Flea Medication Not Working on Pets

For a fool-proof plan to eliminate a flea infestation, it takes patience and weeks of treatment including treating your pet and home environment

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

First, I make sure that they are correctly applying the topical flea medications. It is easy to forget that 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. It’s also important to properly follow product label directions, which for some products like Advantage II for large dogs require that animal guardians apply the product in multiple spots down the pet’s back. While it is tempting for animal guardians to try and save money by using only portions of products labeled for larger pets on smaller animals, it is a process such as this that can lead to product failure. Another big reason for product failure involves not addressing home flea relief for the pet, where in some cases 80% of the flea life cycle may occur.  Consider using Premise Treatment for indoor home use.

In very heavy infestations, I will often recommend a professional home exterminating service. My favorite home products include borate based products such as Flea Busters, which can often dry out or dessicate the various flea life stages. In spite of recent discussion in the veterinary literature, the development of wide spread flea resistance is still not believed to be a major factor to clients still finding fleas on their pets.

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?

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  1. Stop poisoning your pets people. From my experience with SEVERAL flea meds on a dog and 2 cats my opinion is: they DO NOT work. Companies that make topical flea and tick products know this but like the big pharma are here to rip you off. I use Diatomaceous Earth (food grade) in our basement and comb my cat everyday (dog is gone and other cat is outside) and that’s the only thing that’s been working. Does it eliminate fleas 100%? No. But better than poisoning my pet! I comb until i get no fleas. I usually get about 5-6 a day (outside cat comes in to eat and that doesn’t help, when she’s gone we won’t have that problem)

    • Serafina, Please, just don’t let your pets inhale the Diatomaceous Earth; its microscopic cells (diatoms) have razor sharp edges that can literally cut your pets’ lungs to shreds, causing a long, painful death during which they can’t breathe. I lost a cat this way, as did a friend who sprinkled it on a carpet in a room where she kept a cat. Another friend of mine puts a little warm water in her cats’ wet food then mixes the DE in with that so it dissolves. I’m against poisonous stuff on my animals, but have had success with K9 Advantix for the dog, and Revolution on the cats (who don’t go out, so they don’t need tick repellent). I also use a premise spray in the house once a year. While spraying, I put the animals outside and leave them there for an hour after spraying. No one has had any adverse reactions, although I know it’s always a possibility.

    • Dr. Michael Dym, VMD veterinarianSeptember 8, 2014 at 3:36 pm · Reply

      Thanks for sharing Serafina.

  2. Fleas will still jump on and bite your pet even after treating. Fleas will get picked up while your pet is outside. This is how topical flea treatments work. A flea needs to bite the animal in order to ingest the poison. The flea dies and the cycle in your house is shortened, but as long as animals go outside you will never be flea free. Vacuum the floors and wash bedding (yours too) regularly to help stop the indoor flea cycle.

  3. I use advantage II on my kitties. Recently I have had problems with fleas returning before the next dose (EVERY 30 DAYS) is due. I read where it works UP TO 30 days. If this is the case, how soon can I re-apply advantage?

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  6. Hi I applied some frontline on my small dog about the weeks ago. With in this time I realized it was applied wrong so we gave her a bath like two days after we applied it wrong. I’m wondering even I can put more on..

    • Dr. Michael Dym, VMD veterinarianSeptember 28, 2014 at 5:07 pm · Reply

      I think it is ok to reapply in 2 weeks in this situation from time of first application. You can also consider oral flea meds like comfortis from 1800petmeds.

  7. Frontline Tik is worthless I have appled all three tubes on my Dog and he is still invested with fleas. I have no problem getting it to his skin he is a short hair Chihuahua. I am not pleased at what I paid for it and yet he is still covered in Fleas. I have been getting better results by bathing him. At this Point I will be glad when we have a Freeze. After 3 applications in less that a month, I would not waist my money on any frontiline products again. Not Happy.

    • Mary, It’s true that Frontline doesn’t work anymore on many animals, mine included, but PLEASE don’t apply this or any other product so often. 3 applications in less than a month could be poisonous or even fatal for your dog. Try Confortis or Advantix II. I use Advantix on my chihuahua (be sure to get the “small dog” dosage), and she’s been flea and tick-free for a couple of years. You have to treat the house, too, though, or the fleas living there will just keep reproducing and bothering your dog. If you don’t want to use chemical premise treatments, you could use salt and baking soda, which seemed to work for us. Look up online how to do the salt/baking soda routine. Good luck.

      • It said on the Box apply again if necessary I did not do them all at once, I waited about 1 1/2 weeks and Applied Again, poor little guy was covered. We have sand fleas out side it was so dry here and he would not have a flea on him, and as soon as he come back in, covered in them, little itty bitty black sand fleas. I keep the house sprayed haven’t seen them in here. But when I go outside they get on my feet, so I spray my feed with repellent and haven’t had that issue yet. I can not afford to buy something else right now, that cost me $50 and times are hard. I figured it would last me three months. So we are doing the bathing every 3 or 4 days, Haven’t seen as many fleas just a few. Thank you for your Help and the Luck.

      • Dr. Michael Dym, VMD veterinarianOctober 13, 2014 at 3:46 pm · Reply

        Thanks Pamela for the wonderful and helpful suggestions. I agree focusing on the home and another preventative like comfortis is great idea.

    • Dr. Michael Dym, VMD veterinarianOctober 13, 2014 at 3:47 pm · Reply

      See Pamela’s excellent response. Definitel no more front line in my opinion. I would go with oral comfortis.

      • He can not take the Comfortis, he has Seizures and as I said can not afford to buy something else right now. I feel Like I should ask for my money back.

        • Dr. Michael Dym, VMD veterinarianOctober 14, 2014 at 4:05 pm · Reply

          I certainly understand. Consider natural flea control such as food grade diatomaceous earth or possibly the wonderful natural products on http://www.wondercide.com

        • Apparently Money must not be an Issue for you, I spent over 180 dollars of Flea Stuff for my Animals through this Site. I do not have the money to buy anymore thanks to the wonderful greed of this Country. I have mixed my own, with Vinegar and Dawn Dish Soup, one cup Each mixed in a bottle and then I bathed him with it. Haven’t seen a Flea Since and it did not cost much. Thank you. I doubt If I order from here again, I would rather make something myself that i know is safe than to use something else on my Dog. He was miserable for over a month with those Sand Fleas. As I stated before I figured the 3 tubes would last me of the Frontline for 3 months and if it doesn’t work anymore why are you selling it on this Site. Ban it and stop it from being on your Site if you truly care about Animals.

  8. Pet are a part of the family and to take care of them in a proper way is lot more important and specially you have enough knowledge about the pet infections to prevent the disease, the best way is to vacuum all home properlly.

    • ADVANTAGE for indoor cats did not work on my two cats. After a week of still getting fleas off them I called the hot-line noted on the box. I followed all their instructions which included re-dose in 2 wks from original dosage, vacuum every day, use pet-friendly flea spray all over house and their beds. NOTHING WORKED; wrote Bayer (the maker) and sent receipt with my note. They never acknowledged it, nor did I get a refund, its been 4 weeks.
      At advise of Vet, I have switched to Revolution and plan to stick with it every 4 weeks even though it costs a little more.

      JOHN, you are right…it’s very important AND I VACUUMED EVERY DAY FOR TWO WEEKS; plus sprayed with an eco-pet-friendly flea spray for carpets. I hope by switching to Revolution my cats can get back on track to not having this south florida flea problem.

      • Dr. Michael Dym, VMD veterinarianJanuary 7, 2015 at 6:56 am · Reply

        I have found topical front line and advantage dont work as well as they used to, especially in areas of heavy infestation like Florida year round. While revolution is an excellent product, some clients will even have to use comfortis on top of that in high exposure areas. Treating home also key.

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  10. ADVANTAGE for indoor cats did not work on my two cats. After a week of still getting fleas off them I called the hot-line noted on the box. I followed all their instructions which included re-dose in 2 wks from original dosage, vacuum every day, use pet-friendly flea spray all over house and their beds. NOTHING WORKED; wrote Bayer (the maker) and sent receipt with my note. They never acknowledged it, nor did I get a refund, its been 4 weeks.
    At advise of Vet, I have switched to Revolution and plan to stick with it every 4 weeks even though it costs a little more.

  11. What happened to my prior post?

    Bottom line…ADVANTAGE did not work for me, even after calling hot-line and following their instructions which included re-dose after 2 weeks. Bayer, the manuf., did not give me a refund nor did they acknowledge my request. I’m going back to REVOLUTION, even though more expensive.

    • An “all cats” Vet in Jacksonville just told my friend that the best product working NOW in FL for large cats with fleas is ACTIVYL drops; needs Vet Rx or they order it for you. Gonna check into this.

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  13. AcuGuard is too big to put in the back of my cat’s throat but when I crush into some wet food that she normally dives right into, she won’t touch it. Revolution didn’t work this past month so I traded off for the AcuGuard pill in hopes of seeing a change. How do you get your cat treated with the AcuGuard pill? One of my cats is allergic to flea bites and gets super irritated and licks her back constantly if she gets a bite, I feel bad for her. Wish fleas were a thing of the past but with other neighborhood cats and random possum appearances I know they will never fully disappear. Ugh. Would love some feedback/suggestions!

    • Dr. Michael Dym, VMD veterinarianMarch 18, 2015 at 1:53 pm · Reply

      I dont have much experience with this product. My personal preference in cats for oral pills is comfortis.

  14. You know what really grinds my gears? Hearing vets say that the problem is not that fleas have gotten immune to the meds, but that you need to vacuum more often! I have 2 cats and 1 dog and never had a problem eradicating fleas using only Advantage II… until summer 2014. Since last summer, I’ve tried Advantage II, Advantix, Frontline, Hartz, Bayer, every topical treatment available. All 3 pets have expensive, supposedly the best, flea collars. We have been giving them all flea baths at least every 3 weeks which is causing one of my cats to have a skin rash. Diatonaceous earth all over yard: no effect. Then tried spraying Sentry all over yard: small reduction in fleas. I have 3 flea traps around the house: they catch fleas, but I still find just as many on my pets. My wife washes all our bedding a few times a week. Heres the kicker: WE DONT HAVE CARPET. Not even rugs… we got rid of all the rugs because of the fleas!!! And we vacuum the hardwood floors with our bad-a$$ Dyson at least twice a week.

    I’m not looking for anyone to give advice because I am convinced there is none that anybody can give. In the past year, 7 houses on my street have gotten tented and each time another house gets fumigated, our flea problem gets worse. I don’t want to fork out a few grand to get tented because I have noticed that 2 of those houses got tented a second time a few months later. Obviously it didn’t work for them.
    I have seriously considered shaving all the fur off of my pets, but I know that is not the correct means to this end. My family and I are just gonna have to accept the fleas and learn to live with all the bites and itchiness until some smart person finds a solution to this ridiculousness. We need a biological weapon like flea-ebola or flea-plague.
    My reason for posting this rant is so others that are as frustrated as myself can see that they are not alone. We are not gross, un-clean, un-caring pet owners! We just don’t stand a chance against fleas from planet Krypton.

    • Dustin, I had the same problem with my cocker spaniel – NOTHING worked, and our poor baby is allergic to flea bites. You’re correct about the fleas becoming immune. We finally shelled out the $100 for a six-months supply of Comfortis pills (crushed easily and put in his food), and it worked beautifully – for a few months. Now it seems it quits being effective a week or two before the next dose. Ugh!!! We may try switching to Trifexis or Nexgard, both of which are more expensive than Comfortis. You do what ya gotta do. Good luck, Dustin.

    • Dr. Michael Dym, VMD veterinarianMarch 18, 2015 at 1:07 pm · Reply

      Maybe try the environmental products from http://www.fleabusters.com Have been around a long time.

    • Thank you, Dustin!! You summed up my frustration completely. I wish I had advice for us. I’ve had my cat for 13 years and my dogs for 10 years. Never a flea problem until this summer. I’ve tried Flea Baths, Capstar (which does actually kill live fleas but the eggs remain a problem), Revolution, Frontline, Flea Collars, had my entire home professionally treated. Now I just spent more money on Advantix II. Something has to work. The pets are itching and I have bites all over my feet up to my knees (at last count over 60 bites!!).

      Miserable in Florida.

  15. The fleas ARE becoming immune. When advantage first came on the market back in the 80s I had an infestation in the house that disappeared after I treated my cats. Both it and frontline simply aren’t as effective as they used to be. The drought conditions here in California are not helping. Fleas used to abate during the cold, wet winters but, with a near year-round summer for the past two years that is no longer happening.

  16. When I noticed a few fleas on my cats I got them a flea coller. The fleas got worse. Then I got the powder. ….more fleas. I saw someone online saying dawn dish soap kills fleas. Success!…..kind of. First I use a flea comb knocking the dislodged fleas into a glass of water then I cover my cats head in tear free baby shampoo, the body in dawn dish soap and wait a min. I Use a flea comb again while I wait. Then I hold my poor cats body (not the head!) Underwater for 6 min to down underwater to down more fleas. After I rinse and wrap my very unhappy kitty in towel I scratch my kitty’s head herding the surviving fleas to the nose and mouth were I can pick them off and drop them in water. Flea comb let dry then flea comb again.
    Sadly this does not kill the fleas in the carpet. I put a plate of corn syrup on the ground a few days later it’s covered in fleas. I’m going to try baking soda wish my luck.

  17. I don’t understand why would anyone try to ‘save’ some money, by buying larger and using only portions of products labeled for larger pets on smaller animals? One little mistake and your pet may be ‘over-dosed’ and next time ‘under-dosed’?

    We have small dog, but we apply the product in multiple spots (2-3) down his back .. just in case … and it works …

  18. If someone have a pet with long hair and plan on cutting/trimming dog’s hair – first cut/trim dogs hair, wash your dog and after drying him, apply medications like these. Don’t apply the medication and then trim the dog …

    just my 2c

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