Get

In Your Inbox

Dogster is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

Trifexis for Dogs: Our Vet Explains the Uses & Efficacy

Man giving pill to dog

There are many different preventative options on the market that may be appropriate for preventing fleas, heartworms, and other parasites in your dog. Based on your dog’s age and lifestyle, there may be more than one option that would be recommended for them. One option is a product called Trifexis. It’s made by the Elanco Company and was one of the first three-in-one oral products on the market. In this article we’ll discuss Trifexis, and why it may or may not be a good preventative option for your dog.

Dogster divider_v2_NEW_MAY_24_

What Is Trifexis?

Trifexis is a prescription preventative that has been approved for dogs. It is not available over the counter (OTC). Trifexis’ two active ingredients are Spinosad and Milbemycin Oxime. Spinosad is an insecticide that is made from natural components of a soil bacterium. This ingredient in Trifexis is what helps to kill and prevent flea infestation on your dog. Milbemycin Oxime is an anthelmintic that has efficacy against the development of heartworms, hookworms, roundworms, and whipworms.

Trifexis is labeled for the treatment and prevention of fleas, prevention of heartworm disease, and the treatment and prevention of hookworms, roundworms and whipworms. It’s important to know that Trifexis does not provide any coverage to help prevent or kill ticks.

person giving tick and flea medicine to a white maltese dog
Image Credit: Tanya Dol, Shutterstock

How Is Trifexis Given?

Trifexis is a chewable, beef-flavored tablet that has to be given by mouth. The product is to be given based on your dog’s current weight. There are different sizes of the mediation based on an animal’s weight, with each tablet containing different amounts of the above ingredients based on body weight. It’s important that you have a recent, accurate weight on your dog, and you give the appropriately sized tablet. Dosing your dog either too high or too low may cause the medication either to not be effective or have potentially negative side effects.

The tablet is given once every 30 days for both treatment and prevention. One of the most common side effects we can see with Trifexis is vomiting and/or an upset stomach. Therefore, it’s always recommended to give this medication with food. Even though the tablet is reportedly flavored, many dogs do not like the taste of Trifexis. Many owners have reported that they often need to hide Trifexis in copious amounts of cheese, peanut butter, or even just pill their dog due to the taste.

What Happens if You Miss a Dose?

Trifexis is effective for 30 days. If you miss a month or two, there is the possibility that your dog may become infected or infested with fleas, intestinal parasites, and/or heartworms.

Unfortunately, some of these infections may not become apparent for months. For instance, heartworm disease can sometimes take 6+ months to show up on a test. In other words, a dog that received heartworm disease from an infected mosquito over the summer may not test positive until the winter or after.

This is why it’s so important to continue giving this and any preventative on time, every month. Missing a month or two can cause not only infection or infestation but may also be difficult to diagnose due to an interrupted timeline of application.

longhaired dog scratching itself
Image Credit: ARVD73, Shutterstock

Potential Side Effects of Trifexis

The most common adverse side effect that we can see with Trifexis is vomiting. A lot of dogs also hate the taste, even though it’s beef flavored. A picky eater may not take the pill no matter how you try to hide it. Other dogs may exhibit signs of an allergic reaction such as itching, redness to the skin and ears, and lethargy. In addition to vomiting, other dogs may develop diarrhea.

In rare cases, some dogs will develop tremors, drooling, difficulty walking, disorientation, and seizure activity. These reported cases are rare but in the event they occur, your dog should be seen by a veterinarian immediately.

Dogster divider_v2_NEW_MAY_24_

Frequently Asked Questions (FAQ)

Is Trifexis Safe to Give in a Heartworm-Positive Dog?

No. Trifexis is not a recommended and/or approved product to give if your dog has already been diagnosed with heartworm disease. Trifexis helps to prevent heartworm disease, but it does not kill adult heartworms. Please contact your veterinarian to discuss other options if your dog has been recently diagnosed with heartworm disease.

Did you know you can talk to a vet online? Click on the image or button below to schedule a call: PangoVet_Mention-in-Content Savings V1


What If My Dog Is Exposed to Ticks?

Trifexis is not labeled for protection against ticks. Therefore, if your dog is outside for long periods of time, goes hiking, camping, or you just have a lot of growth in your yard, then you should speak to your veterinarian about a better product to give for tick protection.

Can I Give a Small Trifexis to My Cat?

No. This product is not approved and/or safe for cats. Please remember that cats are not small dogs and should not be given this medication.

Husky dog lying on vet table with doctor and master near by
Image Credit: Pressmaster, Shutterstock

Dogster divider_v2_NEW_MAY_24_

Conclusion

Trifexis was one of the first three-in-one preventatives on the market, helping to prevent fleas, heartworms, and intestinal parasites. Unfortunately, the product is not approved for ticks and would not be recommended for your dog if you live in an area endemic to ticks. The product is considered safe in dogs who are confirmed to be heartworm negative and should be given based on the appropriate recommended weight range. Many dogs do not like the taste of the product and can develop vomiting and diarrhea. Trifexis should be given once every 30 days in order to provide the best efficacy. Trifexis has to be prescribed by your veterinarian and cannot be purchased OTC.


Featured Image Credit: Creative Cat Studio, Shutterstock

Want content like this delivered to you?

Sign Up For Our Newsletter

News, insights, expert advice, and everything dog

* By submitting, you agree to our Terms & Conditions and Privacy & Cookies Policy.

How useful was this post?

Click on a star to rate (you can leave written feedback after clicking submit)

Help us improve Dogster for pet parents!

Your feedback really matters.

What did you like about this post? Also how can we improve it?

Join the conversation

4 Responses

  1. My dog weighs 22-24 pounds- I have continued to use the 20lb dosage as I am uncomfortable giving 40 pounds worth of meds- will it be effective like this?

    1. Hi Anna, thanks for reaching out to us. Since this is a prescription-only medication, it's really important to check in with your veterinarian to make sure you're using the right dose. Based on your dog's weight of 22-24 lbs, the correct product would be the one labeled for that weight range: 20.1 and 40 pounds. Following your vet's advice or the manufacturer's recommendation is the best way to keep your pup safe and protected. If you still feel uneasy, your vet may be able to help you calculate how to give a precise dosage for your dog's specific weight by breaking up some tablets. I hope this helps. 🙂

    1. Hi Eileen, thanks for reaching out. No, Trifexis doesn’t contain any grains. It’s not a food-based product or treat, so it doesn’t include grains like wheat, corn, or soy. That said, if your pet has specific allergies or sensitivities, it’s always a good idea to check the inactive ingredients with your vet just to be sure!

Leave a Reply

You’re very welcome to leave a comment or question. Please know that all comments must meet our community guidelines, and your email address will NOT be published. Let’s have a positive and constructive conversation.

Talk With A Vet Online

Peace of mind,
anywhere, anytime

Affordable vet advice

Top 10 Dog-Friendly Beaches in San Clemente, CA (With Pictures)

San Clemente, California, is a beach destination ideal for all types of travelers. The sun, sand, and surf make it an enjoyable place...

Is a Newfoundland Dog Hypoallergenic? Vet-Approved Facts & FAQ

Dogs have been our beloved companions for centuries, but if you’re an allergy sufferer as well as a dog lover, it is pretty...

Saint Pyrenees (Saint Bernard & Great Pyrenees Mix): Info, Pictures & Care

The Saint Pyrenees is a mixed breed with Saint Bernard and Great Pyrenees parentage. With ancestors like that, it’s no wonder that Saint...

250+ Spanish Dog Names With Meanings for Male & Female Dogs

There are many Spanish dog breeds like the Spanish Mastiff, Spanish Pointer, and Spanish Water Dog. However, Spanish dog names are not reserved...

More related

Summer Safety Tips for Dogs: 7 Vet-Verified Ways to Stay Safe

Is there any better way to enjoy the warm months of summer than with your best friend? Summer is ideal for walks in...

Can a Dog Catch a Cold from a Cat? Vet Reviewed Facts & FAQ

Cold and flu season may be winding down across the Northern Hemisphere, but we’re not out of the woods yet. Just like humans,...

Q&A with Lessons in Chemistry Author Bonnie Garmus About Six-Thirty

Six-Thirty, the rescue dog in best-selling novel Lessons in Chemistry, has a thriving fan base that’s secured his spot in the book’s 2023...

Dog Licking the Air? 12 Possible Reasons & Vet Advice on What to Do

Dogs licking air can be caused by several reasons, and some of them are normal or safe behavioral displays, while others might indicate...

Keep reading

Can Dogs Eat Yogurt? Vet-Verified Nutrition Facts & FAQ

Yogurt is one of the rare treats that blends a delicious flavor with potential health benefits. If you’re a diehard fan of the tasty dairy delight, you’ve probably wondered whether your pets could enjoy it as much as you do....

Can Dogs Eat Yogurt

Victor Dog Food vs Blue Buffalo 2025 Comparison: Pros & Cons

When it comes to choosing food for your dog, it can be confusing and difficult to choose between brands. We all want the best for our dogs, but it’s not uncommon to unintentionally select a food that isn’t appropriate for...

Dogster_Dog Food Victor VS Blue Buffalo

How to Add Grain to a Grain-Free Dog Food: 5 Vet Approved Tips

Over the last decade or so, grain-free and gluten-free diets have become increasingly popular for humans, and by extension, that popularity has trickled down into canine diets, too. However, as with the human population, provided the balance of nutrients is...

Weimaraner eating dog food

Can Dogs Eat Bratwurst? Vet-Verified Facts & FAQ

Bratwurst is a tasty sausage that goes hand-in-hand with backyard cookouts. They are easy to throw on the grill, and you can eat them easily while hanging outside and engaging in summertime activities. For those who have dogs, you may...

Can Dogs Eat Bratwurst

Can Dogs Eat Guava? Vet-Verified Nutrition Facts & FAQ

While not every kind of fruit is suitable for dogs, some are safe to feed in moderation and can even offer a nutritional boost. Guava is a tropical fruit from the Myrtle family that grows on trees. Guava is a...

Can Dogs Eat Guava

Nature’s Recipe Dog Food Review 2025: Recalls, Pros & Cons

Review Summary Introduction When you’re searching for high-quality, protein-filled dog food for your canine pal, you want only the very best. However, you also want a company that delivers on its promise to provide your pet with the most nutritional...

Dogster_Nature’s Recipe Dog Food Review

10 Best Dog Foods for Active Dogs in 2025 – Reviews & Top Picks

If you have an active dog, you may have found that you struggle with keeping weight on your dog, no matter how much you feed them. Some breeds also struggle to maintain their body weight, especially while they’re young. A...

labrador retriever eating dog food

Can Dogs Eat Pizza? Vet-Verified Nutrition Facts & FAQ

Pizza is undoubtedly a staple in the US, with more than 6,000 slices consumed in a person’s lifetime. That’s a lot of pizza! Since pizza is such an American favorite, dog owners know that pizza is a coveted food item...

Can Dogs Eat_Pizza