The 8 Best Flea and Tick Treatments for Cats and Dogs in 2024

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Mel Plaut is a writer covering pets. They have tested hundreds of products for our best animal friends, including dog beds and pet fountains. Revolution Pets

The 8 Best Flea and Tick Treatments for Cats and Dogs in 2024 | Reviews by Wirecutter

After new research, we’ve updated several picks in this guide. Our first recommendations are Simparica Trio Chewable Tablets for dogs and Bravecto Plus Topical Solution for Cats.

Few things instill more terror in me than seeing a flea or tick setting up shop on my pet’s body (except, perhaps, finding them on my body). These bloodsucking parasites can spread diseases to people and pets alike, and a home infestation can be a nightmare to deal with. So even though flea and tick treatments add up to considerable expense and effort, they are necessary, and you must apply them for your pet’s entire life.

There’s nothing we can say to make this process cheaper or more fun, but we did enough research to help guide you. We looked at 20 treatments and picked eight—four for dogs, four for cats. A standard caution: Always consult your vet before giving any new medications to your pet.

This monthly, prescription-only chewable tablet for dogs treats and controls a wide spectrum of parasites, including fleas, hookworm, roundworm, and five kinds of ticks. It also helps prevent heartworm disease.

One chew lasts for 12 weeks, so you can administer it less frequently than any other oral treatment we recommend. But it doesn’t treat or prevent worm infections.

This collar offers eight-month protection, so it lasts much longer than a topical or an oral treatment. But it won’t protect against internal parasites, and some dogs may not like having an extra thing around their neck.

This monthly over-the-counter topical repels fleas, ticks, flies, and mosquitos, so they die without having to bite your dog. But it doesn’t protect dogs from internal parasites like heartworm.

This is a prescription topical solution for cats, offering a broad spectrum of coverage that lasts for two months. But it can’t be used on kittens who are younger than six months.

This monthly topical solution for cats offers similar coverage to Bravecto Plus. Yet this one also kills ear mites, and it can be given to kittens as young as eight weeks.

If your cat won’t sit still long enough for you to apply a greasy topical, or if you want to use something that will last for the longest time possible, this collar lasts up to eight months. But it doesn’t kill lice, mange, or worms.

This monthly topical is available over the counter, and it protects cats against fleas and a range of ticks. But it must be applied monthly, and it won’t fight against internal parasites, including heartworms.

Simparica Trio Chewable Tablets for Dogs offer the broadest protection for the lowest price we’ve found. It’s one of only a few products out there that use three targeted ingredients to kill fleas and five types of ticks, prevent heartworm, and treat hookworm and roundworm, giving your dog comprehensive protection in one monthly chewable tablet. This treatment can also effectively eliminate in-home flea infestations within four to eight weeks.

One chew lasts for 12 weeks, so you can administer it less frequently than any other oral treatment we recommend. But it doesn’t treat or prevent worm infections.

The Bravecto Chew for Dogs is the only oral treatment that can stand up to fleas and most ticks for up to 12 weeks (most others must be administered monthly). It can also eliminate a home flea infestation, but it doesn’t work against heartworm, hookworm, and roundworm, so you’ll need to pair it with a dedicated treatment for internal parasites.

The Seresto Flea and Tick Collar for Dogs both repels and kills fleas and ticks, so they don’t have to bite your pup in order to be neutralized—and this collar lasts for up to eight months. Although the Bravecto and Simparica Trio treatments provide a great baseline, when ticks are out in full force, these treatments might not completely block faster-moving tick-borne illnesses, like ehrlichiosis and Rocky Mountain spotted fever (Lyme moves much slower). This is the least expensive of our picks, and you can buy it without a prescription. But it doesn’t protect against worms, so you’ll need to combine it with a separate treatment.

This monthly over-the-counter topical repels fleas, ticks, flies, and mosquitos, so they die without having to bite your dog. But it doesn’t protect dogs from internal parasites like heartworm.

As with the Seresto collar, the K9 Advantix II Flea and Tick Spot Treatment for Dogs can be bought without a prescription. And it will help repel fleas and ticks, preventing them from biting your dog and potentially transmitting diseases. This topical treatment also fends off mosquitoes and biting flies. However, since it doesn’t penetrate beneath the surface of a dog’s skin and coat, you’ll still need to combine it with a treatment for internal parasites.

This is a prescription topical solution for cats, offering a broad spectrum of coverage that lasts for two months. But it can’t be used on kittens who are younger than six months.

Bravecto Plus Topical Solution for Cats gets absorbed through a cat’s skin into the bloodstream, so it can tackle both external and internal parasites, and it lasts twice as long as most other treatments. It handily kills fleas, ticks, roundworms, and hookworms, and it prevents heartworm infection for two months, mercifully reducing how often you’ll need to give it to your cat. It can also help get rid of flea infestations in the home.

This monthly topical solution for cats offers similar coverage to Bravecto Plus. Yet this one also kills ear mites, and it can be given to kittens as young as eight weeks.

In addition to fleas and internal parasites, Revolution Plus Topical Solution for Cats takes on four ticks, including the lone star tick and the Gulf Coast tick, which Bravecto Plus doesn’t cover. It can also help get rid of indoor flea infestations, and it’s the only one of our picks that’s explicitly labeled to kill ear mites. But it must be applied monthly, twice as often as Bravecto Plus.

If your cat will agree to wear it, the Seresto Flea and Tick Collar for Cats can repel and kill fleas and ticks for up to eight months. The repellent action means that these pests will die without having to feed on your cat’s blood and potentially transmitting disease. But, as is true of our other budget pick, this collar’s ingredients stay only on the surface of your cat’s skin and hair, so it won’t protect from heartworm, hookworm, and roundworm. Since heartworm is incurable in cats, you’ll still need to be vigilant with a separate treatment to prevent it.

Frontline Plus Flea and Tick Spot Treatment for Cats kills adult fleas and disrupts the flea life cycle, preventing their eggs and larvae from developing correctly. As an over-the-counter monthly medication, Frontline Plus stays on the surface of your cat’s skin and fur, and it’s less expensive than our prescription-only picks, which enter your animal’s bloodstream. So it doesn’t prevent heartworm or treat intestinal parasites, like hookworm and roundworm.

For the most recent update to this guide, we squinted at the tiny type of more than two-dozen product inserts and prescriber information sheets for a swath of flea and tick treatments. We compared their active ingredients, efficacy, proven timing, and potential side effects. We also interviewed several experts, including an entomologist, a clinical and shelter veterinarian at Cornell University, and a veterinary parasitologist who teaches at Oklahoma State University, located in what’s commonly called the “tick belt.” I also spoke with a veterinary parasitologist from a pharmaceutical company that makes several flea and tick treatments.

We checked in with a spokesperson for the Food and Drug Administration (FDA) and consulted the Environmental Protection Agency’s (EPA) online resources. We read nearly a dozen scientific studies, and we scoured tick-prevalence maps published by the Centers for Disease Control and Prevention (CDC). We learned about flea and tick life cycles, as well as the broad range of illnesses they can spread to pets and people. We also consulted the Companion Animal Parasite Council’s website, which has in-depth information about pets and the parasites that love to feed on them.

For an earlier version of this guide, Kaitlyn Wells spoke with Jennifer Gervais, formerly a pesticide specialist at the National Pesticide Information Center, and Ken Labbe, a spokesperson for the U.S. Environmental Protection Agency. She also consulted with Dr. Douglas Kratt, president of the American Veterinary Medical Association at the time of the interview; Dr. Tierra Price, an emergency veterinarian and founder of the BlackDVM Network; and Dr. Jennifer Welser, chief medical officer at Mars Veterinary Health. And she discussed product safety with Dr. Tina Wismer, senior director of the ASPCA Animal Poison Control Center.

Personally, I’ve had the unpleasant experience of finding fleas and ticks on my pets and in my home. Over the course of two decades, I perfected the jiu jitsu required to keep my cats still as I fumbled with a tube of topical parasiticide. And each month, when I am refreshing my dog’s meds, I trick him into eating his “special” treats.

If you’re not careful, fleas and ticks can hitch a ride on your pet and camp out in your home—or, worse, on your body. Your pet can also pick up heartworm from mosquitoes, as well as other intestinal parasites, like hookworm and roundworm (PDF), from contact with even small traces of animal poop.

And while your pets can get terribly sick from hosting these parasites, you and your human family members may also be exposed to an alarming variety of illnesses. The best way to avoid this nasty ordeal is by consistently giving your dogs and cats an effective anti-parasite treatment—and to keep up with it year-round.

“To think of them as a seasonal concern is likely setting yourself or your pets up for exposure,” said Aly Cohen, a veterinarian at Cornell University’s Riney Canine Health Center and a clinical instructor at Maddie’s Shelter Medicine Program. Ticks can emerge when temperatures hit 40 degrees Fahrenheit and above, but they’ve been seen in even colder temps, especially when there hasn’t been a prolonged freeze.

Fleas can also come out in the winter. “You’ll get these freak conditions where you get to a period where it’s relatively warm for three, four weeks, and the humidity is up. And it’s ideal for a flea outbreak,” said Michael Rust, an entomologist and distinguished professor at UC Riverside.

Susan Little, a veterinarian and parasitologist at Oklahoma State University, agrees. “The key thing with parasite control is it’s got to be there all the time. It’s got to be constantly on board. Because you don’t know when the parasites will be introduced, when the pets will encounter them. And so you can’t let your guard down,” she told us. (Little has also consulted for several pharmaceutical companies that make flea and tick treatments, including Merck, Elanco, Zoetis, and Boehringer Ingelheim.)

But no treatment is foolproof, especially if you’re in a high-tick-burden area. “No matter what you use, there’s a chance for breakthrough,” said Cohen. So you shouldn’t neglect routine tick checks, no matter what treatment you’re using.

“We have a half-dozen important tick species and probably 80 tick species all over the US,” Little said, so some tailoring might be necessary. The CDC publishes maps online, so you can see where specific ticks are prevalent. Your state may also publish a list of ticks to watch out for.

Before you give anything to your pet, talk to your vet. They can help you choose the right product for your animal’s age, weight, and medical history. They should also know what treatments work best in your region.

We considered 20 treatments and picked eight—four for dogs, four for cats. We evaluated each one based on the following criteria:

Cats are more prone to reject (or throw up) a pill or treat, so we mostly favored liquid topicals for them. Dogs are usually less discriminating and might inhale a flavored oral treatment before they realize it’s medicine, so our dog picks are mostly chewables. Both species might tolerate a flea/tick collar; this is a convenient method of treatment, and it lasts much longer than orals or topicals (but flea/tick collars don’t treat internal parasites).

Sprays are not convenient for regular use, and they leave a lot of room for error, so we dismissed them. And we don’t recommend any of the alternative treatments out there: Ultrasonic devices haven’t been proved effective, and though some essential oils might kill or repel fleas, they can also be toxic to some pets. Also, because they don’t break the flea life cycle, their effects don’t last long, Rust said.

Unfortunately, “there’s not one product to rule them all,” Little told us. But we looked for treatments that had the broadest coverage or that could be safely combined with another treatment to get the most protection.

We compared the drugs that have been on the market since the 1990s to a newer class of drugs called isoxazolines, in use since 2014. Isoxazolines are long-lasting and can tackle a variety of ticks. “We’ve seen expansion of tick populations, increased numbers of ticks where they’ve long been present, and so higher risk of tick infestation than ever before. So I don’t consider flea control enough for any pet. It has to be flea and tick control,” Little said. Isoxazolines have also been shown to be effective against ear mites, and they can even beat back a home flea infestation within four to eight weeks (a severe infestation could take longer).

We favored combination products that can also tackle internal parasites like heartworm, hookworm, and roundworm, to help limit the number of treatments you need to administer. But some of the flea/tick-only products might be a better fit for some pets, so we included those as well. Just be sure to ask your vet about combining these with a dedicated treatment for internal parasites.

All in all, there are a lot of parasites to protect against. We made a visual guide comparing our picks for dogs and cats on breadth of coverage.

“Puppies and kittens can be little flea factories,” Little told us. “You want to make sure that the home doesn’t become infested, because then you have a bigger problem,” she added. We looked for products that were labeled for use as early as possible in a dog or cat’s life.

The best treatment is the one you actually give to your pet. But we get it: Life can get busy, and things fall through the cracks, so we favored medications that protect your pet for at least a month, if not longer. But no matter the frequency of a treatment, you should set a repeating calendar event to remind you when a treatment is due.

These medications aren’t cheap, and you’ll have to keep buying them for your pet’s entire life. But they might ultimately save you money in the end by keeping your pet out of the vet’s office. We compared what each product would cost over the course of a year, and we favored those that packed in the most protection for the price. Many of them are prescription-only. For people without access to a vet, we sought over-the-counter medications that were widely available at a minimal price with few compromises. For each pick, we list an approximate cost per year as of 2024.

Simparica Trio Chewable Tablets for Dogs is a monthly chewable treatment that offers the broadest protection for the lowest price. It kills fleas and ticks, prevents heartworm, and treats hookworm and roundworm, all with one liver-flavored nugget. It can be used in puppies eight weeks and older who weigh at least 2.8 pounds.

Simparica Trio is one of the few products we’ve found that uses three active ingredients to tackle a wide spectrum of parasites. (The only other treatment we’ve seen with similarly broad coverage for dogs is Nexgard Plus, which is more expensive and covers one fewer tick.)

The first of these ingredients is an isoxazoline compound called sarolaner (all isoxazolines end in “laner”). It kills any fleas and ticks that are camping out on your pet. And it can also help get home flea infestations under control within four to eight weeks, if all of your pets are treated regularly, according to Chris Adolph, a veterinary parasitologist on staff at Zoetis, the company that makes Simparica Trio.

The second and third ingredients are moxidectin, which protects against heartworm, and pyrantel, “which extends the spectrum to include adult and immature stages of two species of hookworms, two species of roundworms,” Adolph said.

Simparica Trio kills five types of ticks, including the Gulf Coast tick. Concern over this tick is growing, as it expands its geography up the East Coast and into the Midwest, according to the Companion Animal Parasite Council (video).

But Simparica Trio is not currently labeled for the Asian longhorned tick, so if this tick is a concern for you, our also-great pick might be a better choice.

You can usually get a good value per dose in the six-count packaging, although buying it this way can be a significant cost all at once. Check the color-colored ovals on the front of the box to make sure you’re buying for the appropriate weight range, which spans six groups of dogs, from 2.8 up to 132 pounds. You can give these tablets to even bigger dogs, too, but as with most of these treatments, you’ll have to calculate the correct number to give them. You can give this tablet with or without food, and it comes in an individually wrapped blister pack.

Price per year: about $340 to $395 (depending on dosage)

One chew lasts for 12 weeks, so you can administer it less frequently than any other oral treatment we recommend. But it doesn’t treat or prevent worm infections.

The Bravecto Chew for Dogs is the only flea and tick treatment we’ve seen that kills fleas and some ticks for up to 12 weeks, so administration is infrequent and convenient. Bravecto is also our only pick that kills the Asian longhorned tick.

Bravecto’s active ingredient is fluralaner, an isoxazoline, so it can help with home flea infestations. But it doesn’t contain any drugs to prevent heartworm or treat hookworm and roundworm; you’ll need to buy another product that handles these internal parasites.

Of the five ticks Bravecto attacks, only four of them are controlled for the full 12 weeks. If you’re in an area with a large population of the lone star tick (PDF), you should give your dog Bravecto every eight weeks instead, as indicated on the product label. This provides full coverage without any danger to your pup from either the medication or the ticks, and you still have to apply it only half as often as most of our other picks. It also comes in a topical, if your dog has special dietary requirements or doesn’t like chews.

Like Simparica Trio tablets, the Bravecto Chew is available in multiple dosages, for dogs ranging in weight from 4.4 to 123 pounds (there’s a color scheme associated with each weight range on the front of the box). According to the insert, dogs who weigh over 123 pounds “should be administered the appropriate combination of chews.” Bravecto should be given with food, and the tablet comes in a sealed blister pack.

Price per year: about $315 to $335 (for 12-week administration, depending on dosage)

The Seresto Flea and Tick Collar for Dogs kills and also repels fleas and ticks, so they don’t need to feed on an animal’s blood in order to ingest the treatment. This means you likely won’t find as many dying or dead ticks attached to your pooch as you would with oral treatments and with topicals that enter the bloodstream.

Some tick-borne infections, like ehrlichiosis and Rocky Mountain spotted fever, can be transmitted within a few hours after a tick has attached (with Lyme, however, it takes between more than 24 hours for a tick to transmit). And while isoxazolines can reduce the transmission of these faster-moving illnesses, they may not block them 100% of the time. Susan Little told us that many veterinarians recommend using an isoxazoline “as a baseline,” and then adding a repellent collar to keep pests at bay if you go to a tick-heavy area or if it’s the height of tick season.

The Seresto collar works for up to eight months, the longest of any of our picks. But since it addresses only external parasites, you’ll still need to use a separate product to protect against heartworm, hookworm, and roundworm. And in recent years, there have been some safety issues concerning the collar’s release mechanism.

The collar is available in two sizes, one for small dogs who weigh up to 18 pounds and one for “large dogs” who weigh over 18 pounds. It comes in a protective bag inside a round canister. The collar is coiled and connected to itself with plastic pieces; you need to remove these before putting the collar on your pooch (otherwise your dog may get scratched).

This monthly over-the-counter topical repels fleas, ticks, flies, and mosquitos, so they die without having to bite your dog. But it doesn’t protect dogs from internal parasites like heartworm.

Like the Seresto collar, K9 Advantix II Flea and Tick Spot Treatment for Dogs is a relatively inexpensive monthly topical treatment that, unlike the chewables, can be bought over the counter. It kills and also repels fleas, ticks, and lice. Like the Seresto collar, it helps stop ticks from attaching to your dog.

Advantix II also kills and repels annoying biting flies and mosquitos that can carry heartworm disease and West Nile virus. But while it helps keep disease-spreading mosquitoes from biting your dog, it stays on the surface of the skin and hair coat. It doesn’t enter a dog’s bloodstream, as Bravecto and Simparica Trio do, so it won’t prevent heartworm, nor will it treat intestinal parasites like hookworm and roundworm. Therefore, you’ll still need a separate medication for those.

Advantix II contains imidacloprid (which has been used to control fleas since the mid-1990s) and permethrin (which is also often used in human insect repellents). But permethrin is toxic to cats in high concentrations, so this product should be kept far away from your feline friends.

If you have both dogs and cats in the home, you can still use Advantix II, but the label instructs you to keep treated dogs separated from your cats for 24 hours after applying it. (If a cat ingests Advantix II, contact your vet right away.)

The label also warns that Advantix II is “extremely toxic to aquatic organisms,” and it suggests using caution when throwing away the packaging, making sure not to add the product to water.

Advantix II comes in a tube with a seal that you break with the cap. It’s available in four dosages; the smallest one is indicated for dogs who weigh between 4 and 10 pounds, and the largest one is for dogs who weigh over 55 pounds.

This is a prescription topical solution for cats, offering a broad spectrum of coverage that lasts for two months. But it can’t be used on kittens who are younger than six months.

The beauty of Bravecto Plus Topical Solution for Cats is that you only have to put it on your cat every other month. If your cat is anything like mine used to be, they’ll disappear into the deepest recesses under the bed the moment they hear you open the tube. Bravecto Plus minimizes the unpleasantness to six times a year, instead of the usual 12. It’s a topical liquid, but, unlike our budget picks, Bravecto is absorbed into a cat’s bloodstream, so it works systemically.

Bravecto Plus contains fluralaner, an isoxazoline compound, which kills fleas and ticks, and it beats back most indoor flea infestations within a few months. Unlike basic Bravecto, a former pick that is applied every 12 weeks, the Plus formula also contains moxidectin, which protects cats from heartworm and treats roundworm and hookworm infections. (Revolution Plus, our runner-up pick, also protects cats from these parasitic worms.)

There’s no cure for heartworm disease in cats, notes the American Heartworm Society, so you need to protect your cat from getting it in the first place. Although the bimonthly treatment schedule is convenient, you can’t use Bravecto Plus in kittens who are younger than six months old.

Bravecto Plus comes in a tube, with a cap you must twist once around to break the seal (the cap stays on). The company suggests wearing gloves during application. It comes in three dosages, for weights ranging from 2.6 to 27.5 pounds. For cats who are heavier than that, Bravecto Plus includes a chart to help you figure out the right number of tubes to give.

This monthly topical solution for cats offers similar coverage to Bravecto Plus. Yet this one also kills ear mites, and it can be given to kittens as young as eight weeks.

Revolution Plus Topical Solution for Cats is a monthly topical with similar coverage to Bravecto Plus, handily killing fleas, ticks, hookworm, and roundworm, and preventing heartworm. It contains an isoxazoline compound called sarolaner, so it can also help with home flea infestations. This treatment works systemically, and it costs nearly the same as our top pick when treatment is calculated over the course of a year. But Revolution Plus must be applied every month, twice as frequently as the Bravecto Plus treatment.

Revolution Plus takes on four tick species, including the lone star and Gulf Coast ticks, which Bravecto Plus doesn’t cover. But it doesn’t kill the Asian longhorned tick, so if this tick is common in your area, Bravecto Plus might be a better choice.

While isoxazoline compounds have been shown to kill ear mites, Revolution Plus is the only one of our picks that is explicitly labeled for this use. It combines sarolaner, the same isoxazoline that’s in Simparica Trio, with selamectin, which tackles ear mites and internal parasites. So if ear mites are a particular problem for your cat, this product should help.

Like Bravecto Plus, Revolution Plus is available in three dosages, for weights ranging from 2.8 to 22 pounds, with color-coded boxes and tube caps for each one. To break the seal on the tube, you press the color-coded cap until it clicks, and then you remove it before applying it to the back of your cat’s neck (video).

Price per year: about $255 to $300 (depending on dosage)

If your cat goes weapons hot when you try to apply topical medications, you both might find a collar to be less stressful. Like the dog version, the Seresto Flea and Tick Collar for Cats kills and also repels fleas and ticks for eight months, far longer than the one- or two-month coverage of our other picks. This means that fleas and ticks don’t have to make a meal of your cat’s blood in order for the poison to work.

The Seresto collar is less expensive than our other picks, and it can be used on kittens who are at least 10 weeks old. However, it doesn’t protect against or treat parasitic worms (as our Bravecto Plus pick does), so you’ll still need to give your cat a separate treatment for those.

Some cats may experience side effects of redness or inflammation near the collar. If this sounds like your pet, try an oral or topical treatment instead. And some cats might not appreciate having the extra bulk of a collar around their neck. There have also been some safety concerns in recent years over the collar’s quick-release mechanism. The EPA reviewed these and has required the manufacturer to address them.

The collar comes in a round canister and sealed inside a protective bag. To use the collar, you need to uncoil it, and then discard all of the plastic bits that were holding it together, so they don’t scratch your cat. Make sure you can fit two fingers between your cat’s neck and the collar.

One of the ingredients in Frontline Plus Flea and Tick Spot Treatment for Cats (an insecticide called fipronil) has been killing fleas since the 1990s. It changed the paradigm of how flea control was approached, according to entomologist Michael Rust, making it easier to eliminate home flea infestations and ending the need for outdoor sprays and indoor bug bombs.

Frontline Plus combines fipronil with methoprene, an insect growth regulator that increases the original product’s efficacy by disrupting the flea life cycle, according to Rust. Since it’s an over-the-counter monthly medication, it’s cheaper than our prescription picks from Bravecto and Revolution.

In addition to fleas, it kills four types of ticks and chewing lice, and it can be used on kittens as young as eight weeks. There are also a few cheaper, generic versions available that have the same ingredients.

But Frontline Plus doesn't tackle or prevent internal parasites like heartworm, and some studies have shown that isoxazoline compounds are more effective against fleas and ticks over time. Still, this is one of the cheapest good options available. If you don’t have access to a vet, it’s better than leaving your cat untreated.

The liquid comes in a plastic tube, which you need to cut out of a blister pack. Once you’ve done that, it’s easy to snap the top of the tube open. Unlike our other topical treatment picks for cats, Frontline Plus is only available in one dosage, for cats weighing over 1.5 pounds.

Prescription products that are ingested orally or are absorbed through the skin and enter an animal’s bloodstream are regulated by the FDA; over-the-counter treatments that stay on the surface of the skin and hair coat fall under the EPA’s jurisdiction. For both types, the box and/or product insert should include a registration or application number, usually in tiny type.

The FDA and EPA ensure that these products are safe and effective, but the experts we spoke with pointed out that most still have some risks, from skin irritation to seizures. If your pet has a minor reaction to a flea and tick product, such as application-site discomfort, don’t freak out. “I do see topical site reactions, and it’s not common, but some animals just have more sensitive skin than others,” said Tierra Price, an emergency veterinarian and the founder of the BlackDVM Network.

Still, anecdotes about potential reactions can leave some pet owners on guard—especially when those reactions make headlines. The FDA has issued a fact sheet warning about adverse effects associated with products containing isoxazolines. “If you have a dog with epilepsy or any kind of history of neurologic concerns, then that’s not the right product to use,” said veterinary parasitologist Susan Little.

Seresto, our flea-and-tick collar pick, has been linked to some pet injuries and deaths, leading the EPA to conduct a review of the product. But the rate of adverse events associated with the collar was 0.116%, or 1 in every 1,000 collars sold in the US, according to the American Veterinary Medical Association.

Some dog breeds, like collies, can have a genetic mutation that makes them sensitive to the active ingredient used in many heartworm preventatives. In high doses, these drugs can be dangerous, but any of the prescription heartworm preventatives you can get from a vet are safe, and they have all been approved by the FDA.

“It’s when some owners will go to the feed store and buy a cattle product and give it to their dog, and the dose is way too high. That’s when you can get the adverse event,” Little said. The stuff they sell for cows and horses is not meant for your pooch, so don’t DIY your pup’s parasite control.

Always make sure you’re using species-specific products. What we use for our own bodies might be harmful to our pets. Permethrin, for example, is usually safe for humans and dogs, but it’s toxic to cats and should never be used on them.

Lastly, be sure to avoid counterfeit products by getting them straight from your vet or from a reputable online retailer that can guarantee the product’s authenticity.

If you have any issues with flea and tick products, you should always report them to the regulating agency.

A product called Credelio Quattro is under FDA review in 2024. This product will combine an isoxazoline compound with three other active ingredients, to give it a wider range of coverage than the company’s existing offering.

NexGard PLUS Chew for Dogs uses ingredients similar to that of Simparica Trio. It kills four ticks—one fewer than Simparica Trio and Bravecto. Nexgard PLUS’s main advantage is it protects against three species of hookworms, versus Simparic Trio’s two, and some dogs may prefer its beef flavor. But it’s more expensive, and it can’t be used on dogs weighing less than 4 pounds (versus Simparica Trio’s 2.8-pound minimum dog weight).

The Credelio Chewable Tablet for Dogs is made of another isoxazoline compound, lotilaner, that effectively kills fleas and ticks on your pet and in your home. But it doesn’t cover heartworm and intestinal parasites. It has similar coverage as the Bravecto Chew for Dogs, but it must be given every month, and it doesn’t claim to kill the Asian longhorned tick.

Bravecto Topical Solution for Dogs is a topical with the same ingredients as our Bravecto Chew for Dogs pick. This topical treatment is a little cheaper and also lasts for 12 weeks. However, we’ve found that chewable tablets are easier to give dogs, so there’s no other benefit here unless your dog refuses oral treatments.

Bravecto 1-Month Chews for Dogs is a monthly chew that can be given to puppies as young as eight weeks. But our pick, Simparica Trio, can also be given at that age, and it covers more parasites. Plus, like the Bravecto topical, this chew doesn’t tackle intestinal parasites.

Revolution Topical Solution for Dogs kills fleas and internal parasites, but it protects against only one species of tick—the fewest compared with protection from all of the combination treatments we looked at.

Frontline Plus Flea and Tick Spot Treatment for Medium Dogs is less expensive than most of our picks for dogs, and it’s available over the counter. But it’s a topical that stays on the surface of the skin and coat; it doesn’t work systemically, like most of our other picks. So it can leave some spots unprotected.

The NexGard Chewables for Dogs offer similar coverage as the Bravecto Chew for Dogs, our also-great pick. But the NexGard chewable must be given monthly, as opposed to eight to 12 weeks for Bravecto. Still, this product offers robust tick coverage, so it can be a good option, especially if your dog prefers NexGard’s flavor.

Bravecto Topical Solution for Cats lasts for 12 weeks—four weeks longer than the Plus version—but it doesn’t cover as many parasites. It’s still a great option if your cat will let you apply a separate worm treatment.

NexGard COMBO Topical for Cats is similar to the Bravecto Plus and Revolution Plus, but it covers fewer ticks.

Advantage II Flea Spot Treatment for Cats kills only fleas. We think combination products are more convenient, and tick coverage is a must in many parts of the country.

Credelio Chewable Tablets for Cats is a good option if your cat is unusual and prefers an oral treatment to a topical, but it protects against one type of tick only, and it doesn’t work against internal parasites. So you’ll still need to treat your cat for heartworm, hookworm, and roundworm.

The article was edited by Harry Sawyers. A previous version of this guide was written by Kaitlyn Wells.

Remmington Belford, spokesperson for the U.S. Environmental Protection Agency, email interview, May 1, 2024

Chris Adolph, DVM, MS, DACVM (parasitology), senior veterinary specialist—parasitology at Zoetis Inc., video interview, April 22, 2024

Aly Cohen, DVM, extension veterinarian at the Riney Canine Health Center, clinical instructor at Cornell’s Maddie’s Shelter Medicine Program, Cornell University College of Veterinary Medicine, phone interview, April 15, 2024

Susan Little, DVM, PhD, DACVM (parasitology), professor of parasitology at the Center for Veterinary Health Sciences at Oklahoma State University, phone interview, April 12, 2024

Michael Rust, distinguished professor of graduate studies, Department of Entomology at UC Riverside, phone interview, April 11, 2024

Jennifer Gervais, PhD, pesticide specialist at the National Pesticide Information Center, Department of Environmental and Molecular Toxicology, email interview, February 11, 2021

Ken Labbe, spokesperson for the U.S. Environmental Protection Agency, email interview, February 11, 2021

Douglas Kratt, DVM, president of the American Veterinary Medical Association, email interview, January 29, 2021

Tierra Price, DVM, MPH, a spay-neuter surgeon and founder of the BlackDVM Network, phone interview, February 10, 2021

Jennifer Welser, DVM, chief medical officer at Mars Veterinary Health, email interview, February 5, 2021

Tina Wismer, DVM, MS, DABVT, DABT, senior director of the ASPCA Animal Poison Control Center, email interview, January 29, 2021

Mel Plaut is a staff writer covering pets at Wirecutter. They developed a special affinity for animals at an early age, when every stray cat and runaway dog ended up at their family’s doorstep. Their writing has appeared in The New York Times, the New York Daily News, USA Today, HuffPost, NPR’s All Things Considered, and others.

by Annemarie Conte and Doug Mahoney

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The 8 Best Flea and Tick Treatments for Cats and Dogs in 2024 | Reviews by Wirecutter