Fleas Part Three - Over the counter flea products vs. ones prescribed by a veterinarian

May 11, 2016 / Cat's Meow / 6 Comments

Keeping our furry friends free of fleas is a matter of both comfort and safety, as fleas are as annoying to them as they are to us. So, in this final blog about fleas, we thought it would be a good idea to talk about the differences between Vet and Over-The-Counter (OTC) flea products. 


We recommend Advantage Multi (which contains the active ingredients imidacloprid and moxidectin) &/or Revolution (which contains selamectin) because of these benefits:

1.Once a month topical application  

2.VERY effective against fleas

How effective? There is no need to perform environmental treatments - like powders or flea shampoo – as 98-100% of fleas are killed within 24 hours.

3.30 day residual effect to prevent re-infestation by eliminating/altering flea eggs

4.Heart worm & Parasite (ear mites, hookworms & round worms) protection

5.Can be used in kittens as young as 8 weeks old

6.Safe for the household as it will not rub off onto people after it is absorbed into the skin

7.VERY safe & reliable when used properly. This means protecting all of the animals in the household, applying to the skin in the right areas (the back of the neck) and at the right intervals (every 30 days).


You can find many different brands of flea products at supermarkets, local shopping marts, pet supply stores and online retailers.

How Effective Are They For Fleas?

Many of the available products do work in theory, so this means on paper but not in the face of an actual infestation. It has been demonstrated that OTC products, due to resistance & lack of residual effect, will affect less than 50% of fleas. This means that fleas will continue to infest both your cat and your home.

How Safe Are They?

OTC flea products are found in a variety of formulations that include: sprays, baths, collars, dips, dusts, powders & spot-on treatments. 

1.Pyrethroid based products  (made from extracts of the chrysanthemum flower) have been identified by Health Canada to be accountable for 1600 pet deaths and more than half of the 'major' pesticide pet reactions reported in the last five years. Cats exposed will experience: lethargy, vomiting, salivation, tremors, violent seizures, coma and/or death.

2.OTC flea products containing organophosphate insecticides (OPs) and carbamates are also very dangerous. If the ingredient list includes carbaryl or propoxur, the product contains a carbamate. Do NOT use!. Cats are particularly vulnerable to these chemicals as they lack the ability to metabolize them & they tend to ingest them by licking their fur

OTC spot-on treatments can cause reactions in cats for many reasons, including improper application (dog products on cats) or contact irritation. Signs to watch for include: vocalization, skin irritation, hair loss, chemical burn, inappetance (not eating) & lethargy.

What About ‘All Natural’ Products?

There are no controlled research studies to verify that these products actually do what they claim to do.  So in the face of an infestation you may find yourself & your furry friend frustrated with the potential lack of results.


Please feel free to contact us before applying any OTC product onto your animal, as we value their health & safety as much as you do. We would love the opportunity to discuss all of the flea products available and help you come to an informed decision that will benefit both you and your furry feline.

Written by Dr. Shari Muller

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We reached out to Bayer Animal Health and spoke to Dr. Rich Boisvert who stated the product Advantage II is safe to use when pregnant.  It has been approved for use in Canada by Health Canada, and treated pets do not pose a risk to humans.  I have attached a technical bulletin addressing the safety of Advantage II.   If you have further, specific questions Bayer Animal Health can be reached at (888) 663- 5326  The technical page will be emailed to you directly   

Posted by Angelina Johnstone RVT on June 13 2018 @ 8:33 am

Hi Dr Muller, My 9 year old indoor-only cat got fleas for the first time this spring. I believe it was because we got mice in the house over the winter. The flea problem quickly got out of hand because I was not expecting it at all. Our cat doesn’t go outside and we have zero carpets in the house. By the time I realized we had a problem, I there were fleas hopping all over the couches and my 2-year-old son and I were covered in bites. The vet recommended advantage II for cats, and that’s what I bought. I got a 4-pack and plan to keep treating her monthly all summer. I opted not to have the house sprayed as I was worried about pesticide exposure for my son and myself (I’m 20 weeks pregnant). I instead vacuumed every other day for a couple of weeks until we stopped getting bites. The problem seems fairly well controlled now, but I’ve been worrying a bit over exposure to the pesticides in the advantage treatment. I applied it to my cat and some of it certainly got in my skin in the application process. Also, I’ve been cuddling her and rubbing her and it just occurred to me today that I might be exposing myself and my developing baby to the pesticides. Is it safe for me to continue using this treatment on my cat while I’m pregnant? Thank you for any help!!

Posted by Alison on May 30 2018 @ 7:19 pm

We would recommend you speak to your veterinarian to make a specific recommendation for your cat but in general either Advantage Multi or Revolution work great for kittens.

Posted by Village Cat Clinic on September 12 2017 @ 3:44 pm

What do you recommend for kittens??

Posted by Robin Montgomery on September 9 2017 @ 6:08 pm

Hello Sarah Sorry to hear your having problems with fleas.  We would recommend that you call your veterinarian so they can recommend a plan specifically for your cat.  Most of the time this will consist of a topical veterinary product that will kill adults.  Typically you will need to use for at least 3 months.  They can also go over the products that you've purchased and figure out will you why they didn't clear it up for you.  Shampoo's for example will make your cat feel better but don't have any residual activity so they offer no protection.   I hope this helps.

Posted by Village Cat Clinic on May 15 2017 @ 3:24 pm

Hello there My cat is 6 month old and recently has infested with fleas so I bought shampoo, spray, collar and the drops for antifleas from Walmart but after tried on him he still scratching and still have them. What should I do please? He has all the shots though.

Posted by Sarah on May 12 2017 @ 11:17 pm