Heartgard vs. Trifexis: 2025 Comparison and Key Differences

If your dog has fleas (or you want to prevent him from getting fleas), you have several types of products to consider. Flea collars are the most well-known flea control product, with shampoos and spot treatments also popular. Your dog may benefit from any one of these non-prescription treatments, or from stronger prescription treatments.

Oral medications for fleas are available by prescription, but you can buy them at discounted prices online. These products eliminate the messiness of shampoos and spot treatments.

Most people find oral medications easier to administer if your pet has a moderate to a serious case of fleas.

Dogs get fleas from other animals. Your pet may get fleas from feral cats or dogs or neighbors’ pets. Your dog is more likely to get fleas if he stays in the backyard all day than if he stays inside all day. Be sure to do research and determine how your dog got fleas to prevent it from happening again.

Human visitors to your home may unwittingly carry fleas. A person may bring fleas from their pet, or from a hiking trip. A quick visit to the dog park or walk around the block may also cause your dog to contact fleas.

What to Look for in a Good Flea Treatment

Over the counter flea treatments for dogs ( and some prescription treatments) are available as shampoos, flea collars, spot treatments, dips, foggers, and wipes. Some products, like collars, repel ticks, and fleas. Others destroy the infant fleas, so they don’t mature to harm your dog, while others kill adult ticks and fleas.

Other brands repel or kill existing fleas and attack young fleas. Read product information to determine which product is right for your dog.

The most popular long-term flea treatments are chewable tablets. These oral medications may come in beef or chicken flavor to make them easier for dogs to consume. Several brands also treat heartworms and are sold primarily as heartworm treatments.

Broad-spectrum treatments are your best bet because they attack many flea and tick species. Ask your veterinarian about the flea and tick species in your area to ensure that you purchase the right treatment.

Pets have personalities just like people, and your dog may be impatient. Some dogs won’t stay still during spot-on application. A flea collar is a good choice for fidgety dogs. Oral medication may be the best way to treat your dog if you don’t have enough time for periodic, DIY treatment. Some tablets last for up to 12 weeks,

Don’t give you cat flea medication meant for dogs, and vice versa. Ask your vet about appropriate flea treatments for your dog or cat.

Administer medication on time and according to directions for best results. Don’t give your pet more medication at a time than prescribed, as this may cause dangerous side effects.

Heartgard vs. Trifexis Similarities

Heartgard and Trifexis are two popular oral medications for dogs.

Trifexis is an oral medication you give to your dog once a month to prevent fleas and kill existing fleas. This medication also treats heartworms, hookworms, roundworms, whipworms, and intestinal parasites. Trifexis is a combination of milbemycin oxime and spinosad. Your dog or puppy must be eight weeks or older and weigh more than five pounds to use

Heartgard prevents heartworms, hookworms, and roundworms. This medicine kills the heartworm larva. Like Trifexis, you administer this beef-flavored medication once a month.

Both beef-flavored medications are given to dogs orally once a month. If your dog has worms, you can use either one successfully as a treatment. If you have a nervous dog, and he won’t say still for spot-on treatments, either medication will work for the animal if used according to direction.

Your dog needs to be tested for fleas for heartworm before administering either medication. The animal may experience complications or side effects with either product if you administer it with confirmation of his condition from a vet.

The ingredients used in both products are considered safe – milbemycin oxime and spinosad for Trifexis, and ivermectin and pyrantel for Heartgard. Both products have limited side effects, including vomiting, diarrhea, and lethargy.

Trifexis can be used concurrently with medications for other issues. Likewise, there are no contraindications for Heartgard. Pregnant, breeding and nursing dogs can safely take both medications.

Both medications must be prescribed by a veterinarian.

Heartgard vs. Trifexis Differences

Although Heartgard and Trifexis are monthly oral medications for heartworms, there are several major differences between the two products.

Heartgard doesn’t protect your dog against fleas, and it kills larvae only. This product won’t kill existing adult heartworms caused by mosquitoes. You must give your dog this medication exactly 30 days from the last time you administered the treatment. If you give your dog the medicine on December 1, you should give him the next tablet on January 1.

If your dog has adult heartworms, you must treat her with prescription antibiotics and steroids or choose a medication that actively kills adult heartworms instead of Heartgard.

Heartgard is a combination of ivermectin and pyrantel. Trifexis contains milbemycin oxime and spinosad.

Trifexis treats fleas and heartworms, so it protects your dog against more parasites. You won’t need to buy two different medications for your pet. Trifexis also gets rid of fleas on your pet’s coat, as well as internally. This medication works within a half-hour of your dog, taking it.

The ivermectin in Heartgard has dangerous side effects, including convulsions, slow heartbeats, sudden blindness, in some breeds, like shepherds and collies. If you have a collie or shepherd, Trifexis is a safe medication.

Trifexis controls all six of the parasites that a flea/heartworm medication can treat. Heartgard only treats three, not including fleas, which are the most visible and common pests.

Heartgard vs. Trifexis Pricing Comparison

Heartgard and Trifexis are available from many sources online, including Chewy.com. We’ve included the most recent prices from Chewy in our pricing comparison. Other online markets sell these products, and the prices may be slightly higher or lower from these sources.

Heartgard

Heartgard, a heartworm only medicine, is available in six sizes for dogs and two for cats. The chewable tablets for cats in a Purple box (5-15 pounds) or a Red box (under 5 pounds). The cost is $36 for six tablets or $34 for auto-ship.

Heartgard Plus (the ivermectin and pyrantel formula) is available for dogs up to 25 pounds (Blue box). The cost is $31, $30 for auto-ship. The Green box, for 25 to 60-pound dogs, is $40; $38 for auto-ship. TheBrown box, for dogs 51 to 100 pounds, costs $49; $47 for auto-ship.

The ivermectin-only Heartgard unflavored tablets cost $32, $30 for auto-ship for the Blue box (under 25 pounds). For dogs 25 to 60 pounds, the Green Box costs $41, $39 with auto-ship. The Brown Box, for dogs 51 to 100 pounds, is $49; $47 with auto-ship.

Trifexis

Trifexis is available in five color-coded sizes. Magenta, for 5-10 pounds dogs, costs $111 for a six month supply; $104 with auto-ship.

Orange for 10.1 to 20 pound dogs, costs $115 for six months; $109 with auto-ship.

Green, for dogs weighing 20.1 to 40 pounds, costs $118 for six tablets, $112 with auto-ship.

Blue, for canines weighing 40.1 to 60 pounds, costs $120 for six tablets: $114 for auto-ship.

Brown, for dogs weighing 60.1 to 120 pounds, costs $122 for a six-month supply: $122 for auto-ship.

Even though Trifexis costs more than Heartgard, it’s a better value because it treats heartworm, hookworm and other worms as well as fleas. Even if worms are your pet’s main problem, Trifexis may be a better medication for your dog, since it treats more than one issue.

Our Review of Heartgard vs. Trifexis

Heartgard and Trifexis are administered to dogs and are usually not used for cats. Felines should be monitored for worms, but there is no treatment. If you have a cat, inoculate it against heartworms. According to package directions, you can’t use Trifexis on cats. Ask your veterinarian about using Heartgard on your pet cat.

Veterinarians like the Trifexis brand because it protects against hookworms, heartworms, whipworms, fleas, and roundworms in dogs. The extra protection afforded by Trifexis saves you the expense of buying separate worm and flea treatments for your dog.

Trifexis has few side effects, and most dogs don’t experience any problems after receiving the treatment. Heartgard has more side effects, including convulsions, ataxia, staggering, depression, and diarrhea. Heartgard doesn’t protect your dog against fleas; it only treats worms.

Our research indicates Trifexis is a better treatment for canine worms and fleas than Heartgard. Trifexis offers broad-spectrum protection for fleas, heartworms, and other types of worms. The internal and external protection it provides eliminates the need to buy one flea control product for larvae and another for adult fleas.

Nursing pups aren’t treated by this medication if their mother uses it. Pups need to take their own dose, and pups as young as six weeks can take Heartguard. Nursing dogs can take Trifexis, and pups as young as eight weeks can also take it.

If your main concern is getting rid of fleas, Trifexis is the right medicine for our pet – with extra heartworm protection.

Flea Treatment FAQs

Is one type of treatment (oral medication, flea collars, etc.) better overall than others?

The type of treatment depends on your dog, it’s size, general health, and the severity of the flea problem. Every situation is different. Ask your vet about the best treatment method.

Can you use more than one flea treatment at a time?

Avoid using two treatments at a time because pets will fare between with limited exposure to chemicals/medications. Talk to your vet if you feel the flea control product you’re using isn’t working.

You may need to work on removing flea infestations from your carpet and other areas of your home if flea treatments for your dog are ineffective.

Should I treat all my pets if only one of them has fleas?

You should treat all your pets to prevent a flea infestation from spreading. Watch all your cats and dogs for signs of flea allergies like itching and scratching. Some pets won’t scratch even if they have fleas, so treat all household pets whether they show symptoms or not.

Why is flea prevention so important?

Adult fleas spread tapeworms and harm your pets by bloodsucking. However, adult fleas only account for one to five percent of fleas. The other 95 percent of fleas are larvae, eggs, and pupae hidden in rugs, carpets, and backyards.

What can I do to ensure my dog doesn’t get fleas again?

Use a flea comb to groom him and wash him regularly with warm water and a dog shampoo or mild dish soap. Vacuum and wash your dog’s bedding regularly. Fleas congregate in carpets, so vacuum and shampoo carpets, upholstered furniture, and draperies to rid them of dirt and fleas.

Conclusion

Heartgard, as the name indicates, is perfect for treating heartworms. These real beef chewables also control hookworm and roundworm infestations. However, these chewables don’t control fleas. This prescription medication comes in two formulas – Heartgard Plus (ivermectin/pyrantel) and regular Heartgard (ivermectin).

Trifexis provides three-in-one protection from parasites. This medication prevents fleas and heartworms. This chewable tablet also prevents roundworm, hookworm, and whipworm, so it gives your pet much more protection than Heartgard.

Even though Trifexis costs more and is available just for dogs, it gets our recommendation for its broad-spectrum abilities to protect canines against several pests. You should be aware that parasites can be anywhere your dog goes, and that includes worms, fleas, and intestinal parasites. Trifexis guards against all three parasites in one medication.

Pet parents need to consider the all-around treatment capabilities of medication when comparing one brand to another. Never decide what’s best for your pet on cost alone, even if you are on a budget.

Always discuss any flea or heartworm treatment with your veterinarian before deciding on the proper medication for your pet. Monitor your pet after each dose to check for side effects, and to check on the efficacy of treatment. If the product isn’t working as well as you think it should consult your vet.