Trifexis® (spinosad + milbemycin oxime) for Dogs: Frequently Asked Questions
Q: What is Trifexis?
Trifexis is a monthly chewable tablet for dogs. Trifexis kills fleas and prevents flea infestations, treats and controls hookworms, whipworms and roundworms, and prevents heartworm disease. Trifexis is for use in dogs and puppies 8 weeks of age or older and 5 pounds of body weight or greater. If you do not administer Trifexis monthly throughout the year, the final dose must be given no fewer than three months following the last exposure to mosquitoes.
Q: What are the active ingredients in Trifexis chewable tablets?
Spinosad and milbemycin oxime are the two active ingredients in Trifexis.
Q: Is Trifexis FDA approved?
Yes, Trifexis is a prescription product approved by the FDA and should be obtained only through a licensed veterinarian with whom you have a proper vet-client-patient relationship (VCPR).
Q: Is Trifexis safe?
Trifexis is approved by the Food and Drug Administration (FDA) for use in dogs and puppies 8 weeks of age and greater, and 5 pounds of body weight or greater. To receive FDA approval, Trifexis was tested in hundreds of dogs and detailed clinical reports were submitted for intense review. Since the product launched, Trifexis has been prescribed by veterinarians to millions of dogs around the world.1 Adverse events are reported to the FDA, and concerns are thoroughly investigated.
You should discuss the use of Trifexis with your veterinarian prior to use if your dog has a history of epilepsy (seizures). Puppies less than 14 weeks of age may experience a higher rate of vomiting.
Q: If spinosad kills fleas, how is it safe for my dog?
Trifexis is a safe product when used according to label directions. The active ingredient, spinosad, is produced by a bacterium first isolated from natural sources (a soil sample collected in the Caribbean). Spinosad, an active ingredient in Trifexis, demonstrates selective toxicity to the flea’s nervous system, allowing safe use in mammals. This selectiveness is due to differences in insect versus vertebrate (mammalian) nervous systems. However, as with all medications, sensitivities due to individual animal variation can occur.
Q: What side effects might occur with Trifexis?
As with all medicines, sometimes side effects may occur. In some cases, dogs vomited after receiving Trifexis. If vomiting occurs within an hour of administration, redose with another full dose. During field studies, no severe or prolonged vomiting occurred. Additional adverse reactions observed in the clinical studies were itching, decreased activity, diarrhea, inflammation of the skin, redness of the skin, decreased appetite and redness of the ear. All reactions were regarded as mild.
Q: How well does Trifexis work?
- In a well-controlled laboratory study, Trifexis was 100% effective against induced heartworm infections when administered for 3 consecutive monthly doses. Two consecutive monthly doses did not provide 100% effectiveness against heartworm infection.
- In well-controlled laboratory studies, a single dose of Trifexis at labeled dose was effective in removing roundworms, hookworms and whipworms.
- In a well-controlled laboratory study, spinosad alone began to kill fleas 30 minutes after administration and demonstrated 100% effectiveness within 4 hours.
Spinosad kills fleas before they can lay eggs. If a severe environmental infestation exists, fleas may persist for a period of time after dose administration due to the emergence of adult fleas from pupae already in the environment. In field studies conducted in households with existing flea infestations of varying severity, flea reductions of 98.0% to 99.8% were observed over the course of 3 monthly treatments with spinosad alone. Dogs with signs of flea allergy dermatitis showed improvement in erythema, papules, scaling, alopecia, dermatitis/pyodermatitis and pruritus (itching) as a direct result of eliminating the fleas.
Q: What is the most common adverse event with Trifexis?
The most frequently reported adverse reaction in dogs in the Trifexis chewable tablets group was vomiting.
Average Monthly Rate (%) of Dogs With Adverse Reactions
Trifexis Chewable Tablets2
Active Control Tablets2
2n=176 dogs for Trifexis and n=176 for Active control
The most common adverse reactions based on post-approval adverse drug event reporting are vomiting, lethargy, itching, and loss of appetite.
Q: Can I submit questions I have about Trifexis via Twitter or Social Media?
Because of FDA regulations regarding communications to the public, including social media interactions like Facebook and Twitter, Elanco is not able to respond to posts or queries made on third-party sites or in public forums. For technical questions or to report a suspected adverse drug reaction, it is important that you contact Elanco Animal Health at 1-888-545-5973. Additional information can be found at www.trifexis.com. Alternatively, suspected adverse drug reactions may be reported to FDA at 1-888-FDA-VETS or http://www.fda.gov/AnimalVeterinary/SafetyHealth/ReportaProblem/ucm055305.htm
Q: What should I discuss with my veterinarian regarding Trifexis for my dog?
Your veterinarian is your dog’s healthcare expert and can make the best recommendation for medications for your dog. This includes the prevention, control and/or treatment of parasites such as fleas, heartworms and intestinal parasites that may cause conditions that include flea allergy dermatitis, anemia, heart disease and other parasite-related problems. Key points of your discussion may include the following:
- As with other heartworm preventatives, dogs should be tested for heartworm before beginning treatment with Trifexis.
- If a dose is missed and/or monthly intervals between doses is exceeded, immediately give Trifexis with food and resume monthly dosing. This practice will minimize the opportunity for heartworms to grow. Also, continuing normal monthly dosing will allow you to gain control of any flea or intestinal parasites that might have infected your dog.
- To minimize the likelihood of fleas continuing to jump onto your dog, it is important to treat all household pets with an approved flea protection product.
- Trifexis tablets are not for use in humans. Like all medications, keep Trifexis out of the reach of children.
Q: Why has my veterinarian prescribed Trifexis?
Your veterinarian has prescribed Trifexis as a way of preventing your dog from developing problems caused by infection with three commonly occurring parasite categories. Heartworm infection can make dogs very sick and can even be fatal. This parasite is spread to dogs by mosquitoes. Trifexis can prevent flea infestations from becoming established, and can also remove any fleas that are on your dog at the time of treatment. Trifexis will also treat and control common adult intestinal worm infections (roundworms, hookworms and whipworms).
Q: What are some of the benefits of Trifexis?
Trifexis is novel in several ways:
- Trifexis is the first oral monthly product that rapidly kills fleas and also is effective in preventing heartworm disease and treatment and control of adult hookworm (Ancylostoma caninum), adult roundworms (Toxocara canis and Toxascaris leonina) and adult whipworm (Trichuris vulpis) infections in dogs and puppies 8 weeks of age or older.
- Trifexis is approved by the FDA.
- Spinosad, one of the ingredients in Trifexis, begins to kill fleas 30 minutes after administration with 100% effectiveness within 4 hours, in a well-controlled laboratory study.
- Trifexis continues to kill fleas for a full month after treatment.
- Trifexis is available in five strengths: 140mg, 270mg, 560mg, 810mg, and 1620mg. Each tablet is formulated to provide a minimum dosage of 13.5mg/lb (30mg/kg) spinosad and 0.2 mg/lb (0.5 mg/kg) milbemycin oxime according to body weight.
Q: How can I purchase Trifexis?
Trifexis is a prescription product that should be purchased only from a licensed veterinarian.
Q: How should I give Trifexis to my dog?
Give Trifexis with food for maximum effectiveness. Trifexis is a chewable tablet and may be offered as a treat. Consult your veterinarian regarding the need for year round administration of Trifexis. To help you remember the monthly dosing schedule, stick-on labels are included for your calendar.
Q: What is the flavoring in Trifexis tablets?
The flavoring in Trifexis comes from artificial beef flavoring made from pork-based proteins and hydrolyzed soy.
Q: Should I give Trifexis each month all year round?
Consult your veterinarian regarding the need for year-round use of Trifexis. If you do not administer Trifexis monthly throughout the year, the final dose must be given no fewer than three months following the last exposure to mosquitoes.
Q: What about ticks?
Trifexis is not labeled to kill or repel ticks. Trifexis is labeled for the prevention of heartworm disease and to kill adult fleas, adult hookworms, adult roundworms and adult whipworms. There are no known contraindications between Trifexis and medications commonly used against ticks.
Q: Will Trifexis kill heartworms?
Trifexis prevents heartworm disease by killing certain stages that develop after an infected mosquito bites a dog. As with other heartworm preventives, Trifexis does not kill adult heartworms. Speak to your veterinarian about treatment options if your dog is diagnosed with an adult heartworm infection.
Q: Why does my dog need a heartworm test before starting Trifexis?
Before starting Trifexis, dogs should be tested for heartworms because giving preventatives to dogs that have adult heartworm infection can be harmful or fatal to the pet. If infected, your veterinarian may decide to treat your dog with a heartworm adulticide.
Heartworms produce millions of microscopic “baby” heartworms, called microfilaria. In dogs carrying a high number of circulating microfilariae, mild, brief hypersensitivity reactions such as labored respiration, vomiting, salivation, and lethargy have been noted in some dogs treated with milbemycin oxime. These reactions are thought to be caused the by release of protein from the dead or dying microfilariae.
Q: Which life cycle phase for the heartworm does Trifexis control?
Trifexis acts in the same way as other monthly heartworm preventives by killing L3 and L4 larval stages before they molt to the final, adult stage.
Q: Will my dog still need to be tested for heartworm infection while taking Trifexis?
You should speak to your veterinarian about the frequency of heartworm testing while your dog is taking Trifexis.
Q: How do I switch to Trifexis from another heartworm preventive?
Follow the advice of your veterinarian about switching heartworm preventives.
Q: Do I have to give Trifexis with food?
Administer Trifexis with food for maximum effectiveness.
Q: What if I give more than the prescribed amount of Trifexis to my dog?
Contact your veterinarian as soon as possible if you believe your dog has ingested more than the recommended dose of Trifexis. In a study in which dogs were dosed at 1, 3, and 5 times the upper half of the recommended dose, dogs exhibited vomiting, tremors, decreased activity, salivation, coughing and vocalization.
Q: Should I restrict either my dog's activity or contact with my dog after the tablet is consumed?
You may maintain normal activities and interactions with your dog.
Q: How quickly will Trifexis kill fleas?
In a laboratory study of spinosad alone, an active ingredient of Trifexis, spinosad started to kill fleas within 30 minutes and killed 100% of the fleas within 4 hours. Trifexis kills fleas before they can lay eggs.
Q: Does seeing fleas on my dog mean that the treatment is not working?
Trifexis kills fleas before they can lay eggs when used monthly according to the label directions. Remember that all animals in the household should be treated with an approved flea product to help control the flea population. Your dog can continue to be exposed to the fleas that live in the environment. When fleas jump onto your dog, they will be killed by Trifexis. If within a month after your dog receives Trifexis you see fleas on your dog, it is most likely that these are new fleas. These new fleas will be killed before they can produce eggs that contaminate the environment. Continued monthly use of Trifexis can prevent any new infestations.
Q: What if I see worms in my dog's stool during the month after administration of Trifexis?
Trifexis is indicated to treat and control intestinal parasite infections of adult hookworms, roundworms and whipworms. In occasional cases, it is possible that the action of Trifexis in killing the intestinal worms will lead to the dog expelling them in the stool. If you have questions, consult with your veterinarian for measures you can take to prevent a reinfection with intestinal parasites.
Q: My dog has tapeworms. Will Trifexis get rid of those?
No, Trifexis will not treat a tapeworm infection. Trifexis is indicated for the prevention of heartworm disease, for the prevention and treatment of flea infestations and the treatment and control of adult hookworm, adult roundworm and adult whipworm infections in dogs and puppies 8 weeks of age or older, and 5 pounds of body weight or greater.
Q: Is it safe to give my breeding dogs Trifexis?
Ask your veterinarian about the use of Trifexis prior to use in breeding females. The safe use of Trifexis in male dogs intended for breeding has not been evaluated.
Q: Can other medications be given while my dog is taking Trifexis?
Yes, Trifexis has been given safely with a wide variety of products and medications. However, there is a label warning that serious adverse reactions have been reported following simultaneous extra-label use of ivermectin with spinosad alone, one of the components of Trifexis. Your veterinarian should be made aware of all products that you administered and/or intend to administer to your dog.
Q: Can Trifexis be used in conjunction with amitraz, which is found in certain products indicated for activity against ticks?
Trifexis is safe for use with amitraz if both are used according to label directions. Please consult your veterinarian for further dosing information.
Q: Can Trifexis be given if my dog has allergies?
Trifexis contains some hydrolyzed soy and is flavored with artificial beef from a pork-based protein. The amount of hydrolyzed soy in Trifexis is comparable to the amount of the hydrolyzed soy in hypoallergenic diets. If your dog is allergic to soy or pork, you might consider other flea treatment and heartworm and intestinal parasite prevention products. Please discuss these options with your pet’s veterinarian.
Q: Can Trifexis be given to cats?
No. Trifexis is not approved for use in cats. Trifexis was developed exclusively for administration to dogs. If you also need flea control for your cat, Elanco offers a great choice for flea control for cats.
Q: Can Trifexis tablets be crushed and put in food?
We did not conduct any studies where a crushed Trifexis tablet was added to food and fed to a dog. Given our knowledge of spinosad and milbemycin oxime, it should be stable if the tablet is crushed and consumed right away. The stability in food over any significant period of time, however, cannot be guaranteed. So it is best to make sure your dog eats the meal immediately.
Q: The package reads chewable. What if my dog swallows the tablet whole?
Given our knowledge of spinosad and milbemycin oxime, Trifexis will be effective if the tablet is consumed in whole (not chewed).
Print the client information sheet for Trifexis®