Frontline vs. K9 Advantix: What’s Best for Your Dog?

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Flickr (Pingz Man)

As temperatures rise, so does the urge to get outdoors and start adventuring. This means trips to the lake, the ocean, the woods, and even to wide-open fields. There will be cookouts, hikes, and picnics. The more time spent outdoors, the better. Until the bugs arrive.

Not only do us humans have to worry about mosquitos and ticks but so do our furry friends as well. If you have a dog and you want to take them with you on any of your outdoor activities, it’s absolutely essential that you treat them with some form of flea and tick prevention. Not only do bug bites jeopardize your dog’s health but they are becoming a more prevalent issue with each coming year.

According to this article from the Guardian, tick populations are on the rise. Science Magazine also points out that ticks that carry Lyme disease are now in half of all counties in the U.S. It’s a pretty serious problem due to get worse. Writers at Science X posit that even flea populations are rising due to climate change.

By far the most popular solution for prevention is a topical liquid that lasts about a month. The question is: which one?

The two heavyweights in the topical flea and tick prevention category are Bayer’s K9 Advantix II and Merial’s Frontline Plus. They’re the most recognized names in the business, and the ones most trusted by vets. We recommend that you discuss any treatment options with your vet before you make your decision, but it can be helpful to have a few points of comparison when shopping. Let’s tackle some of the key differentiators that set these two products apart.

1. Frontline vs. K9 Advantix: Adverse Reactions

Image of frontline package


With either product, the occurrence of side effects is very low. The most common side effect is very temporary irritation at the treatment site. This generally clears up quickly and leaves no permanent marks. Bayer says that in a very small percentage of dogs, burning, tingling, itching, redness or numbness of the skin can begin one to two hours after treatment when using Advantix.

Additionally, Advantix could be a concern for multi-pet households. Advantix contains permethrin, which is totally fine for dogs, but lethal to cats. Cats should never be given Advantix directly (instead, you’d want Bayer Advantage), and can also pose a problem if your freshly-treated dog plays or cuddles with the cat.

Some online sources report that vets have seen cases where someone has inadvertently treated their cat with Advantix instead of Frontline when they had both on hand. If you have a cat, you’ll probably want to avoid Advantix altogether.

Advantage: Frontline.

2. Frontline vs. K9 Advantix: Reviews

Image of advantix package


On the whole online reviews of these two products are relatively comparable. Because they have the same application style, neither brand gets an advantage for ease of use. Both products solid performers that most owners find work perfectly well, particularly in urban environments.

While the active ingredient permethrin in Advantix is more often praised for its ability to kill pests, rare skin irritation does render negative reviews.

On the whole, though, Frontline generally earns lower scores on internet reviews. The product appears to have more variance from batch to batch, with longtime users claiming it suddenly stopped working. Some of this is due to people’s opinions on the efficacy of fipronil, the active ingredient in Frontline. An increasing trend of users claim that it loses its effectiveness over a period of time. This is highly variable to the dog, though, so you should try it with your animal and discuss with your vet if you suspect that it isn’t working.

Advantage: Advantix.

3. Frontline vs. K9 Advantix: Effectiveness

Image of advantix package


While the efficacy of both products will depend on their proper use, various resources suggest a few trends when comparing these products.

First, Advantix has a broader scope of what it kills and repels. Advantix kills and repels fleas, ticks, and mosquitoes, kills lice, and repels biting flies. By comparison, Frontline kills but does not repel fleas, ticks, and lice, but has no effect on mosquitoes nor biting flies.

On the other hand, one major advantage of Frontline is that it will work on flea eggs, not just hatched fleas. This is somewhat mitigated by the fact that Advantix repels them in the first place. In this case, Frontline might be better if you already have a flea infestation, whereas Advantix is the choice to repel everything before an infestation or bite occurs.

Second, there is some debate over whether or not Frontline resistance is a growing problem. It hasn’t been well-studied or documented, but reports of dogs being attacked by ticks even when treated with Frontline aren’t hard to find given a cursory look around the internet. Still, lacking concrete evidence, it’s hard to say if improper application might have something to do with a perceived drop off in flea and tick prevention. Conversely, Bayer has tested Advantix for resistance and found none. Ask your vet to go over the data with you, if this is a concern.

Some buyers don’t trust Frontline’s active ingredient of fipronil, but for every account that it doesn’t work, I’ve seen several that swear by it. My advice is to not read too much into the hype about a given chemical without trying it. Obviously, in the case of Advantix, if you have cats, it will certainly be much less useful to you since it could possibly endanger the health of your other pets.

Some vets believe that Advantix works slightly quicker, but that by the end of the 30-day window, the performance is roughly the same. Bayer’s claim is that Advantix works within 12 hours, while Frontline claims to work within 18, so this impression is probably correct.

Advantage: Anecdotal evidence suggests a slight edge for Advantix.

4. Frontline vs. K9 Advantix: Price

Image of advantix package


This is a difficult topic to grade these products on, as the prices of these two flea treatments are highly variable depending on deal pricing, dog size, pack size, and where you decide to buy. There are too many factors at play for one product to have a clear edge, but the packaging of these products is slightly different and that can make a difference depending on how tight your monthly budget is.

Both Frontline and Advantix are meant to be used once a month, and both are sold in multi-packs. The only crossover point in package size for the two brands is that they both come in six dose packages. Advantix also comes in one, two, and four dose packs, while Frontline is available in three or eight month packs.

There are also slight differences in what weights each product serves. Frontline’s weight distinctions are: five to 22 pounds, 23 to 44 pounds, 45 to 88 pounds, and 89 to 132 pounds.

Advantix has options for four to 10 pounds, 11 to 20 pounds, 21 to 55 pounds, and over 55 pounds.

Overall, this shouldn’t make much of a difference, but if your dog is on the cusp of a weight class, this might push you into a different consideration. Whatever option you choose, we do recommend the six dose boxes because being covered for half the year with one purchase is both convenient and cost effective relative to restocking more frequently. Still, if the overall package price is your primary concern, the three-packs are probably the sweet spot.

If you’re buying on Amazon, you should know that the Frontline product listings are not as organized as those of Advantix; you’ll sometimes have to hunt around for the dog and package size combination you want, whereas Advantix lists all package sizes on each dog size page for easy buying.

Advantage: Tie, thanks to similar-enough pricing and regular price fluctuations

5. Frontline vs. K9 Advantix: Conclusion

Image of frontline and advantix packages

Based on the factors we’ve compiled here, Advantix is likely the product to choose for your dog — as long as you don’t have cats. Generally speaking, Advantix is considered faster-acting, kills and repels a wider variety of pests (including mosquitos), is comparably priced to alternatives, and has less of a reputation for fading efficacy over the years. Bayer also makes one of the highest-rated dog dewormer medications too.

Because Advantix is available in one-dose package sizes, it’s a bit easier to try for one month to see the results. With Frontline, you’ll have to buy three doses and if you find it doesn’t work, you may end up wasting one.

By contrast, Frontline is safe for use in households with cats and the option to buy in three packs may appeal to some. Both products have been in successful use for years, so either is a reliable option to consider.

Can You Combine Flea Treatments?

While you should absolutely not use two once-a-month, topical treatments at the same time, it could be a good idea to combine two different types of products. For example, it’s become increasingly popular to adopt a multi-layered approach that combines the use of a topical agent with a repellent collar. The combination may help shore up weaknesses in any given product.

You should wash your dog regularly with flea shampoo, as well, as this physically removes fleas and flea dirt, which will improve the effectiveness of other solutions. Be sure to let your topical dose absorb for the recommended amount of time before bathing your dog, but giving them a bath just before a dose is a good idea.

It’s also important to treat you home as you treat your dog. With these products, your dog helps to upset the cycle of flea reproduction, but if you don’t treat your home, you’re likely to see far less success. In addition to using multiple products on your dog, consider something like a flea spray for your home, as well, to improve your chances.

Be sure to discuss treatment options with your vet before applying any of these products to your pet. It may take some experimentation to find the best flea and tick prevention treatment for your dog in your area of the country. Given the growing threat of fleas and ticks, these products are virtually mandatory for the modern pet owner.

Buy Bayer K9 Advantix II Flea and Tick Control Treatment for Dogs here.

Buy Merial Frontline Plus Flea and Tick Control here.

Heavy, Inc. is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by linking to Amazon. Our product recommendations are guided solely by our editors. We have no relationship with manufacturers.
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