NexGard Spectra vs Simparica Trio: The Full Comparison

Two of the Best All-in-One Dog Treatments

NexGard Spectra and Simparica Trio are the two most comprehensive single-product parasite prevention options available for dogs. Both cover fleas, ticks, heartworm, and intestinal worms in one monthly chew. For US dog owners who want to simplify their parasite prevention into a single product, these two are the main contenders.

They're genuinely close. But there are meaningful differences in speed, tick species coverage, and worm coverage that could make one a better fit for your dog.

Active Ingredients

NexGard Spectra (Boehringer Ingelheim) combines afoxolaner (fleas and ticks) with milbemycin oxime (heartworm and intestinal worms).

Simparica Trio (Zoetis) combines sarolaner (fleas and ticks) with moxidectin (heartworm) and pyrantel (roundworms and hookworms).

Full Side-by-Side Comparison

The Speed Difference

This is the most practically significant difference between the two products. Simparica Trio kills fleas within 3 hours and ticks within 8 hours of the first dose. NexGard Spectra kills fleas within 8 hours and ticks within 48 hours.

For dogs living in heavily tick-endemic areas where rapid tick kill is important to minimize Lyme disease transmission risk, Simparica Trio's 8-hour tick kill (versus NexGard Spectra's 48 hours) is a meaningful advantage. Both are within the standard 24–48 hour transmission window, but Simparica Trio provides a larger safety margin.

Tick Species Coverage

Simparica Trio is FDA-approved to kill six tick species — the lone star tick, Gulf Coast tick, American dog tick, black-legged (deer) tick, brown dog tick, and Asian longhorned tick. It is the only combination chewable specifically FDA-approved to prevent Lyme disease by killing deer ticks. NexGard Spectra covers five tick species. For most dogs the difference is marginal, but in regions where the Asian longhorned tick is spreading, Simparica Trio's broader coverage is a genuine edge.

Whipworm Coverage: NexGard Spectra's Edge

NexGard Spectra covers whipworms (Trichuris vulpis) through its milbemycin oxime component. Simparica Trio does not cover whipworms. Whipworms are less common than roundworms and hookworms, but in areas where they're prevalent (particularly in humid, warm climates), this is a genuine advantage for NexGard Spectra.

If whipworm exposure is a concern in your area, NexGard Spectra's broader intestinal worm coverage tips the balance in its favor.

Puppy Use

Both products can be started in puppies from 8 weeks of age. The difference is the minimum weight: NexGard Spectra requires a minimum of 3.5 lbs, while Simparica Trio can be used from 2.8 lbs. For very small or toy-breed puppies between 2.8 and 3.5 lbs, Simparica Trio is the only one of the two suitable at that weight.

Which Is Better for Active or Outdoor Dogs?

Both products are equally suited to outdoor dogs since they work systemically and are unaffected by bathing or swimming. However, Simparica Trio's faster tick kill makes it slightly more suitable for dogs with heavy tick exposure, such as those that regularly run through tall grass or wooded areas where rapid tick kill provides extra peace of mind.

The Bottom Line

For dogs with whipworm exposure risk: choose NexGard Spectra.

For adult dogs with heavy tick exposure where speed of kill matters, or toy-breed puppies between 2.8 and 3.5 lbs: choose Simparica Trio.

For most healthy adult dogs with standard parasite exposure: either product provides excellent all-in-one protection, and the choice often comes down to personal preference or price.

Both are available from Smartway Pet Supplies without a prescription, shipped directly from Australia to the USA and Canada.

Shop Simparica Trio by Weight

• Puppies 2.8–5.5 lbs (Yellow)
• Extra Small 5.6–11 lbs (Purple)
• Small 11.1–22 lbs (Orange)
• Medium 22.1–44 lbs (Blue)
• Large 44.3–88 lbs (Green)
• Extra Large 88.1–132 lbs (Red)

Shop all Simparica Trio → | Shop NexGard Spectra →