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Can A Flea Collar Make A Cat Lethargic?

Although dogs are still the most commonly kept type of pet in the areas where most of our readers live, cats are a firm second and are also seeing a surge in their popularity right now as more and more people add a cat to their home.

Cats tend to be far more independent than dogs while also not doing as many questionable things such as chewing power cables so most people who do add a cat to their home will not have many problems.

That said though, there is one thing that most cats end up suffering from at least once in their life and that is fleas.

Thankfully, there are a wide range of different flea treatments on the market these days with high-quality flea collar being one of the most common treatments for fleas on cats. Not only are they very cheap and easy to use but they also have an excellent track record of keeping both fleas and ticks off your cat.

Unfortunately though, as with all medical treatments, there is a small chance of some cats having side effects and we often see people reaching out and asking about their flea collar making their cat lethargic.

The majority of cats who have a flea collar put on them will usually be fine but a small number will suffer from the symptoms of flea collar poisoning, at least for the first day or two when you put a new collar on the cat so we wanted to publish our own article going over the topic to try and help any of our readers in this situation.

Can A Flea Collar Make A Cat Lethargic?

One of the most common symptoms of flea collar poisoning in cats is lethargy but the majority of the time, this will end up passing within a day or two and your cat will be back to normal. If the lethargy in your cat last longer than two days or other symptoms such as vomiting or diarrhea are present then we would recommend you remove the collar and see advice from your vet.

Some cats are more sensitive to the active ingredients in flea collars than others and can end up having more severe symptoms as well as possible health issues. This is very rare though whereas lethargy in a cat with a flea collar is very common for the first couple of days of use.

You also have to factor in the different strengths of flea collars available on the market too so double-checking the packaging and information leaflet that came with the specific flea collar you are using on your cat is recommended. This will give you a better idea of the possible side effects of using the treatment and the stronger flea collars on the market do tend to have a higher chance of your cat being lethargic too due to the stronger doses on the collar.

Can A Flea Collar Put A Cat Off Its Food And Water?

In addition to lethargy, some flea collars can put a cat off its food and water during the first day of treatment.

This is not as common of a side effect of lethargy though and tends to be rare but it is often recommended that if you do have a pet cat that is sensitive to flea collars to a level where it is put off its food and water then you just remove the collar and try other treatments.

Your vet will be in a better position to advise you at this point and you can book a video call with a veterinarian to get a better idea of the options moving forward.

One of the best alternatives to a flea collar for cats is a flea and tick shampoo for cats.

Although these tend not to be as effective or as fast-acting as a flea collar, they tend not to have side effects such as lethargy or your cat not eating or drinking during treatment too.

Just keep in mind that if you do put a flea collar on your pet cat and it does experience lethargy or issues with eating and drinking then it will take a couple of hours or even a day before the effects of the collar dissipate in your cat.

This is totally normal but it can catch some cat owners out as they expect an instant recovery in their cat within minutes of removing the collar but this simply is not the reality of the treatment and a couple of hours will usually be needed.

Should You Stick With A Flea Collar If Your Cat Gets Lethargic?

Only you can decide if you want to continue the flea collar treatment with your cat but lethargy is a very common side effect and often to be expected with some of the stronger flea collars on the market.

Some people will double check the packaging of the flea collar they purchased for advice or even double check with a veterinarian before making a decision.

As we mentioned earlier in the article though, flea collars are usually considered the quickest flea treatment for cats but it is not the only option available to you.

Many people who have pet cats that are sensitive to flea collars will switch over to using a flea and tick shampoo for cats instead due to the risk of side effects being far lower.

There are also a bunch of DIY cat flea treatment options available online with them having a wide range of success levels.

Just keep in mind that there is a good reason that the companies who make these anti-flea treatments for cats have not made products for many of the DIY treatments that you see online and it is due to many of them doing little to nothing to deal with the fleas on your cat so keep that in mind if you are considering one of those treatments.


That concludes our article going over if your cat’s flea collar is making your cat lethargic and we hope that we have been able to help you. Many cat owners find themselves between a rock and a hard place when it comes to treating fleas in their cat as both leaving your cat untreated and using a flea collar can have unwanted side effects. The vast majority of cat owners will choose to take action to treat the fleas on their cat in some way though as it is usually the best option to take.