Best, effective, SAFE flea treatments for dogs and cats?
May 22, 2019 12:56 PM   Subscribe

If you are also a teeny bit paranoid about this stuff and have researched current medications, please save me hours of searching about this online (once again): I need to treat the cat and the dog (separately of course). I'd like to use spot-on type treatments, and I've spent a long long long time each time I've done this in the past to search out what was effective but had the fewest reports of negative reactions. The current flea status is ...

I haven't seen any fleas on them yet (and they're both mostly white), but I spotted one on a curtain that's on our windowed front door. There are lots of stray cats in the neighborhood and around our house. I don't typically use a treatment unless I see some evidence of flea threat. (Last year, no treatment, no fleas; a couple of years ago, fleas were incredibly rampant.) I'm not worried about ticks, but don't really care if it's included if the treatment is the best choice.

They both go outside. Cat is young but adult; dog is old. Both are healthy, but the old dog has old dog ailments: leg weakness, not great sight or hearing, some confusion. She's not at the peak of fitness, in other words. Neither of them is on any medication. (I would ask my Vet / local pet shop folks, but they never seem to be as up on things as I've been, and will just go with Major Brand Name, but formulations change, and not always for the best for animal safety.)
posted by taz to Pets & Animals (15 answers total) 9 users marked this as a favorite
I have not done as much research as I probably should have, so forgive me if these things milkshake duck out, but I am very pleased with the Seresto collars. They are pricy! But they last a long time, so it evens out. I feel like they're less, um, intrusive somehow? than the pills or the drops. They were originally recommended to me by a more hippie than me friend so I'm assuming that they can't be THAT bad. My old dogs and old cat have worn them with no problem for almost a year now and so far, no fleas.
posted by mygothlaundry at 1:17 PM on May 22, 2019

I did a lot of research for this for the new puppy as there's been a lot of fuss on social media recently about the rare but serious potential side effects of preventatives. Treating and not treating both have risks and we decided the risks of not treating were worse. Vets around here are also quite unified in recommending the preventative tablet (I think it was Nexguard), and I trust their experience and training more than the collection of anecdotes on social media. I was more concerned about ticks than fleas though so I'm not sure how that adjusts the weighing.

Apologies if you already know, but I've read that cats can get very sick from licking spot-on flea treatments applied to dogs, because they react differently to it (also why you can't use the same medication for both). So definitely be careful about that. I would also avoid flea collars, which our vet said can have all sorts of nasty side effects (including for people exposed to them).
posted by randomnity at 1:21 PM on May 22, 2019 [1 favorite]

I had the experience of Advantage and Revolution working well for many years and then cease to work. Based on this earlier AskMe I tried Bravecto which has worked well this year.
posted by a humble nudibranch at 1:24 PM on May 22, 2019 [1 favorite]

The lady who cares for my dog when I'm traveling and also helps me with training strongly recommends the pills, specially Bravecto. She doesn't like the spot-on treatment, and I have to say, when I used it before I met her, I could see my dog flinched when I put it on, and tried to avoid me when he saw me with the thing. The pill works just fine, and I've not seen any side effects.
posted by mumimor at 1:26 PM on May 22, 2019

I had a horrible flea infestation in my house using topicals (and I manage an animal hospital, so I am using good products and using them correctly). Orals are the only thing I use on dogs now - Bravecto, NexGard or Simparica. Cats are trickier, probably topical Bravecto is about the best choice for flea and tick for cats.
posted by biscotti at 2:12 PM on May 22, 2019 [1 favorite]

I really would ask a vet (though I agree on pet shop employees not generally being knowledgeable). A few years back we saw signs of flea dirt and gave our cats Advantage, which we'd used successfully before, to no apparent effect. When we finally asked our vet, she said that the fleas around here seem to be resistant to Advantage now, and she'd recommend Activyl instead. We used it (and, since we had actual fleas by then, also treated the house with this desiccant powder stuff) and it worked. So there's definitely local variation, or variation over time, in what's effective, and I'd expect many vets to be aware of those trends. (She did also give our cats a pill to kickstart the killing of the fleas, but I thought that was a one time thing to kill the adult fleas currently present, rather than something we might give regularly as a preventative. I'm not read up on the pill methods, mostly because pilling a cat is usually challenging.)

There was a shortage of Activyl a year or so ago, and the vet suggested using Cheristin instead, but after a little research I was wary of it -- apparently a minority of cats can have a bad reaction to it, and the complaints I was seeing didn't seem to be coincidence/paranoia. I was reluctant to take the risk, so we basically just white-knuckled it till Activyl became available again, and managed not to get any fleas in the meantime (but my cats do not go outside).
posted by kite at 2:16 PM on May 22, 2019 [1 favorite]

I use NexGuard for my dog. No side effects, and since it's a pill there's no risk of skin irritation. It's prescription but it works great!
posted by ananci at 2:30 PM on May 22, 2019

I use diatomaceous earth to help with the house and I use advantage in the summer months.
posted by nikaspark at 3:27 PM on May 22, 2019

More anecdata: the fleas here seem immune to topical treatments. We got a serious flea invasion, everyone getting bitten. Treating our dog with Nexguard and the cat with a Seresto collar eliminated the fleas, and we've been flea-free for a couple of years despite the cat hanging out in unsavory neighborhoods where I'm sure she'd been picking up fleas before.

The cat's Seresto collar lasts eight months, then stops working and has to be replaced. The dog's getting Nexguard roughly every two months; although the recommendation is monthly, that doesn't seem necessary for us, and bi-monthly is of course half the cost.
posted by anadem at 6:04 PM on May 22, 2019

I bought the Hartz 6-7 month flea and tick collars. Done. The second time around I went to the $7.95 version instead of a dollar cheaper, they were slightly longer to fit my fat cat. My duplex neighbors got these, went one step farther and got reflecting collars. No fleas or ticks, no illness, nearly one year, in four cats total, fifteen bucks per household per year. My cats had so many fleas it took about a week for.the whole infestation to calm down.
posted by Oyéah at 7:18 PM on May 22, 2019 [1 favorite]

We have used nexguard for several years with great results and no side effects. Just works so much better than collars. And it’s a little chewy thing they love so much we call it flea candy. It was recommended by our vet
posted by domino at 7:27 PM on May 22, 2019

My cat's fleas continually became resistant to the spot treatments, and she also hates them a lot. In desperation a couple of years ago I bought a flea comb and it turns out she LOVES bring combed so much that she comes to me every evening and waits for it.

When I first started combing her she actually had fleas and about four nights of combing for 20 minutes each night took care of the live ones. I assume after that it removed eggs well enough that she hasn't had fleas again since. Highly recommended.
posted by lollusc at 4:13 AM on May 23, 2019

I swear by Seresto collars (they protect against ticks too). They really are worth the money. Never had any side effects. If your pet experiences any irritation, you can just remove the collar. If your pets experience a reaction to pills, however, that medication is still in their body for the next 30-60 days.
posted by caveatz at 10:05 AM on May 23, 2019

Seresto collars have been a complete game-changer for my cats. It's like night and day from everything else I've ever used.
posted by The Underpants Monster at 5:21 PM on May 23, 2019

There's an Australian vet who blogs under the name Dr Ferox who's done a write-up on flea treatments here:

'Confirm it really is a case of fleas, and dog or cat fleas at that. Not just a pet who’s allergic, and not a case of poultry stick fast fleas. Dog and cat fleas, Ctenocephalides spp look a bit like dark sesame seeds and will run away from light.

You can also confirm the presence of flea dirt by touching suspected dirt with a wet tissue for 15-30 seconds. Dirt remains as dirt. Flea dirt is really flea poop, which is digested blood, and will dissolve into the tissue leaving a yellow/brown halo.

Recognize that 5% of the adult fleas are living on your pet. The other 95% are eggs, larvae and pupae in the environment, including your garden, carpets, bedding, wardrobe, etc.

Not all flea treatments kill eggs or larvae. Not all flea treatments kill adult fleas. Basically none of them are very good as killing dormant pupae.

Treating the pet and the environment is equally important.


Not all medications are equally effective, and not all of them are available all around the world. There are also new ones in development and this information may be obsolete in a year, especially as the USA gets all the products before Australia does. Brand names may vary by location. So in no particular order:

Any old shampoo can drown and suffocate adult fleas on the pet. Literally any oil based thing can do this, including basically all shampoos, dawn dish soap, every other dish soap, olive oil and coconut oil. It has absolutely zero preventative properties and only works while the product is on the pet.

Fipronil based products (eg Frontline, Effipro, some supermarket brands now) are increasingly reported as ineffective.

Imidacloprid (eg Advantage and related products) based products seem to be doing alright, but it’s an old compound and will possibly be the next one to have resistance reported. It’s also implicated in killing the bees.

Selamectin (eg Revolution) is another topical medication which dries quickly and has just a little over a month’s activity. It’s still useful, but not the one I reach for in ‘problem’ flea infestations. Will also kill eggs.

Spinosad (eg Comfortis) is my go-to monthly tablet for problem infestations when cats are involved.

Fluralaner (eg Bravecto) is another medication which has proven very useful for problem flea infestations, and lasts 3 months. This naturally makes each tablet three times more expensive. I am patiently waiting for it to be available for cats down here.

Afoxolaner (eg Nexgard) has also been very useful for problem flea infestations in dogs, but most people down here chose Fluralaner instead for convenience.

Sarolaner (eg Simparica) I haven’t used myself, but should in theory be useful.

Nitenpyram (eg Capstar) is a very fast acting tablet for immediate relief only. It kicks in in 20-30 minutes, but only lasts 8-24 hours, and only kills adults.

Lufenuron (eg Sentinel, Program) only kills eggs, no adults.

Seresto flea collars are Imidacloprid based. If Imidacloprid is working in your region, Seresto collars should work too.

Other flea collars are mostly organophosphate based, which is not great for pet and not good for you either. Also the products most likely to have resistance.

Pyrethrin and Permethrin are available in many topical products and shampoos. BOTH OF THESE ARE TOXIC TO CATS. Permethrin is the worse of the two, while Pyrethrins are not as toxic and break down quicker. If you want a ‘natural’ remedy, pyrethrin is a natural insecticide from Chrysanthemum plants. It’s only going to last about 8 hours though.

Do not apply insecticides from other industries (eg horticulture, home cleaning) onto your pet. You will most likely cause a chemical burn, even if they are the same active ingredient.

You should ask your local vet clinic what is working locally. They are in the best position to know.


Now, we need to try to decontaminate your home.

Vacuum. Vacuum everything. The carpets, the floorboards, under the couch, bottom of your wardrobe, beds, clothing, etc.

Seriously vacuum everything, every few days. The vibrations encourage the invulnerable pupae to hatch so you can kill them. Plus physically removing them is always good. Remember to empty them into the bin.

Wash everything you can in hot water, after vacuuming. If you can, set things to dry in the sun to use even more heat.

You might want to use diatomaceous earth in the carpets. I’m not convinced, at all, but you don’t put it on your pet. Use it if you want, but it’s definitely optional.

You can use bug bombs, insecticidal sprays and even professional pest control if you’re really struggling.

Really heat and vibrations are key to waking up the dormant pupae so they can be killed. It’s just repetitive.

It’s also important to understand how long each flea product takes to kill fleas once they’re in contact with the pet, as most are several hours. You can have a live flea on the pet for several hours between when it first emerges from the pupae and it finally dies. This doesn’t mean the product isn’t working, just that you had a massive environmental load.'
posted by aussie_powerlifter at 2:02 AM on May 24, 2019 [2 favorites]

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