What to do when pet’s flea medication stops working

 To eliminate a flea infestation, it takes patience treating your pet and your environment.

All too often, a pet owner will come in and share their experience in which he or she regularly applies topical flea prevention, yet is frustrated that after several treatments they are still seeing fleas. There are several plausible explanations for persistent flea infestations which may have nothing to do with lack of efficacy of these products.

Apply flea medication properly for maximum effectiveness

First, I ensure the pet owner is correctly applying the flea medication to his or her pet. It is important to completely part the hair and apply the product directly to the skin so that proper skin and hair follicle distribution can occur. This is something that can be somewhat of a challenge for thick haired pets; however, the pet medication will not work properly if only the hair follicles receive the medication – it must be applied to the skin. Next, it’s important to properly follow product label directions, which may vary depending on the size of your pet. For instance, for large dogs, Advantage II requires the product to be applied on multiple spots down the pet’s back.

While it is tempting to try and save money by using only portions of products labeled for larger pets on smaller animals, it’s a process such as this that can lead to product inefficiency.

Ensure your home and yard are treated 

Another reason for products not working is by not treating your home and yard, where in some cases 80% of the flea life cycle may occur. Read how to control fleas indoors and outdoors.

In cases of heavy flea infestations, some home products such as Advantage Carpet and Upholstery Spray kills fleas and ticks quickly and continues to kill fleas for two weeks. In spite of recent discussion in the veterinary literature, the development of widespread flea resistance is still not believed to be a major factor to clients still finding fleas on their pets.

Consider switching to oral flea medications

The newer oral flea medications are becoming very popular and with good reason — they’re even more effective than topical treatments at killing adult fleas and keeping your pet flea-free. Plus, with an oral flea treatment, you eliminate the mess of topical flea treatments and the worry about whether you’ve applied the product properly.

Have you been battling a flea infestation in your home? What are some of the ways in which you have been trying to get rid of them? 

Have pet health questions? For any medical concerns, we always recommend you consult your veterinarian. However, for non-emergency questions, you can contact Dr. Dym directly using our Ask the Vet form.

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505 Comments

  1. I think Frontline spray is the best flea killer for dogs.I always use this product for my cute dog.

  2. I have always used advantage on my two dogs (except one time when I used frontline and it didn’t work at all) and it has always worked wonders. I never had to treat my house or anything. Then all of a sudden it quit working. I tried it two months in a row and it didn’t work. This last month I tried a new medicine that I got from my local feed store. I can’t remember what its called, but its supposed to have the flea killer of one medicine and the egg killer of another. It has not worked either. Now my dogs are totally infested and I don’t know what to do. I have wood floors which I vacuum 3 times a week. I also vacuum my couch as often. I don’t know what to do.

  3. I was using Advantage on my cat and dogs right along ,intermittently spraying the carpets and yard (as a preventative)ect,and putting Flea free in their food,no Fleas for a year. After a long dry spell we got a lot of rain and my house and animals are full of fleas.Nothing seems to kill or slow them down.I’ve vacuumed(throwing bags away),sprayed,flea bathed constantly , no good. I’ve changed to frontline ,then Vectre , nothing works.There’s diatomacious earth and borax in the carpet(been there and reapplied for last couple of years)I can’t afford an exterminator . Any ideas

  4. Is it safe to administer Comfortis (spinosad) after having sprayed with Hartz flea spray(tetraclorvinphps)?
    the Comfortis is a once a month pill

  5. catherine whittingtoAugust 20, 2012 at 3:17 pm

    I have recently heard that salt is effective against fleas. Sprinkle on the dog, sprinkle on the carpet. Is this a myth?

  6. Dr. Michael Dym, VMD veterinarianAugust 20, 2012 at 5:33 pm

    I would wait 1-2 weeks and then proceed with the comfortis. Dont want to give too many pesticides too close to one another.

  7. Dr. Michael Dym, VMD veterinarianAugust 20, 2012 at 5:34 pm

    Try oral capstar and program. Also product called flea buster for home could be helpful as well which you can find on line. Exterminator though sometimes needed. Consider oral comfortis as well which often quickly kills adult fleas.

  8. Dr. Michael Dym, VMD veterinarianAugust 20, 2012 at 5:35 pm

    Try oral comfortis from 1800petmeds or program and capstar. Treat home with good product like flea busters which you can find on line

  9. Someone who brought there dog brought fleas to our house. I have ordered premise spray and I used Adams flea treatment on my dog as I was out of advantage. This was on the 12th of August. She stll has fleas. How long should I wait before applying advantage flea drops on my dog which ALWAYS works.

    Thank you

  10. Dr. Michael Dym, VMD veterinarianAugust 22, 2012 at 10:26 pm

    I would wait until August 26 before applying. Also can consider oral comfortis and/or oral capstar and program from 1800petmeds.

  11. My vet informed me that Comfortis or it’s combination product for fleas and heartworms would take care of the fleas on my cocker spaniels where others failed. Seems the fleas in this local area in Florida have become somewhat immune to Frontline and Advantage products. Tried Comfortis and fleas were GONE! I couldn’t believe how fast and how well it worked. Use Cofortis on my old girl and Trifortis on my younger male and female. No more flea issues!

  12. Dr. Michael Dym, VMD veterinarianAugust 25, 2012 at 10:08 pm

    Thanks for sharing. As a vet who also practices in Florida, I have seen comfortis and trifexis work in the vast majority of cases.

  13. Since Garlic is in the Onion Family it can have toxic affects in dogs if Given to much. Some Dogs are more sensative to it than others, so when starting a garlic supstitute use samll amounts, propaply 1/8 or 1/4 of a teaspoon depending on the size of the dog. Also It should not be given more than three times a week. This increases the chances of having a negative reaction. I use minced Garlic in water for both my dogs twice a week and never have had fleas. I also hear that yeast helps with fleas, but I have not tried it becasue I fear my dog could get bloat (which is a reaction to too much yeat).

  14. i have two cats and a rabbit and was told that advantage was safe on the rabbit as well as cats. concerned that advantage 11 is different. are the ingredients the same in both products?

  15. Dr. Michael Dym, VMD veterinarianAugust 26, 2012 at 10:00 pm

    Ingredients not same in Advantage II. I would call Bayer company and ask them about whether safe to use in rabbits.

  16. Dr. Michael Dym, VMD veterinarianAugust 26, 2012 at 10:02 pm

    Thanks for sharing. I would also refer you to great book dr. Pitcairns guide to natural health for dogs and cats by Richard PItcairn, DVM, phd for great holistic suggestions on flea control and other health tips.

  17. I thought Frontline wasn’t working because both my cats and I were itching and we had these little clear bugs that turned brown/black when they fed. I just discovered they weren’t fleas but mites. My cat is a mouser. He brought us some rat mites into the house. Now I’m using Revolution because Frontline doesn’t work on mites. So glad to have finally discovered the truth. I hope this helps someone who is battling fleas. They may not be fleas. Make sure you don’t have rat, mouse or bird mites. You’ll need different medications and different foggers for the house.

  18. lol i love love my dog and it drives me nuts to see her with fleas i feel so bad but i am tooo busy to just clean clean clean like that and it is completely un called for your dogs are gonna get fleas it will happen and yes you are gonna have to spend some money to get rid of them if you dont cut corners and you just buy the right stuff in the first place bombs and the name brand k-9 advantage – you can keep it under control before it gets to far out of your control and you have to call someone. I have a problem now and all because i wanted to save a buck now its gonna cost me a lot more then if i would of just ( like i usually do ) went ahead and bought the REAL meds my lil girl needed bottom line is its NOONES fault if the animal gets fleas its something thats bound to happen

  19. Dr. Michael Dym, VMD veterinarianSeptember 1, 2012 at 9:31 pm

    Dont be too hard on your self. Advantage is an excellent product as are other topicals like front line and oral products like comfortis and program.

  20. I have a 2yrs old Havanese. His fur is short and hypo allergenic so it’s really easy to apply flea meds. I take him to a lot of places (dog parks, dog beach, campus) where fleas may be a problem, and he always comes home with a few. Frontline doesn’t work, neither does Advantix, nor did Revolution. I still apply Frontline on him but not much really change. I don’t want to alter his routines just to avoid fleas.

    Also our house does not have a flea infestation and it had been treated for one just in case in the past.

    What should I do? I mean a flea med that semi-works is better than not giving him one at all right?

  21. Dr. Michael Dym, VMD veterinarianSeptember 8, 2012 at 11:26 pm

    Try oral medicine called comfortis or oral capstar and program from 1800petmeds.

  22. I used advantix ll on my dog and not only didn’t it work but he had a reaction. He hid under the bed for a couple of days and he seemed to lose his appetite. He’s better now but had chewed himself up pretty bad. I took him to the vet and got medication which is working very well. My vet suggested Comfortis. I am going to try it and hope for the best.

  23. Dr. Michael Dym, VMD veterinarianSeptember 15, 2012 at 6:02 pm

    Some pets are sensitive to pesticides/ Hopefully the comfortis will go better. You could also consider natural flea products like http://www.wondercide.com or http://www.cedarcide.com

  24. I’ve tried the cedarcide and it doesn’t work either. It says not to soak your pet, yet the only way the flea dies is to soak it. I’ve been combing my pet than spraying the fleas – I’ve also used their spray for the back yard – she is stilling getting them every time she goes where I sprayed.
    I think it is just a bad year for fleas and not much we can do about it.

  25. Dr. Michael Dym, VMD veterinarianSeptember 17, 2012 at 4:04 pm

    Two other great natural products to try are diatomatcious earth, which needs to be applied often, as well as Buck Mountain’s flea product. also http://www.wondercide.com a good product as well.

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