be arranged.

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

      Hi Dave, it’s a good question, but to my knowledge there’s no indication that will happen. Selamectin only exists as a topical product currently and there are no oral forms. The closest you can probably get currently is combining Heartgard for cats with Credelio. Heartgard for cats contains ivermectin, which is a close relative of selamectin and has the same scope of prevention for heartworms and intestinal parasites. Credelio’s active ingredient is lotilaner, which is in the same drug class as sarolaner in Revolution Plus and has the same spectrum of action against fleas and ticks. Simparica Trio is a combination product that covers all these parasites in one chew for dogs, though it’s not approved for cats. Hopefully one day soon, something similar will be on the market for cats.


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