Nexgard vs. Simparica : Comparison and Key Differences

There are many chewable options but how do you know which one is the right one for you. There used to be only a small handful of options, and now you’ve got so many choices that it can be difficult to know where to start.

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Chewables are excellent alternatives to flea preventatives that must be applied to the skin. Spot-on treatments are messy and complicated to keep away from children and other pets while it all absorbs into the skin. It’s also an issue for pets who love water or who need frequent baths because the effectiveness lowers with each water contact.

Chewables are a great alternative, and we’re comparing two of them here, Nexgard and Simparica, to see which one is the right one for your pet. Let’s take a look.

Which is Better Nexgard or Simparica for Dogs?

Simparica offers better protection for longer. It’s more effective at killing fleas and ticks and has a 95% effectiveness rate even at the 30-day mark when Nexgard’s effectiveness begins to drop significantly. This is especially true of tick control.

Nexgard is useful for when you can’t get Simparica, but we love the faster, more thorough effectiveness of Simparica overall. Since they both require a prescription and are both comparably priced, there’s not much reason to choose Nexgard over Simparica. The specific neurotoxin is just better overall.

One simple reason would be the age requirement. Nexgard can begin with dogs as young as eight weeks while Simparica has to start at six months. We would use Nexgard only as long as it takes for your dog to get to the appropriate age.

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Which is Better Nexgard or Simparica for Cats?

Neither treatment is suitable for cats. You can’t just administer a medication made for dogs because feline biologically is so radically different. It can be ineffective at best and dangerous at worst.

Talk to your vet about chewable options for cats that can help control flea populations without putting your cat’s health in serious risk. Since you’ve got to the vet anyway, you can discuss the best treatment option for your cat while you’re there. Don’t’ take the risk.

Key Differences Between Nexgard and Simparica

But first, the good stuff.

Our Review of Nexgard and Simparica

They both rely on neurotoxins that interrupt the breeding cycle of fleas as well as preventing feeding and causing eventual death. Both require a prescription, and neither are suitable for use in cats. After that, there are some significant differences.


Simparica is a superior preventative, but you can’t begin with it until your dog is at least six months old. That leaves a few months of non-protection. Nexgard can start at eight weeks of age, so we’d use it in place of Simparica for the period of time until six months. After that, we’d switch over after talking to our vet.


Simparica was effective even five days after Nexgard’s dosing cycle. It gives you a period of nearly a week more of effective treatment which can add up over time. Overall, you’ll be spending slightly less for your treatment because it’s good for five weeks instead of four.

Nexgard is good for a month after which coverage begins to drop sharply. Studies showed a considerable lack of effectiveness around that one-month mark, but Simparica doesn’t show significant drops until well after the dosing period. You’re less likely to go without coverage if you forget for a day or two.


This might be insignificant, but for picky dogs, it matters. The flavor of the Nexgard chewable is beef while the Simparica chewable is liver. If your dog just won’t accept the taste of one, you may have no choice but to switch to the other.

Also Read: Simparica vs. Frontline

Nexgard and Simparica Active Ingredients Comparison

Nexgard: Afoxolaner

Afoxolaner is a neurotoxin that begins to work on the nervous system of biting insects. When insects come in contact with your dog’s blood, it starts to work very quickly. The breeding cycle is interrupted, and the flea is unable to feed.

Side effects are rare, but stomach issues and diarrhea are ones that do show up from time to time. Make sure you take your pet to visit the vet if you notice a change in behavior.

Simparica: Sarolaner

Sarolaner is the same class of neurotoxin, and it works in similar ways to Nexgard. It has a faster effect and a longer period of efficacy over time. Dosing instructions are for five weeks instead of four, making it more efficient. Ticks are also affected in higher numbers than with Afoxolaner.

Again, side effects are rare, but they’re usually tied to digestive issues. Rare side effects occur if your dog has a history of seizures.

Which Treatment is the Best Priced?

Both are priced comparatively, but because Simparica gives you an extra week of coverage, that week adds up over time. The longer you’re with Simparica, the less money you’ll spend on your dog’s preventative. That extra week every dosing cycle really begins to add up.

Other than that, both are comparatively priced for a package of six, and both require a prescription. As far as that goes, the two are very comparably priced. It’s just that extra week that really adds value.

Which Do We Recommend?

We think that Simparica is more effective overall. It’s better priced and better suited to dogs. The only reason to choose Nexgard is to get over the period of time when your dog is too young for Simparica. Also, dogs with a history of seizures may find the medicine too risky. You should discuss these possibilities with your veterinarian to make the most informed decision.

We like that a five-week dosing period gives you better coverage and there’s less of a drop off period at the end of the dosing cycle. It provides better leeway. Also, it’s more effective even from the beginning for killing ticks. We think that you’ll be much happier with the effectiveness of Simparica and won’t have much reason to switch back to Nexgard.

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7 Treatment Application Tips

Giving either chewable may have some difficulties but here are few tips to get you through it.

1. If your dog doesn’t like the taste of one type of chewable, you may ask your veterinarian if you can switch to a different kind for the flavor. Simparica is only useful if your dog will actually take it. If your dog loves the taste of Nexgard, the benefits of Simparica may not be worth the constant hassle of trying to get your dog to take it.

2. If you aren’t willing to switch, you might try the sandwich method. This one plays on your dog’s excitement and anticipation of a much-loved treat. Take your dog’s favorite treat and put one in each hand. Let your dog smell the treat to know that it’s available. Give the first treat and quickly follow up with the chewable preventative. Give your dog the other treat quickly. The idea is to do it in quick succession so that your dog is so excited about the treats it loves, it doesn’t notice much that the one in the middle is different.

3. If your dog doesn’t fall for that, you might try putting the treatment into a piece of cheese or dipping it into some kind of food that your dog loves. Disguising the smell can help dogs take the treatment. A lot of your dog’s sense of taste originates in the nose, so masking the scent of the chewable tablet can go a long way.

4. Our last trick for getting your dog to eat the chewable is to fake them out. Some dogs like to hang around the kitchen while food is being prepared to jump on anything that spills. Since you know this, you could take advantage of this behavior. As you’re preparing food, drop a few things on the floor to get your pet interested. Drop the chewable somewhere in the middle of that, and your pet is unlikely to notice in the rush to get something they aren’t supposed to have. When in doubt, the fake out usually works. Be sure not to do this in a household with food aggressive pets.

5. Make sure that your dog doesn’t get any new food or drink for a few days before giving the treatment for the first time. If your dog has a reaction to the chewable, it can be hard to know if it was the chewable or if it was the new food. Instead, eliminate everything but the basics so you can be sure that it is the treatment should something happen.

6. Any dog on a chewable preventative should have access to plenty of water throughout the day. It can cause stomach irritation without plenty of water to help process the materials in the pill, so be sure you have that available beforehand. If pets seem to have some difficulty after the treatment, some fresh water can help the dog process the chewable and feel a bit more settled. If your pet appears to be drinking more water than usual, keep watch for developing issues.

7. Even if you’ve given the treatment beforehand, it’s always possible that your dog will develop an irritation. It’s best to follow the no new food rule before each dose regardless of how long your pet has been on the medication. Watch your pet’s behavior carefully for signs of change in even small things like energy levels or alertness. Dogs often are stoic about pain and discomfort, so your pet could be showing signs of difficulty subtly.

Final Thoughts

We want to reinforce that neither of these treatments is viable options for cats just yet. Some companies follow up medications with a version for felines, but until these companies do, you should speak with your vet about choosing a different route. You don’t want to put your cat in danger just to prevent fleas.

Chewables are great options for dogs who can’t’ have a spot-on treatment because of skin irritations or increased contact with children and other pets. You don’t have to worry about making a mess, and you don’t have to worry about contaminating your house with flea medication. Also, you can bathe your pet as usual, which is good news for particularly stinky pets.

Nexgard is a useful option for younger puppies because it can begin much sooner than most other chewables. It’s a good gap filler until that six-month mark when most other chewables become available. It may not be as effective, but for this period, it’s your best bet. Otherwise, hands down, Simparica is our choice.

Does your dog take chewable treats easily? Do you have any other tricks for getting a dog to take medication? Tell us all about it in the comments below.

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