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Best Flea Medications

By: Carl Laron on April 24, 2018

Oral treatments kill adult fleas only

For pet owners who find topical flea treatments messy or inconvenient, medications in tablet form can be a simpler solution. Capstar for Dogs and Cats (Est. $25 for six doses) is an over-the-counter medication that works on pets between two and 25 pounds in weight. Capstar for Dogs (Est. $30 for six doses) is the same product but in a higher dosage and is intended for dogs over 25 pounds.

The active ingredient in Capstar, nitenpyram, works very quickly, killing adult fleas in as little as 30 minutes. This means Capstar can provide quick relief for pets with flea allergies. What it can't do, however, is kill flea eggs and larvae. But Capstar can safely be given as often as once per day, so pet owners have the option of repeating the dose if their pets are re-infested. Another option is to use Capstar in conjunction with a topical treatment, such as Advantage II for Dogs (Est. $45 for a four-month supply) or Frontline Plus for Dogs (Est. $35 and up for a three month supply) that does include an IGR (insect growth inhibitor) to get rid of fleas and larvae. That's the approach Nancy Kearns, editor of The Whole Dog Journal, used to get a sudden flea outbreak among her own dogs under control.

Since Capstar is a pill, it poses virtually no risk to humans who use it on their pets. Side effects in pets, while not unknown, are relatively rare. In more than 5,000 owner-written reviews across sites such as Amazon and 1800PetMeds, we found only a handful that mention any serious reactions. Some owners do complain that the product didn't work for their animal or that its effects only lasted a couple of days. Another problem some users have is getting their pets to take the pill. According to reviews, dogs will usually take the pill if it's tucked into a treat like peanut butter or cheese, but cats may be more reluctant to swallow it. However, most say that Capstar is very effective; many say they were "shocked" to see how quickly the fleas fell off their pets.

As is the case with Frontline Plus, covered in our discussion of the best topical treatments, generic versions of Capstar, with the same active ingredient, nitenpyram, are now available. Products made by larger makers, such as Sentry Capguard (Est. $25 for six doses) get okay user feedback, though there's less of it than for Capstar, and ratings are a bit lower. Reviews.com, on the other hand, gives it their recommendation over Capstar based on its lower price. However, as was the case with generic Frontline Plus, we'd recommend against opting for very-low -priced generics and generics from less familiar sources. As always, speaking to your vet about a particular product you are considering is a good idea.

We also saw many positive reviews for an oral medication called Comfortis (Est. $90 and up for six doses). Like Capstar, Comfortis works only on adult fleas, but its effects last a full month, so vets say it will continue to kill new fleas as they develop. Unlike Capstar, Comfortis is available only with a prescription from a vet, and it can only be given to pets at least 14 weeks old.

Veterinarians tend to be enthusiastic about this treatment. The vets at Mercy Animal Hospital call it very effective, and especially popular in area with severe flea problems. Dr. Jon Plant, says that its rapid action makes it a good choice for "infested pets," especially those with flea allergies. Owners generally find Comfortis very effective as well, with many saying it worked on their pets after other products had failed. At 1800PetMeds it earns a 4.5-star rating following nearly 1,200 reviews.

However, Comfortis is also much more likely to cause negative side effects than Capstar. Vomiting is the most common problem, Dr. Plant notes. The reviews we consulted from users included rare reports of more serious side effects as well. Dogs are more likely to develop those side effects than cats, and the vets at the Mar Vista Animal Medical Center note that it "May promote seizures in dogs already predisposed to seizures." Comfortis must be administered exactly as directed, and it can also interact badly with certain other medications, including ivermectin, which is used in most treatments for heartworm. The manufacturer advises pet owners to use this product only under the guidance and supervision of a veterinarian.

Most pet owners find Comfortis easy to use. Users like the fact that, unlike topical treatments, it doesn't have any odor or leave a greasy residue on the pet's fur. However, a few pet owners say getting the pet to take the pill can be tricky, and Dr. Plant lists one of the major drawbacks as being "the relatively low palatability of the chew tabs." Some users say their pets ate the beef-flavored tablet right out of their (the owners') hands, but others say they had to resort to tricks like slipping it in a "pill pocket" or grinding it up and mixing it with peanut butter.

If getting your dog -- and only your dog, as it's not suitable for cats -- to take their flea medication is a challenge, NexGard (Est. $60 for three doses) could be the solution. These chewable tablets, available by prescription only, are beef flavored and eagerly gobbled up by dogs -- "NexGard is tasty and goes down easily most of the time," Dr. Plant says. It's relatively new, but is already garnering good feedback from users as well, including a 4.5 star rating at 1800PetMeds based on nearly 500 reviews. Side effects are not unheard of but seem to be relatively rare. Vets so far are reporting good results as well. Dr. Thomas B. McMillen at the Mercy Animal Hospital in Cranston, R.I., calls it "Probably our favorite at the current time."

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