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Trifexis vs Heartgard Plus: We Asked a Vet (2023 Update)

Dr. Joanna Woodnutt Profile Picture

By Dr. Joanna Woodnutt

Review Summary

Both Trifexis and Heartgard Plus provide effective protection against heartworm infection. They both require monthly administration in the form of a beef-flavored chew tablet and are available with a veterinary prescription. Trifexis and Heartgard Plus can only be given to your dog once he has a negative heartworm test, otherwise, they could prove dangerous.

Both products also offer treatment against hookworm and roundworms. Trifexis has the added benefit of also providing flea treatment and protection, as well as treating for whipworm. This Is, however, reflected in the price as it is significantly more expensive than Heartgard Plus.

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At a Glance

Let’s look at the key points of each product:

trifexis vs heartgard plus

  • Kills fleas and prevents flea infestation
  • Prevents heartworm disease
  • Treats and controls hookworm, roundworm, and whipworm
  • 1 beef-flavored tablet given once a month
  • Only available by veterinary prescription
Heartgard Plus
  • Prevents heartworm disease
  • Treats and controls hookworm and roundworm
  • 1 beef-flavored tablet given once a month
  • Only available by veterinary prescription

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Overview of Trifexis

Trifexis for dogs (10.1-20 lbs)

  • Kills and controls fleas and whipworm as well as heartworm, roundworm, and hookworm
  • It’s a flavored chew tablet, which makes it easy to administer to most dogs
  • It starts killing fleas in just 30 minutes
  • It’s available in 5 different strengths to suit dogs of different weight ranges
  • Puppies need to be at least 8 weeks old
  • Dogs need to weigh at least 5 pounds
  • It might be difficult to administer to dogs that are fussy eaters or do not take tablets well.
  • As with any medication, Trifexis may cause side effects in a small number of dogs, the most common being vomiting, itching, and lethargy

Overview of Heartgard Plus

Heartgard Plus for dogs (26-50 lbs)

  • It’s a flavored chew tablet, so it’s easy to administer to most dogs
  • It can be used in puppies from just 6 weeks of age
  • There is no minimum weight before it can be used
  • It’s available in 3 different strengths to suit dogs of different weight ranges
  • It doesn’t treat fleas or whipworm
  • It might be difficult to administer to dogs that are fussy eaters or do not take tablets well
  • As with any medication, Heartgard Plus may cause side effects in a small number of dogs, the most common being vomiting, diarrhea, and lethargy
  • It contains Ivermectin which certain dogs of the Collie breed can be more sensitive to (although Heartgard Plus has been shown to be safe for use in Collies)

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How do they compare?

Active ingredient

The active ingredients in Trifexis are spinosad and milbemycin oxime. The active ingredients in Heartgard Plus are ivermectin and pyrantel. These all belong to different classes of drugs.

Target parasites

Both Trifexis and Heartgard Plus kill:
  • Dirofilaria immitis larvae (immature heartworm)
  • Toxocara canis and Toxascaris leonina (roundworms)
  • Ancylostoma caninum (a hookworm)
In addition to this, Trifexis also kills:
  • Ctenocephalides felis (cat flea)
  • Trichuris vulpis (whipworm)
Heartgard Plus does not kill either of these but does kill 2 additional types of hookworm:
  • Uncinaria stenocephala and Ancylostoma braziliense.

Neither product is licensed to treat existing heartworm infections and dogs should be tested for heartworm infection before being treated with either product.

Duration of action

Both products provide one month of protection against their respective parasites.


Both Trifexis and Heartgard Plus are beef-flavored chewable tablets.


Trifexis can be used for dogs weighing 5 pounds or greater.  There is no lower weight limit for Heartgard Plus. For both products, there are different weight bands of treatments depending on the weight of the animal to be treated. There are 5 different weight ranges of Trifexis and 3 different weight ranges of Heartgard Plus.


Heartgard Plus is significantly cheaper than Trifexis, however, bear in mind that you would need to purchase an additional product for flea control to use alongside Heartgard Plus.

chewable tablets for dogs
Image Credit: Merrimon Crawford, Shutterstock

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What the Users Say

We’ve done some research to find out what the people who have used these products on their dogs have to say about them. For the most part, the feedback for both products is positive and nearly everyone comments on how Trifexis and Heartgard Plus are very effective. A lot of people like the fact that they are tablets and are less messy than applying a topical spot-on to their dog.


Quite a few people have commented that their dog doesn’t like the taste of Trifexis and they find it difficult to administer, even disguised in food. Many users say that it is very expensive but is worth the investment as they have not had any problems with fleas or heartworm since they’ve been using it.

There are quite a few mentions of side effects after Trifexis has been given, the most common ones being lethargy and sickness. A couple of users have commented that it’s disappointing that Trifexis doesn’t also protect against ticks. All that said, there are a lot of very positive reviews with most people saying how effective Trifexis is and how their dog hasn’t had any fleas or heartworm infections since they started using it.

Heartgard Plus

Most people say that Heartgard Plus works very well and that their dog loves the taste, making administration very easy. There are very few people reporting any side effects but there is the odd comment that says their dog has vomited after taking it. Most people, however, say that they have not seen any side effects with Heartgard Plus, despite some dogs experiencing side effects with other products. A lot of users comment that it is much more affordable than other heartworm preventatives.

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It is difficult to comment on which of these products is better as they offer different benefits and drawbacks. Trifexis has the added benefit of flea protection which Heartgard Plus doesn’t, and this may make it more convenient for some people. However, Trifexis is more expensive than many other parasite protection products, including Heartgard Plus.

Heartgard Plus can be used in smaller dogs than Trifexis can, which makes it a good option for tiny puppies and miniature breeds in particular. Both treatments are highly effective and last for a month once they have been given. Each product will carry different advantages for different pets and owners depending on their circumstances. Always be guided by your veterinarian when it comes to choosing the best parasite treatment for your pet as different products may be more or less suitable for different dogs.

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