Choosing between NexGard and Simparica Trio is one of the most common dilemmas dog owners face when shopping for all-in-one flea, tick, and heartworm protection. Both are chewable, vet-grade tablets that dogs actually enjoy taking — but they differ in spectrum of coverage, active ingredients, and value for money. Let's break down exactly what each product offers so you can pick the right fit for your dog.
What Each Product Actually Covers
This is where the biggest difference lies. NexGard is a monthly chewable that targets fleas and ticks. It does an excellent job at both, killing fleas within eight hours and multiple tick species within 48 hours. However, it does not cover heartworm or intestinal worms on its own.
Simparica Trio, on the other hand, is a true all-in-one solution for flea, tick, and heartworm prevention — plus it also treats and controls roundworms and hookworms. If you want a single monthly chewable that handles parasites inside and out, Simparica Trio covers more ground in one tablet.
For dog owners who want comprehensive parasite defense without juggling multiple products, that broader spectrum matters. Browse our full flea, tick, and worm category to compare all available options side by side.
Active Ingredients Compared
NexGard uses a single active ingredient: afoxolaner. This belongs to the isoxazoline class, which disrupts the nervous system of fleas and ticks, killing them quickly after they bite.
Simparica Trio combines three active ingredients: sarolaner (also an isoxazoline for fleas and ticks), moxidectin (for heartworm prevention), and pyrantel (for roundworms and hookworms). The triple-action formula is why it can deliver all-in-one flea, tick, and heartworm coverage in a single chew.
Both isoxazolines — afoxolaner and sarolaner — work through a similar mechanism, so flea and tick efficacy between the two products is comparable. The real differentiator is Simparica Trio's added worm protection.
Quick tip: If you're currently giving your dog a separate heartworm preventive alongside NexGard, switching to Simparica Trio could simplify your routine to just one chew per month — and potentially save you money.
Effectiveness and Duration
Both NexGard and Simparica Trio are dosed once every 30 days, making them equally convenient from a scheduling standpoint. They're both flavored chewables, and most dogs take them willingly as a treat.
NexGard begins killing fleas within eight hours and achieves close to 100% flea kill within 24 hours. It also starts eliminating ticks within 48 hours of administration and maintains protection for the full month.
Simparica Trio starts killing fleas within four hours — slightly faster initial knockdown — and reaches full efficacy within eight hours. Tick kill begins within eight hours as well. Its heartworm prevention works continuously throughout the monthly dosing period when given consistently.
Both products maintain strong efficacy right through to the next dose, provided you stick to the monthly schedule without gaps.
Safety and Side Effects
NexGard is approved for puppies eight weeks of age and older, weighing at least 1.8 kg. Simparica Trio is approved for puppies eight weeks and older, weighing at least 1.25 kg. Both have been through extensive safety testing and are well-tolerated by the vast majority of dogs.
Reported side effects for both products are uncommon and typically mild. They may include vomiting, diarrhea, lethargy, or decreased appetite. As with all isoxazoline-class products, caution is advised for dogs with a history of seizures.
Neither product is suitable for cats. Always match the correct weight range to your dog when purchasing to ensure safe and effective dosing.
Which Offers Better Value?
On a per-tablet basis, NexGard is typically the more affordable option. But that comparison can be misleading because NexGard only covers fleas and ticks. If you need heartworm and intestinal worm protection too, you'll be buying a second (or third) product, which adds up quickly.
When you factor in the cost of separate heartworm and worming treatments alongside NexGard, Simparica Trio often works out cheaper overall. One purchase, one chew, full coverage — it's hard to beat that convenience.
That said, if your dog is already on a heartworm plan you're happy with and you only need flea and tick control, NexGard remains an excellent standalone choice at a lower price point.
Here's a quick summary to help you decide:
- Choose NexGard if you only need flea and tick protection, or if you already have a separate heartworm and worming routine you prefer.
- Choose Simparica Trio if you want a single chewable that handles fleas, ticks, heartworm, roundworms, and hookworms — simplifying your dog's parasite prevention into one monthly dose.
Frequently Asked Questions
Can I switch my dog from NexGard to Simparica Trio?
Yes. Simply give the first Simparica Trio tablet on the date your next NexGard dose would have been due. There's no washout period needed between the two products, so the transition is straightforward.
Does NexGard protect against heartworm?
No. NexGard only covers fleas and ticks. If your dog needs heartworm prevention, you'll need to add a separate product or consider switching to an all-in-one option like Simparica Trio that includes heartworm coverage.
Are these chewables safe for puppies?
Both products are approved for puppies from eight weeks of age, provided they meet the minimum weight requirement. NexGard requires a minimum weight of 1.8 kg, while Simparica Trio's threshold is 1.25 kg. Always select the pack that matches your puppy's current weight.
Finding the right parasite protection doesn't have to be complicated or expensive. Explore our full range of flea, tick, and worm treatments for dogs to grab the best price on whichever product suits your pet — and have a quick chat with your vet if you're unsure which option fits your dog's individual health needs.