Anti-Flea Medications

Internal anti-flea medications

While only a small minority of veterinarians and pet experts believe topical anti-flea medications can have potentially deleterious effects on pets, there is a good alternative for the wary pet owner: internal medications, which are administered in pill or suspension form. These medications cause the animal's skin to secrete a substance that inhibits the development of flea eggs, thus interrupting this pest's life cycle. The advantage is that the pet isn't constantly exposed to topical insecticide; the disadvantage is that these medications take a few weeks to work, and flea infestations will persist until they do (and the pet may even pick up fleas between the time the pill is administered and it starts to work). Also, to the surprise of many owners (especially if they haven't been adequately briefed by their vets), anti-flea pills or suspensions have no effect on adult fleas.

On the whole, veterinarians recommend internal medications for pets that are chronically susceptible to flea infestations or that are constantly exposed to flea-infested environments. While there's no evidence that a six-month stint on Advantage or Revolution will adversely affect a pet's health, few owners would be willing to smear these topical medications on their dogs and cats for the extent of their natural life spans. We found no qualms from pet experts about keeping pets on internal anti-flea medications for years at a time, though of course no one can be absolutely sure about long-term side effects.

As with topical medications, we found that the majority of veterinarians and pet experts recommend different internal medications for dogs and cats. For cats, there are many positive reviews of Program Once-a-Month Oral Suspension (*Est. $45 for six-pack) . (Program is also available in pill form, which is slightly less expensive, but harder to administer to felines.) One advantage of Program is that it's not technically a prescription product, though it's still sold primarily through veterinarians -- and it's always a good idea to get the opinion of a vet where fleas are concerned. You can also ask your vet to administer Program to your cat in a single injection good for six months.

Although Program is also available for dogs, many of the sources we found recommend Sentinel Flavor Tabs (*Est. $60 to $85 for six-pack) (*est. $60 to $85 for six-pack, depending on the dog's weight). Sentinel contains the same active flea-control ingredient as Program, combined with a chemical that controls heartworm, hookworm, roundworm and whipworm. Like Program, Sentinel can be used safely in conjunction with most other anti-flea measures, including collars, shampoos, dips and even some topical treatments (for killing adult fleas).

We found one other pill-based flea medication that's recommended by some veterinarians. Capstar (*Est. $25 for six tablets) is a pill that starts killing fleas on your pet within half an hour, and continues to work for 24 hours. However, unlike the topical and internal medications discussed above, Capstar is not a long-term flea control solution, since it doesn't interrupt the flea life cycle (by killing eggs) or prevent re-infestation after its effects have worn off. Still, many experts and owners say Capstar is a good, short-term solution to an acute flea crisis. Like Program, Capstar is not a prescription product, so you don't need a vet's prescription to try it.