Is it Safe to Apply K9 Advantix Twice in One Month?

My dog [English Springer] has fleas and he has been on flea/tick meds. for 6 years. On the 1st of the month I applied his...

Dr. Eric Barchas  |  Aug 19th 2010

My dog [English Springer] has fleas and he has been on flea/tick meds. for 6 years. On the 1st of the month I applied his Advantix but he’s been itching like crazy and today I found a flea on him. I ran to Walmart and gave him a flea dip bath by Hartz and almost cried after reading your review on using Hartz. I wanted to know if I can apply another tube of Advantix, is it harmful to apply it twice in a month?

Do you think that I need to have him dipped/bathed at the vet in order to really fight off the fleas? I am exhausted after cleaning the house and washing every blanket and rug in sight. I’m sure other pet owners have wondered about reapplying the nasty, messy flea/tick treatment.

Thanks for your time and help.

Parkland, Florida

K9 Advantix should not be applied more than once in a month. More on that in a moment. But first, a little history (as I see it, based solely upon personal experience).

Long (that is to say, 20 years) ago there was no good flea preventative. Pet owners had two choices: use primitive pesticides that had low safety margins (and that can still be found in Hartz, Sargeant’s, BioSpot, flea dips, and flea bombs), or live with fleas. Then came Advantage and Frontline.

Advantage and Frontline changed everything. They were completely new products that were phenomenally toxic to fleas (that’s good). They were phenomenally non-toxic to mammals (that’s also good). They worked and they were safe.

However, Bayer (the manufacturer of Advantage) had a problem. Frontline prevented tick infestations. Advantage did not. Bayer’s solution was K9 Advantix–it also prevents tick infestations.

The “K9” should tip you off. Unlike regular Advantage, K9 Advantix is not safe for and must not be used on cats. That’s because K9 Advantix is simply Advantage with permethrin added. Permethrin is an old school pesticide with a safety margin that is, in my opinion, substandard. I do not recommend applying it twice in one month. If you are concerned about ticks, I feel that Frontline is a more elegant product.

I will say one thing for K9 Advantix: it is effective. If you have been applying it properly and your dog is infested with fleas then something is out of whack. There are reports of counterfeit, ineffective products available at pet stores and on the internet. If you did not purchase your product from a reliable source it might not be effective. Resistance to K9 Advantix has not yet been verified and is not likely. Improper use of the product is the number one cause of failure.

Flea bombs and flea dips are less effective than high quality flea preventatives. They also don’t kill flea pupae (nothing kills flea pupae–they easily could survive a nuclear blast). Don’t waste your time with them. I recommend instead that you use a second, high quality flea product that is compatible with Advantage (and K9 Advantix). Comfortis and Capstar are oral products–if you use one of them you won’t have to deal with an additional messy spot on your dog. Talk to your vet about this.

Finally, be aware that if fleas or especially flea pupae are present in the environment you may occasionally see a flea on your pet even if you are using an effective product. No flea product kills the pests instantly, so dying fleas may be noted rarely on pets who are not in fact infested.

Photo: no match for a flea pupa.