Quick Verdict
NexGard wins on raw efficacy — 99.9% flea kill in 4 hours vs Frontline's 95% in 12 hours. Frontline wins on cost and accessibility — no prescription needed, available anywhere, and no neurological advisory. The choice depends on whether your dog has a seizure history and how much protection speed matters.
Quick Answers
- NexGard: oral chewable, 99.9% flea kill in 4 hours, prescription required
- Frontline: topical spot-on, 95% flea kill in 12 hours, no prescription needed
- NexGard wins: efficacy speed, can't wash off
- Frontline wins: cost ($45-60 vs $70-85 per 6 months), OTC availability
- Seizure history dogs: choose Frontline — NexGard carries isoxazoline advisory
In This Article
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Different products solving the same problem differently
NexGard and Frontline Plus use completely different delivery systems, which is why comparing them by active ingredient alone misses the point.
NexGard (afoxolaner): Oral systemic. Your dog chews the tablet, afoxolaner absorbs into the bloodstream. Fleas and ticks die when they bite and ingest it. Nothing to wash off. Starts working in 4 hours.
Frontline Plus (fipronil + S-methoprene): Topical. Applied to the skin, distributes through the coat via sebaceous glands. Kills on contact. Can partially wash off with repeated bathing. Starts working in 12-24 hours.
That difference in mechanism explains most of what follows.
Efficacy
Clinical data side by side:
- NexGard flea kill: 99.9% within 24 hours, starts at 4 hours
- Frontline Plus flea kill: 95-98% within 24 hours, starts at 12 hours
- NexGard tick kill: 93.3-100% within 48 hours depending on species
- Frontline Plus tick kill: 90-95% within 48 hours depending on species
NexGard is faster and marginally more effective. The 4-hour vs 12-hour start time makes a real difference during heavy flea exposure. For tick prevention specifically, NexGard's efficacy on deer ticks — the Lyme disease carrier — is stronger.
Safety
NexGard is an isoxazoline. The FDA's 2018 advisory documents muscle tremors, ataxia, and seizures in some dogs — primarily those with pre-existing neurological conditions. Low rate in healthy dogs, but documented.
Frontline Plus uses fipronil, which has been on the market since 1996. Thirty years of safety data, no neurological advisory. For dogs with a seizure history or owners who want to avoid systemic drugs, Frontline is the clearer choice.
Cost
At Canada Pet Care per 6-month supply:
- NexGard: $70-85 ($12-14/month)
- Frontline Plus: $45-60 ($8-10/month)
Frontline costs $30-40 less per 6 months. For multi-dog households the gap compounds fast.
Purchasing
Frontline Plus is OTC — no prescription anywhere in the US. Pick it up at Petco, Chewy, Amazon. NexGard requires a US prescription. Through Canada Pet Care you can order without one via parallel importing, but you're looking at 7-10 day shipping.
Once you have both products, the convenience flips. NexGard is a beef-flavored chew most dogs eat without drama. Frontline requires parting the coat, applying to skin while the dog stays still, and keeping the site dry. Monthly Frontline on a squirmy dog is a real inconvenience that NexGard eliminates.
Water exposure
NexGard — systemic, completely waterproof. Swim immediately after dosing, zero impact on efficacy.
Frontline Plus — manufacturer says waterproof after 24 hours. Dogs that swim often or get bathed monthly tend to show reduced Frontline efficacy toward the end of the 30-day period. Not an issue for most dogs, but relevant if yours swims regularly.
Who should choose NexGard
Healthy dogs without seizure history. Dogs that swim or get bathed often. Dogs that won't tolerate topical application. High-flea environments where fast kill time matters.
Who should choose Frontline Plus
Dogs with seizure history or neurological conditions. Multi-dog households where the $30-40 saving per 6 months adds up. Owners who want OTC convenience without prescriptions or international shipping. Dogs where minimising systemic drug load matters for other health reasons.
Frequently asked questions
Can I switch between NexGard and Frontline?
Yes. Switch at the start of any monthly cycle with no washout period. If switching from NexGard to Frontline, wait until the current NexGard 30-day window completes first.
Is Frontline Plus still working in 2025?
Flea resistance to fipronil has been documented in some areas — parts of Europe and isolated US regions. If you use Frontline and notice reduced effectiveness, switching to an isoxazoline like NexGard typically resolves it. No documented NexGard resistance exists.
Does Frontline Plus prevent heartworm?
No. Frontline covers only fleas and ticks. Heartworm requires a separate product or a combination tablet like Simparica Trio.
Buy NexGard at Canada Pet Care →Pros & Cons
Pros
- Clear head-to-head comparison — genuine help for decision-making
- Covers the prescription vs OTC trade-off honestly
- Addresses the seizure safety question directly
Cons
- NexGard requires prescription in US (available at Canada Pet Care without Rx)
- Frontline resistance documented in some regions
Comparison Table
| Product | Type | Flea kill start | Flea efficacy | Waterproof | Rx required | Price/6mo |
|---|---|---|---|---|---|---|
| NexGard | Oral chewable | 4 hours | 99.9% | Yes | Yes (or Canada Pet Care) | $70-85 |
| Frontline Plus | Topical spot-on | 12 hours | 95-98% | After 24h | No | $45-60 |
| Bravecto | Oral chewable | 2 hours | 98.7% | Yes | Yes (or Canada Pet Care) | $55-65 |
| Seresto Collar | Collar | 24 hours | 95% | Yes | No | $50-65 |
Bottom Line
For healthy dogs in high-flea environments, NexGard's faster and more reliable kill rate is worth the prescription hassle and cost premium. For dogs with seizure history or owners wanting over-the-counter convenience, Frontline Plus is a solid and proven alternative.