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Is it safe to combine Trifexis and Simparica for my dog?

Updated On September 23rd, 2025

Pet's info: Dog | Australian Shepherd - miniature | Male | neutered | 1 year and 2 months old | 24.7 lbs

I have a 14-month-old mini Australian Shepherd who tested clear on the MDR1 gene mutation, no known health issues. He’s taken Trifexis for 11 months for flea/heartworm prevention, Simparica added 3 months ago for tick prevention. Meds are given with meals 1-2 wks apart. We live in an area where heartworm & ticks are a problem so I need year-round preventives. Are there any known contraindications with this combo, or other meds that provide good protection with minimal side effects?

2 Answers

Most Helpful Answer

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Answered By Juliana, DVM

Veterinarian

Published on February 24th, 2018

It is ok to give trifexis and simparica together (staggered by 2 weeks is great). Both of those medications will protect against fleas so there is some overlap with that. If you want to streamline how many medications you are giving Dakota monthly, Another option would be to use sentinel or interceptor instead of the trifexis and give with that with simparica monthly. These products contain the same heart worm preventative (milbemycin) as trifexis but do not contain any medication to kill adult fleas. (Trifexis contains both the milbemycin for heart worm prevention and Spinosad for fleas). That way you would be giving one medication for heart worm prevention (sentinel or interceptor ) and one for flea and tick prevention (simparica). Another option is to continue trifexis and add in a tick collar (such as the preventic collar or the seresto collar). I know there are so many products and options it is confusing ! Let us know if you have any other questions. And great job with preventative care.

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Other Answers

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    Answered By Laura Johnson VMD

    Veterinarian

    Published on December 23rd, 2019

    Hi, thanks for using Petco Pet Education Center, formerly Petcoach! Gump should be fine as long as each drug was correct for his weight. Simparica is only for fleas and ticks. Trifexis is for heartworm prevention, intestinal parasites and fleas. It doesn't cover ticks. It is common to use TWO drugs to prevent fleas, ticks, intestinal parasites and heartworm and there is not a single product that gets everything. I hope this helps and I wish you a happy holiday!

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    1Pet Parents found this answer helpful

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