How Trifexis Works for Your Dog’s Protection

Trifexis is a popular and effective oral medication for dogs that offers a three-in-one solution against fleas, heartworms, and several intestinal parasites. It’s essential to understand how Trifexis works to ensure your dog receives the right protection from these parasites. In this article, we will discuss the various ways Trifexis works to keep your furry friend healthy and safe.

Eliminating Fleas

One of the primary functions of Trifexis is to kill and prevent flea infestations in dogs. The active ingredient responsible for this is Spinosad, which targets the nervous system of fleas, causing paralysis and eventually death. Trifexis starts killing fleas within 30 minutes of administration and eliminates 98-100% of fleas within four hours. It also prevents new infestations by killing fleas before they lay eggs, breaking the flea life cycle.

Preventing Heartworm Disease

Trifexis also protects your dog from heartworm disease caused by the parasitic worm Dirofilaria immitis. The active ingredient Milbemycin Oxime prevents heartworm infections by killing the larval stage of the heartworm, which is transmitted through mosquito bites. Administering Trifexis monthly ensures continuous protection against heartworm disease for your dog.

Treating and Controlling Intestinal Parasites

In addition to combating fleas and heartworms, Trifexis also targets several common intestinal parasites. Milbemycin Oxime is effective against roundworms, hookworms, and whipworms. These parasites can cause gastrointestinal issues, weight loss, and other health complications in dogs. By killing and controlling these parasites, Trifexis helps maintain your dog’s overall health.

Tips for Administering Trifexis

  • Consult your veterinarian before starting Trifexis to ensure it’s the right choice for your dog.
  • Administer Trifexis once a month, preferably on the same day each month.
  • Give Trifexis with food to ensure proper absorption and minimize potential side effects.
  • Observe your dog for any adverse reactions after administering Trifexis, such as vomiting or lethargy, and consult your veterinarian if needed.
  • Keep in mind that Trifexis does not protect against ticks. If ticks are a concern in your area, ask your veterinarian about additional tick protection options.


Trifexis is a powerful and convenient solution for protecting your dog from fleas, heartworms, and common intestinal parasites. Understanding how it works can help you make informed decisions about your dog’s health and ensure they receive the best possible protection. Always consult your veterinarian before starting or changing your dog’s parasite prevention regimen.

FAQs about Trifexis

How Does Trifexis Work?

Trifexis combines two active ingredients: milbemycin oxime and spinosad. Milbemycin oxime works by disrupting the nerve transmission of worms, which ultimately leads to their paralysis and death. Spinosad, on the other hand, targets fleas by causing excessive excitation in their nervous system, which results in paralysis and death. When given to dogs once a month, Trifexis works effectively to prevent, treat, and control various parasites.

How Long Does it Take for Trifexis to Work?

Trifexis starts working quickly after administration. It begins killing fleas within 30 minutes, and studies have shown that it can kill 100% of fleas within four hours. For the prevention and treatment of heartworm and intestinal parasites, Trifexis should be given consistently every month to maintain its efficacy.

Can My Dog Still Get Fleas with Trifexis?

While Trifexis is highly effective at killing fleas, it’s important to note that no medication can provide 100% protection. However, when administered correctly and consistently, Trifexis can significantly reduce the risk of flea infestations in your dog.

Does Trifexis Kill Flea Eggs?

Trifexis does not directly kill flea eggs. However, by killing adult fleas, it effectively breaks the flea life cycle, preventing the production of new eggs and larvae. This helps to reduce the risk of future infestations.

Is Trifexis 100% Effective?

Although Trifexis is highly effective, no medication can guarantee 100% protection against all parasites. To maximize the efficacy of Trifexis, it’s essential to administer the correct dosage consistently every month and follow your veterinarian’s recommendations.

Does Trifexis Kill Ticks?

Trifexis does not provide protection against ticks. If tick protection is needed, you should discuss additional options with your veterinarian, such as using a tick collar or a separate tick prevention medication.

Does Trifexis Kill Tapeworms?

Trifexis is not effective against tapeworms. If you suspect your dog has a tapeworm infection, consult with your veterinarian for appropriate treatment options.

What Worms Does Trifexis Not Kill?

While Trifexis is effective against adult hookworms, roundworms, and whipworms, it does not protect against tapeworms, lungworms, or heartworm microfilariae. If your dog is at risk for these parasites, discuss additional preventative measures with your veterinarian.

How Do I Administer Trifexis to My Dog?

Trifexis is an oral medication that should be given to your dog once a month with a full meal. This helps ensure proper absorption of the active ingredients and reduces the risk of gastrointestinal side effects. To administer Trifexis, you can either offer it directly to your dog as a treat or hide it in a piece of food to encourage consumption.

What Are the Possible Side Effects of Trifexis?

As with any medication, there may be potential side effects when using Trifexis. Some common side effects include vomiting, diarrhea, lethargy, loss of appetite, and itching or redness of the skin. In rare cases, more severe side effects such as seizures or allergic reactions can occur. If you notice any concerning symptoms in your dog after administering Trifexis, contact your veterinarian immediately.

Is Trifexis Safe for All Dogs?

Trifexis is generally safe for dogs eight weeks of age and older, weighing at least five pounds. However, it is not recommended for dogs with a known history of seizures or those allergic to the active ingredients. Additionally, Trifexis should be used with caution in breeding, pregnant, or lactating dogs, as its safety has not been fully evaluated in these groups. Always consult your veterinarian before starting Trifexis or any new medication for your dog.

Can Trifexis Be Used with Other Flea and Tick Products?

It is essential to consult with your veterinarian before using Trifexis in combination with other flea and tick products. Some medications may interact negatively with Trifexis or increase the risk of side effects. Your veterinarian will be able to provide guidance on the best course of action for your dog’s specific needs.

How Can I Ensure Trifexis Remains Effective?

To maintain the effectiveness of Trifexis, it’s crucial to administer the correct dosage consistently every month, year-round. Missing doses or not providing the medication with a full meal can reduce its efficacy. Additionally, it’s essential to store Trifexis at room temperature, away from moisture and heat, as improper storage can affect the medication’s potency.

What Should I Do If My Dog Misses a Dose of Trifexis?

If your dog misses a dose of Trifexis, administer the missed dose as soon as you remember, and then resume the regular monthly schedule. If it’s almost time for the next dose, skip the missed dose and continue with the regular schedule. Do not give your dog two doses at once. If you’re unsure about the missed dose, consult your veterinarian for guidance.

Do I Need a Prescription for Trifexis?

Yes, Trifexis is a prescription medication and requires authorization from a licensed veterinarian. Your veterinarian will determine if Trifexis is the right choice for your dog based on their medical history, age, weight, and potential risk factors.

What Should I Do If My Dog Experiences an Overdose of Trifexis?

If you suspect your dog has ingested more than the recommended dose of Trifexis, contact your veterinarian or an emergency animal clinic immediately. Signs of an overdose may include severe vomiting, tremors, seizures, or difficulty breathing. Early intervention is crucial in managing an overdose and minimizing the risk of severe complications.

How Do I Know If Trifexis Is Working for My Dog?

To determine if Trifexis is effectively working for your dog, monitor for a decrease in flea infestations and the absence of intestinal parasites in their stool. A reduction in flea-related issues such as scratching, skin irritation, or hair loss is a good indication that Trifexis is working. Additionally, your veterinarian can perform tests to ensure your dog remains heartworm-free and free of intestinal parasites.

Can Trifexis Be Used in Cats?

Trifexis is specifically formulated for dogs and should not be used in cats. There are alternative flea, heartworm, and intestinal parasite medications available for cats, and it is crucial to consult with your veterinarian to determine the most suitable and safe option for your feline companion.

How Should I Dispose of Unused or Expired Trifexis?

Dispose of unused or expired Trifexis by following the disposal instructions provided on the product packaging, or consult with your veterinarian or local waste disposal facility for guidance. Do not flush Trifexis down the toilet or pour it down the sink, as this can contaminate water sources and harm aquatic life.

Can My Dog Swim or Bathe After Taking Trifexis?

Since Trifexis is an oral medication, it is not affected by swimming or bathing. Your dog can safely participate in water-related activities without reducing the efficacy of the medication.

Is Trifexis Safe to Use in Dogs with Food Allergies?

Trifexis is a beef-flavored chewable tablet, and some dogs with food sensitivities or allergies may have a reaction to the flavoring. If your dog has a known beef allergy or food sensitivity, consult with your veterinarian to determine if Trifexis is suitable for your pet or if an alternative medication is necessary.

What Should I Do If My Dog Vomits Shortly After Taking Trifexis?

If your dog vomits within an hour of taking Trifexis, it is possible that the medication was not fully absorbed. Contact your veterinarian for guidance on whether to administer another dose or wait until the next scheduled dose. To minimize the risk of vomiting, always give Trifexis with a full meal.

Can My Dog Develop Resistance to Trifexis?

There is currently no evidence to suggest that dogs can develop resistance to Trifexis. However, to maintain its effectiveness, it is crucial to administer the medication consistently every month and follow the appropriate dosage guidelines based on your dog’s weight.

What Happens If My Dog Is Exposed to Ticks While on Trifexis?

Trifexis does not provide protection against ticks. If your dog is at risk of tick exposure, you may need to use an additional tick prevention product alongside Trifexis. Consult your veterinarian for recommendations on the most suitable tick prevention options for your dog. Regularly check your dog for ticks and remove them promptly to reduce the risk of tick-borne diseases.

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