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How Does Simparica Trio Work?

Are you contemplating giving your dog Simparica Trio?

Are you wondering how it works, how to use it, and what to expect from it?

Well, thankfully, you landed here today.

Having used these chewable tablets with my own dogs for numerous years, I wanted to get to the bottom and truly understand how these meds worked.

They’ve been so effective at removing and preventing fleas, ticks, heartworm, and intestinal parasites; they made me question how and why they could combat many conditions when other Simparica Trio alternatives can’t.

So let’s delve into it.

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How Does Simparica Trio Work?

Simparica Trio works by delivering a cocktail of three primary components: sarolaner, moxidectin, and pyrantel. Each plays a unique role in killing parasites, both internal and external to the body.

Sarolaner’s Role

First, we have sarolaner.

When fleas or ticks latch onto your dog’s skin to feast on their blood, they inadvertently ingest sarolaner.

This substance then disrupts their nervous system, primarily impacting the movement of charged chloride ions connected with neurotransmitters GABA and glutamate.

The end result is a chaotic nervous system, leading to paralysis and the eventual death of these troublesome parasites.

Moreover, sarolaner ensures fleas meet their demise before they can lay eggs, thus helping to keep your dog’s environment cleaner.

The Work of Moxidectin

Then there’s moxidectin, a powerful parasite exterminator active inside your dog’s body.

It takes on internal parasites like roundworms, hookworms, lungworms, and heartworm.

Similar to sarolaner, moxidectin tampers with the parasites’ nerve cells and the flow of chloride ions.

However, it does so in a unique way, causing paralysis and death of these internal parasites.

Pyrantel’s Function

Lastly, we have pyrantel, a substance primarily designed to combat roundworms and hookworms residing in your dog’s gut.

Pyrantel operates in a distinct manner from the previous two. It blocks the signals associated with the neurotransmitter acetylcholine from reaching the parasites’ muscles.

This interference causes immediate contraction, followed by paralysis and subsequent death of these harmful organisms.

How Do You Administer Simparica Trio?

Administering Simparica Trio is as straightforward as giving your dog a tablet, either with or without food, once per month.

Administering Simparica Trio is relatively simple, but here are some key pointers to ensure your pup gets the most out of this effective treatment.

  • Select the correct dosage: Simparica Trio tablets come in various strengths, depending on the size and weight of your dog. It’s crucial to select the appropriate one for your dog.
  • Delivery method: The tablets are orally administered, which means you can either place it directly into your dog’s mouth or cleverly tuck it into their food. What’s more, these tablets are flavored to make the task easier and more palatable for your dog.
  • With or without food?: While the tablet can be given with or without a meal, dogs with sensitive stomachs might benefit from having the tablet with food.
  • Consistent schedule: To maintain optimal protection against fleas, ticks, heartworm disease, and intestinal worms, ensure your dog gets a tablet every 30 days, all year round. While Simparica Trio lasts for 35 days, there’s some extra leeway to ensure your dog remains protected, should you be out by a few days.
  • Missed a dose?: Don’t worry if you’ve missed a dose. Administer it as soon as you remember, but if it’s close to the next scheduled dose, skip the missed one and carry on with the usual routine.
  • Storage: Preserve the effectiveness of the tablets by keeping them in their original packaging until use and store at room temperature.

How Long Does Simparica Trio Take To Work?

Simparica Trio takes between 4-48 hours to work, depending on the pest/parasite it is being used to kill.

Facing Off Fleas

For fleas, Simparica Trio works fast.

Within just 4 hours of your dog ingesting a tablet, fleas will begin to be killed.

By 8 hours, all fleas will be killed following this first/only dose.

Tackling Ticks

On the tick front, Simparica Trio is almost equally impressive.

It eliminates approximately 98.9% of ticks within the first 48 hours.

Not quite as rapid as with fleas, but still an amazing feat considering the stubborn nature of ticks.

Warding off Worms

When it comes to roundworms and hookworms, Simparica Trio again proves its worth.

It eradicates an impressive 99.2% of adult roundworms and at least 94% of hookworms.

Moreover, it effectively reduces the fecal egg count for roundworms, disrupting their re-infection cycle.

Learn more: How Long Does It Take Simparica Trio To Work?


Simparica Trio is the go-to medication, often recommended by vets when it comes to eradicating ticks, fleas, heartworm, and other parasites.

You can soon see why when you understand how it works.

Besides, no other medication currently on the market contains its unique formulation.

So while it may be expensive, it is incredibly effective and quick acting.

That’s why it’s my go-to medication for my dogs. Always has been. Always will.


Who makes Simparica trio?

Zoetis (a US-based pharmaceutical company) make Simparica Trio, among a host of other animal health products. Once owned by Pfizer, they now operate as an independent, standalone company.