Frontline Plus Review: Treatment, Effectiveness, And Side Effects

Frontline plus

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Frontline plus

For pet owners, one of the most important factors in maintaining your animal’s health is flea and tick prevention. The diseases that fleas and ticks carry are not just a concern for dogs and cats, but several of the ailments can inflict considerable harm on humans too. So stopping these little pests is not only vital to the health of your pet but in many cases the health of your entire family.

So what is the best way to deal with the nuisance of these disease carriers? Thankfully there’s plenty of options available on the market that include chewable, pill, and topical applications. One such product is the Frontline Plus line of flea and tick medications. Let’s take a look at this popular brand of flea and tick treatment and see if it’s right for your pet.

Frontline plus

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What Is Frontline Plus?

Frontline Plus is a monthly topical application that is made by Merial, an animal healthcaresubsidiary of German company Boehringer Ingelheim. They also produce the widely used prescription-only chewable NexGuard (flea and tick treatment for dogs) and Heartgard Plus (heartworm protection).

Initially introduced in 1997, Frontline Plus has seen a considerable rise in use over the past two-plus decades. It’s understandable considering the rapid increase of vector-borne diseases during a similar time frame.

The active ingredients in the topical treatment include fipronil and S-methoprene. Fipronil was initially developed in the late 1980s and is a general use insecticide that is meant to kill fully grown adult fleas and ticks.

The S-methoprene is a chemical compound that has been around in general use since the late 1970’s. Its primary function is to eliminate flea eggs and larvae, effectively destroying the lifecycle of the microscopic pests.

What Does It Protect Against?

As noted above, Frontline Plus is made to kill fleas and ticks and eradicate any eggs or larvae that may be left behind. Aside from the nuisance and discomfort these pests can cause, they are also carriers of several diseases that can infect not only your dog but you and your family members as well.

woman holding a dog and cat

Fleas can transmit several diseases including murine and rural epidemic typhus and plague. Though not as commonly occurring in developed countries, the risk of contraction is typically seen in adults, but can be high among children or the elderly whose immune systems are still developing or weakened, respectively.

Ticks, for their part, are particularly nasty. They can carry a number of diseases with the most well known of these being Lyme disease, and Rocky Mountain spotted fever. While unpleasant to contract, both are rarely fatal if treated promptly.

Both fleas and ticks are prevalent throughout the US. Every state in the country has an active flea season, with approximately 15 states in the west, south, and southeast seeing them year round. Another 15 experience them from February to December. For an idea of just how rampant fleas can be, they can lay eggs and reproduce in just under three weeks.

The pervasiveness of ticks follows a similar pattern although the spread of Lyme disease tends to be more concentrated in the upper Midwest and northeast. This further highlights that both fleas and ticks are a common concern throughout the nation.

Who Does It Protect?

The obvious answer is man’s best friend, of course (as we’ll note later it protects cats, too).  But as we mentioned earlier, the need for flea and tick treatments goes far beyond the comfort and health of your dog. By stopping the spread of fleas and ticks in your pet, it also helps to minimize their transmission to humans.

In the course of our review, it was apparent that the Frontline Plus does its job at its initial point of contact, on the dog itself. This does not mean, however, that it eliminates the presence of fleas and ticks elsewhere in and around your home (thus the importance of keeping your dog on a regular treatment schedule).

To ensure you get the most from the treatment, we do recommend you take additional preventative measures. Treating your yard should be first and foremost by keeping your grass cut and brush piles to a minimum.

Also, any areas where your dog may congregate in your house should also receive regular attention. Bedding, carpet, and furniture potentially could harbor the parasites, especially in climates conducive to the spread of fleas and ticks.

How Does It Protect Your Pet?

Applied once every 30 days, Frontline Plus kills fleas and ticks on contact (not through biting) by populating a dog’s glands with an oily medicated layer of protection. The application process is relatively easy.

Through a small applicator with the appropriate dose already measured out, you apply the medication directly on the dog’s skin between its shoulder blades on its neck (effectively placing it where the dog cannot lick).


The solution, however, can take up to 24 hours to become active as it absorbs through the animal’s glands. This is a pretty poor onset time and is one of the most significant drawbacks to the medication. It’s important to maintain that 30-day schedule otherwise a day or two of non- treatment could create havoc.

Once applied, the medication continues to self-distribute throughout the treatment period. It does appear to work as advertised for the month-long time frame. The product is waterproof, which is nice if your dog is a regular bather or does any lake or pool swimming. However, it is suggested to not get your dog wet during the initial 24 hours after application.

The dosages vary based on the size of your dog, and there are four different ranges to choose from: 5 to 22 lbs, 23 to 44 lbs, 45 to 88 lbs, and 89 to 132 lbs. There is no real age restriction as you can start applying the medication as early as eight weeks.

Side Effects

While overall considered safe by the vast majority of veterinarians, Frontline Plus does have the potential to cause side effects in your dog. In most cases, these are nominal to mild, but as with any medication, you should monitor your animal closely after application. Should any adverse condition linger for more than a few days, you should contact your vet immediately.

As Frontline Plus is a topical application, the main concerns are skin allergies or adverse reactions in the dog. Owners who’ve encountered this report seeing redness or a small rash in the area of the dosage. Another indication there may be a problem includes your dog itching more than usual, though the dead fleas rising to the top of the haircoat could also cause this.

Other potential side effects include nervous system damage, carcinogenic activity, organ damage, and infertility. While rare, it is important to remember that the active ingredient of fipronil is a neurotoxin, so the potential is there for some adverse reactions.

Just like in humans, medications will affect dogs in different ways with puppies and older hounds more susceptible to harmful effects than healthy canines in their prime years.

With that said, it is essential to understand how your pet reacts to certain medications and monitor them throughout the application cycle. Frontline Plus is no different.

In our research, the vast majority of dog owners reported no problems and was very happy with the results. Regardless, always keep a close eye on your pet and report any potential concerns to your vet as soon as possible.


Overall, Frontline Plus works as advertised. The vast majority of users report absolutely no development of parasites on their dog or in and around areas where it would spend most of its time. A lot of first-time users noted dead fleas at the top of their dog’s coat, which is normal and an indication the product is working.

Conversely, some users did find the medication ineffective for their particular pet. While not altogether typical, as we stated, pet medications, just like those for humans, may not work for everyone. In cases like these, we recommend touching base with your veterinarian to find something that is effective for your pet.

A small minority noted that some irritation occurred in the application area, but most indicated it disappeared within a day or two and did not return upon later doses.

What About Cats?

As most dog lovers would say, “what about them?” All dog versus cat joking, aside if you happen to be the owner of both a dog and a cat, you should never use the canine version of Frontline Plus on your cat. There is a specific Frontline Plus formula that can be purchased for your feline friend as well.

How Does It Rate Against Other Treatments

As a dog owner, it indeed can be confusing of what to use with all of the options available to treat fleas and ticks. As we’ve shown, even with a couple of minor issues, Frontline Plus is an effective treatment for you to consider. But how does it compare with other prevention methods on the market? Let’s take a look at four other top products:

vs. Advantix II – Topical

Made by Bayer Animal Health, Advantix II is one of the most popular flea and tick treatments available today. Not only does it address the two main parasites, but it has the claim of also taking care of mosquitos. In the same way that Frontline does, a biting action is not necessary as contact is enough to kill any pest.

Though it’s hard to determine how well the mosquito protection works, the Advantix II is fast acting with an onset of fewer than 12 hours. Every other aspect is on par with Frontline Plus including 30-day treatment cycle and waterproof formula.

vs. Advantage II – Topical

Advantage II is a sister product to Advantix II, made by the same manufacturer. Similarly effective against fleas, Advantage II does not have an active ingredient to fight tick infestation, which severely limits its scope.

Like Frontline Plus, its waterproof with a duration that lasts 30 days but it does have a faster onset time of fewer than 12 hours versus 24. Frontline Plus gets the nod here as it treats both fleas and ticks.

vs. Capstar – Tablet

If you’re looking for a non-topical option, Novartis’ Capstar Flea treatment offers a tablet formula for fleas. Unfortunately, that’s all they offer. Also, the tablet only addresses fleas that are present on or within your dog, so its scope is incredibly narrow with the chance of re-infestation very high.

It is however fast acting with onset under four hours. It doesn’t match up with Frontline Plus, but is useful for an immediate solution before a more permanent treatment is found.

vs. Vet’s Best Flea and Tick Home Spray – Spray

The name says it all. Vet’s Best is a spray that serves as a good option for pet owners looking for something a bit more natural and versatile. From a blend of natural ingredients, this spray is not only used directly on your dog, but you can spray it onto carpets, pet beds, rugs and anywhere else fleas and ticks may camp out.

Frontline Plus does serve as a more permanent and direct solution for your dog, but Vet’s Best Spray is a good backup for spot treatments wherever you may find a flea or tick.

Final Recommendation

It’s hard to argue against over 20 years of satisfied pet owners and healthy, flea and tick free dogs. There are plenty of advantages to using Frontline Plus, most of all its simple application, 30-day effectiveness, and its waterproof formula. Yes, some drawbacks exist, but those are far outweighed by the positives.

While the medication is available for over the counter purchase, we do strongly recommend speaking with your vet first to determine if is right for your dog. Remember that the active ingredient fipronil is a potent insecticide, and though we listed some of the possible side effects above, you should still review theme with a professional.

Ultimately, Frontline Plus works and works well. It may not be for everyone, but to ensure that your dog is kept happy, healthy and flea and tick free, we certainly recommend giving it a try.

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