My dog has fleas

I have a sudden urge to tune a banjo. And then, of course, duel with it.

Fleas. They are insanely annoying and they are incredibly difficult to get rid of. I have seen more crazy remedies and, on the other end of the spectrum, super dangerous pesticide usage from people trying to get rid of fleas than probably any other problem. So I am going to do a roundup of what I DON’T recommend before I tell you what I do.

Before I do that, though, I want to establish exactly why we get so serious about fleas when we don’t about, for example, dust mites. Both ectoparasites, but one we go nuts about and one we basically ignore. The answer lies in the other damage that fleas do. Fleas carry a whole bunch of nasty diseases, but the two things that I see most often in dogs with fleas are hot spots and other skin disorders and (ick) tapeworm.

Hot spots are created by a dog chewing itself, or sometimes by an allergic reaction to an insect bite. The skin becomes itchy and swollen and irritated and breaks down (either because of the allergy or because the dog is chewing on itself). Because it’s deep in the fur, it can’t heal properly and bacteria go crazy. You can have a dog develop a paw-sized hole on the side of its face, above its tail, or on its leg (those seem to be where they get them most often) in just a day or two. Hot spots require prompt veterinary attention and can take weeks to heal.

Tapeworm is the result of a dog (accidentally) eating an infected flea. Fortunately, tapeworm is not directly contagious to humans (you’d have to eat a flea too; you can’t get them from dog poop), but they are nasty and they cause diarrhea and discomfort. And, of course, if the fleas in the environment are numerous enough, you or your kids could accidentally eat one and you’d get tapeworm too.

The stuff I don’t recommend follows.


Over-the-counter remedies, specifically Bio-Spot, Zodiac, Adams, Hartz, etc. OR flea bombs


All of them rely on permethrin and pyrethrins, broad-spectrum insecticides that have some pretty nasty effects on humans and other animals. You definitely want to minimize your exposure, and your pet’s exposure, to these chemicals if at all possible.

Permethrin is also far less effective on fleas than many other medications.


Canine Advantix or Revolution or ProMeris


Advantix is just Advantage plus permethrin. Why add a dangerous and ineffective drug to a system that already works? And at least one study found that adding permethrin actually lowered the effectiveness of Advantage alone. Advantix does NOT reliably repel ticks, either.

Revolution is an ivermectin-type medication called selamectin. Revolution is basically the old Ivomec pour-ons for cattle, modified to use on dogs and cats. It works because you’re pouring an insecticide on the dog and the skin is absorbing the drug and transporting it through the body in great enough concentrations that intestinal worms and heartworms are killed, and of course the skin itself remains poisonous to insects. The reason I don’t like it is that ivermectin is a pretty heavy-duty medication; it’s associated with a lot of adverse reactions. And the three things that Revolution works on–heartworm, intestinal worms, and skin parasites–require different doses of ivermectin to get dead and stay dead. You have to use about ten times the heartworm dose to kill intestinal worms, for example. So Revolution delivers a substantially higher dose than I am comfortable with. One last concern is that if it’s absorbed by dog, it’s also absorbed by you. I personally don’t want it on me.

(By the way, I DO encourage the use of ivermectin in the tiny doses necessary to prevent heartworm–but only at that dose level, and not through the skin.)

ProMeris is a new topical treatment that is getting nothing but bad press on the dog lists. I have not used it myself but everybody says it STINKS (it’s very heavily scented with eucalyptus) and if a dog or cat licks themselves where they were treated they can get (temporarily) very ill. I don’t know much about ProMeris’s flea control med, but for ticks it has amitraz. Amitraz is what is in the Preventic collar and in Mitaban dip. Icky stuff, and nothing I’d want to touch.


Essential oils, lemon


Because they don’t work.


The true herbal poisons (pennyroyal, black walnut, wormwood)


Because they’ll kill you.


Diatomaceous earth


Because it will kill you.




Because it could kill your dog




Because then your dog would smell like the lamb roast I ate every month at my grandma’s Sunday dinner. AND THAT IS BAD.

OK, yes, that was very flip. But I want to make sure you understand that NATURAL does not mean SAFE or EFFECTIVE. Fleas have been around for many more millions of years than we have; if there were a herb or scent or fruit or spice that actually killed them effectively, they would have gone extinct in the Middle Ages, which is exactly where most of these remedies are from.

Some essential oils will repel some fleas, but all it takes is one flea that will hold its nose and your dog is toast.

The true herbal poisons do kill them, but they kill fleas because they kill everything. These herbs are about a thousand times more dangerous and toxic than using synthetic flea medication.

Diatomaceous earth gets a lot of press as an effective and natural flea killer. And it probably does kill them, at least to a certain extent. Here’s why I don’t like it: DE is made of millions of tiny one-celled organisms called diatoms–or, rather, their skeletons. Diatom skeletons are like tiny razors made of silica. When you sprinkle DE on your carpet, those tiny razors shred the waxy coating of the insect exoskeleton, allowing the insect to dehydrate and die.

Great, huh?

Well, there’s a catch. Diatoms don’t really care what they shred, and there are lots of things on your body–the surface of your eye, the inside of your mouth, your mucous membranes–that are ripe for the cutting. And once you breathe it in, it will cut through the surface of your lung tissue too.

Diatomaceous earth is associated with silicosis–that’s the type of cancer that you get from asbestos, and for the same reason. Tiny bits of it in your lungs cause inflammation and damage, and over years of exposure the body can develop lesions.

Now do I think that using DE once is going to give you cancer? No, of course not. But it is NOT something I’d fool around with. If you must use DE, you should be using a respirator mask, eye protection, and a coverall. Don’t let your animals anywhere near it. And make sure every single particle is vacuumed up with a HEPA vacuum before anyone goes back in the room.

In other words, the practicality of DE as a flea control is pretty low.

Garlic is actually a pretty good dog supplement when it is used in very low doses–I would say no more than a clove a day for a large dog, which means no more than 1/4 clove for a small dog. At those dosages, it won’t repel fleas. At larger doses, you run the risk of giving the dog Heinz body anemia, which is in some cases deadly.

Hold on, gotta throw dogs in crates for the night.

I’m back, having caved on the crates and let the little dogs sleep with the girls and the big dogs sleep on my feet. Mmmmm… clean corgis on bare feet. Happy am I.

So what DO I use and recommend for fleas?

Well, I have two spot-ons and three or four pills that I think are pretty good. I recommend Advantage and Frontline if you’re looking for a topical treatment; and Capstar, Comfortis, and Program/Sentinel if you’d like a pill.

First, let me recommend that if you don’t ever see fleas, and you aren’t in an area that has ticks, don’t treat at all. Bathe frequently (as you should anyway), watch for them, but don’t stress. There’s no reason you HAVE to treat for fleas.


Let me say immediately that these are targeted toward those who have a minor flea infestation or who live in a flea-rich area and are looking to protect their dogs (but have not actually seen a flea). I’ll add specific steps at the bottom for those who are dealing with heavy infestations.

The spot-ons are first. The two I recommend are Advantage and Frontline (Frontline Plus is also OK). There is a right way and a wrong way to use them, so if you don’t want to waste $10/dose, do it right.

The key to using them correctly is understanding how they work. The spot-ons travel over the skin in the dog’s natural skin oils, then collect in the sebaceous glands (which are basically little pits full of oil) in the skin. They are not absorbed into the skin or through the skin into the body. They sit on top, in the oil.

That means that if there’s no oil, there’s no protection. And if there’s no oil, there’s no movement of the medication.

Bathe the dog to remove dirt and clean the skin. This also removes flea droppings and can cut down on the number of fleas on the dog. I don’t use flea shampoos, again because I don’t want the exposure to the pesticide. I use any normal dog shampoo at my normal dilution (NEVER apply dog shampoo straight–put a squirt in a cup of warm water, swish around, and pour that over the dog) and let the sudsed-up shampoo sit on the dog for about five minutes. This kills, or stuns, most of the fleas on the dog and they can be rinsed away.

Thirty-six to forty-eight hours later, apply the spot-on treatment. This delay is essential so the skin oils have a chance to come to the surface again. If you don’t wait, the drug won’t move over the skin properly and the dog won’t be protected.

I have found that bathing removes most, if not all, of Frontline’s protection against ticks. I don’t know about fleas. Frontline swears up and down that it isn’t affected by bathing, but I’ve got a few dozen ticks that say different. And this just makes sense–if you bathe, you remove the oil on the skin and the Frontline goes with it. The oil has to be replenished from the sebaceous glands, but a lot of the Frontline was removed in the bath and so now the concentration on the skin isn’t enough to kill ticks. I don’t let this stop me from bathing; when tick season is really bad (around here, in April/May) I let the dogs stay dirty and tick-free, but most of the year they’re getting weekly baths and I just go over them very carefully when they’ve been in the woods.

The pills (chewies, actually) are next. Again, I recommend Capstar, Comfortis, and Program/Sentinel.

Capstar is an outstanding medication that doesn’t get enough press. It is a pill that is given daily, which is why it is not necessarily in vogue. I think that vets think that people will get annoyed because they have to give it every day. Personally, I think that the daily dosing is this med’s greatest strength. It’s an almost instant kill (just about every flea on the dog is dead within 30 minutes), it’s extremely safe (even on baby puppies) and there’s zero residue. It does its job and it’s done. Nothing left on the dog or for you to touch or for your kids to get when they pet the dog.

Capstar is ideal for when you are bringing a dog into your home and want to make sure that it is not bringing fleas with it, it’s ideal for dogs or people who are very sensitive to medications, and it’s perfect for bridging between longer-lasting medications or doing a quick just-in-case treatment without leaving a month’s worth of meds on the dog.

Comfortis is a new medication derived from a bacteria; I am very optimistic about it. I am watching the lists avidly to see how dogs are reacting to it (so far, nothing bad) and, if the early adopters are happy, I will switch to it myself in a year or so. (I currently use Frontline.) It’s a monthly chew and I’ve read the studies on it. At the vet dose, it should kill all ticks for about a week and should kill fleas for between one and two months. If I were using it for fleas, I would not re-dose until I saw fleas again; the residual action of the spinosad seems to be quite lengthy and there’s no reason to double up on it if it’s still working. About one in ten dogs vomits when given the med; it needs to be given on a full stomach; it isn’t for pregnant moms (the studies show that it doesn’t kill puppies, but may affect weight/vigor, so it’s safer not to use it); and it’s for puppies over 12 weeks old. So it’s a little more ticklish than some of the other meds, but it’s working where nothing else is. I would not wholeheartedly recommend this med to everybody (talk to me in two or three years), but if you’re in a situation where the dogs are crawling with fleas and Advantage/Frontline aren’t working and Capstar is too expensive, I’d strongly consider this drug.

Program/Sentinel: This is the granddaddy of the oral flea medications. It’s got a very long safety track record, which is great. What is not so great is that it doesn’t kill fleas, just kills their eggs. It’s fantastic if you have a relatively closed environment (your dog stays home, is in a fenced yard, doesn’t visit dog parks) and you want to gently treat a small infestation or prevent one from taking hold. It will not work if the environment is heavily infested or if the dog is bringing home new fleas from elsewhere. Program is for fleas only; Sentinel is Program + Interceptor for heartworm. Both medications in Sentinel are safe and effective.

Here’s how I’d tweak things if you already have a flea problem:

1) You MUST treat the environment. In other words, the yard and the house have to be sprayed. Spinosad, the active ingredient in Comfortis, is approved for use in organic farming (in other words, it can be used and the product still labeled organic). So I’d strongly recommend using that or another organic insecticide on the yard. In the house, I’ve had very good success using Frontline spray along the borders of every room and under the couches and under the couch cushions (I don’t spray any on the seating surfaces). Frequent vacuuming of EVERY INCH (including under furniture) is super, super important. Vacuum twice a day until the fleas are no longer there. You’re going to go through a lot of vacuum bags, because you should take the bag out and put it in a plastic zip-loc and throw it out; otherwise the fleas just come right out of the bag and back into the carpet. For a bagless vac, be sure to empty the canister into a zip-loc and throw away immediately.

2) You MUST consistently kill the fleas. If you don’t want to use Comfortis, you should use Capstar right away and continue using it daily while you do the bath-wait-treat routine with Frontline or Advantage.

3) You MUST get rid of flea eggs. Wash every rug, wash all stuffed animals, wash sheets and blankets. What you can’t wash, put into sealed plastic bags and into the freezer.

And then go tune your banjo.

Good luck! And hopefully no more itchies for you or for your dog.


8 thoughts on “My dog has fleas

  1. hello, i did have a flea infestation, i have 1 dog, and 5 cats, 1 ferret and 1 guinea pig. (wish i could have more of each and then some). i wish i would have seen your site earlier, it would have helped me sooner, though spring is coming around again.
    i want to say thank you. your do’s and don’ts where an eye opener and straight forward and now i think i can lick the flea problem if it ever comes around again, which i’m sure it will. thank you, again, lesley

  2. Pingback: Bumping the flea/tick post to the top « Ruffly Speaking: Railing against idiocy since 2004

  3. This was wonderful! Thank you!

    It seems that nothing really works well against ticks. We applied advantix at the recommendation of our vet and have already pulled 5 ticks off him this season. Ticks are a much bigger problem for us around here this year. We had him on Frontline previously and will be promptly switching back.

    You didn’t mention anything about Capstar protecting against ticks. If you chose that as your treatment, how would you cover for ticks? I did read somewhere that Capstar is safe to use with other treatments like Frontline. Frontline doesn’t always work and I feel like thats alot of chemicals.

    I wanted to note that anyone who would want to introduce their pets to Comfortis may be able to find a sample of the med-free chewie at their vet. If your own vet doesn’t have one, another local one may. My dog loves it.

  4. hi great flea info, my pekingese had flea anemia his advantage
    flea protection ran out on june 16, my mom gave him a capstar on the 26 he died on july2. Would this 10 day 2 week period without flea protection kill him. He was 13 yo any comments would help

    • First of all, I am so sorry about your boy. Second, no, I would never blame capstar. It’s VERY mild and safe and can be used on tiny puppies. I hope you do find out what happened and you can feel some peace.

  5. Pingback: Ruffly Speaking = Blacksheep Cardigans » Bumping the flea/tick post to the top

  6. No im not blaming capstar that pill works great use it all the time.. Im wondering if the time frame of 10 days without flea meds could have killed him. He was on advantage for 2 years prior. He was also on enaparil for his heart. Im trying to rule out flea anemia as cause of death and it looks like that is not what killed him thanks

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