Oral flea medications are an alternative for pet owners who are wary about putting chemical pesticides on their pet's skin. One advantage of oral medications in general is that they pose fewer risks to pregnant women, children and other pets, because there's no chance of contact with chemicals during or after application, as is possible with topical flea treatments.
Novartis has virtually cornered the market for oral flea medications with brands like Capstar, Sentinel and Program. These products either kill adult fleas or break the flea's life cycle, but not both, so you need to buy two for complete protection. In general, we didn't find as many pet-owner reviews online for oral medications as for topical flea treatments, but some products still receive plenty of feedback.
Capstar for Dogs and Cats (*Est. $30 for six doses) is the single product recommended most often by experts and pet owners alike for quickly killing adult fleas on both dogs and cats. No prescription is needed for this oral pill, which can be given as often as once a day until fleas disappear. (Most other topical and oral products can be used only once a month). The manufacturer says Capstar begins working within half an hour and will kill nearly all adult fleas within four hours. However, this product does not kill flea eggs or larvae. Capstar comes in two dosages: Capstar for Dogs and Cats works on all cats and on dogs up to 25 pounds, while Capstar for Dogs (*Est. $30 for six doses) is for dogs over 25 pounds. Capstar for Dogs and Cats is safe to use on puppies and kittens as young as 4 weeks old, as long as they weigh at least 2 pounds.
Veterinarians are generally enthusiastic about Capstar. Every veterinary site that mentions this product agrees that it kills fleas quickly and is very safe. The vets at Twin Maples Veterinary Clinic declare, "We have never seen a side effect to it. Ever." The hundreds of user reviews we found at 1800PetMeds.com, Amazon.com and Petco.com are mostly positive as well. Most owners say that Capstar works extremely fast and that they like not having to deal with the hassle and mess of trying to apply a topical treatment. Many owners say it's "amazing" how the fleas fall off. While a few users found this product ineffective, we saw almost no reports of adverse effects. Some owners do report a frenzy of scratching shortly after the pill is taken, but Novartis reports that this is a normal reaction to the fleas' biting as they die off.
Nitenpyram, the active ingredient in Capstar, is now available as a generic drug, sold on Amazon.com at $13 for 10 doses. Early reviews for this product are generally positive. Most pet owners who have tried the generic nitenpyram capsules say that they work as well as brand-name Capstar and cost significantly less. However, we found fewer than 50 reviews for this product altogether -- too few to form a solid recommendation.
The main downside of Capstar is that it works only on adult fleas. It doesn't have a residual effect -- meaning more fleas can crawl onto the cat or dog -- and it doesn't kill eggs or larvae. However, Capstar can be combined with another medication that contains an insect growth regulator (IGR), a chemical that inhibits the development of flea eggs and larvae, and thus interrupts this pest's life cycle. The most popular medication used for this purpose is Program, a nonprescription medication available as a liquid (for cats only) or a chewable tablet. Used together, pet owners say, Capstar and Program can be an effective one-two punch for knocking out a flea infestation.
Program Flavor Tabs for Dogs (*Est. $60 for a six-month supply), Program Flavor Tabs for Cats (*Est. $60 for a six-month supply) and Program Suspension for Cats (*Est. $60 for a six-month supply) contain the IGR lufenuron. Program Flavor Tabs are safe to use on animals as young as 4 weeks old; Program Suspension is approved for cats at least 6 weeks old. Both versions remain effective for one month.
The veterinarians at Main Street Pet Care consider Program Suspension the best flea-control method for cats, and the UK-based Feline Advisory Bureau recommends it as well. The 30 or so reviews we found for this product on 1800PetMeds.com are mostly enthusiastic. Reviews of the Program Flavor Tabs are more mixed, although some of the less pleased owners seem unaware that Program isn't intended to kill adult fleas. Reviewers who have used either version of Program in combination with Capstar generally say that the two products work very well together. We saw few reports of side effects for either version of Program, and none of the reactions described were severe. The most common complaint about the products is that it's hard to get pets to take them. If your cat won't swallow the medicine in either liquid or tablet form, you can ask your vet to administer Program in the form of injection that lasts for six months.
If you don't mind getting a prescription first, Sentinel Flavor Tabs (*Est. $90 for a six-month supply) are another option for killing flea eggs and larvae on dogs. Sentinel contains the same active flea control ingredient as Program, but it adds a second chemical that controls heartworm, hookworm, roundworm and whipworm. This is similar to the topical treatment Revolution, but without the tick control. Sentinel is safe to use on puppies as young as 4 weeks old, as long as they weigh at least 2 pounds. It can be purchased in either a six-month or a 12-month supply.
Main Street Pet Care recommends Sentinel Flavor Tabs above other flea control options for dogs. It stresses that while this medication is "extremely effective over the long haul," it must be given once a month, year-round, to every pet in the household. Sentinel Flavor Tabs receive hundreds of reviews at 1800PetMeds.com, with high overall ratings for both effectiveness and ease of use. However, there are a few reports of side effects, including vomiting and diarrhea.
The one oral medication we found that both kills adult fleas and prevents further infestation is Comfortis (*Est. $90 for six doses). This beef-flavored chewable tablet, used only for dogs, contains spinosad, a drug that starts killing fleas within 30 minutes and provides ongoing protection for a full month. Comfortis cannot be used for puppies less than 14 weeks old, which is the oldest age restriction of any flea treatment in this report.
Comfortis is a powerful drug with more potential side effects than Capstar, and it must be administered exactly as directed. It can also interact badly with certain other medications, including ivermectin, used in most treatments for heartworm. Most owners posting at 1800PetMeds.com report good results and no side effects. However, a notable minority do say that Comfortis caused adverse reactions, some of which were severe. Comfortis is available only by prescription, and the manufacturer stresses that this product must be used under the guidance and supervision of a veterinarian. That appears to be good advice.