When it comes to controlling fleas and ticks, the Seresto collar can be highly effective; however, there are a few reasons why the collar may not be working as effectively. Below are some of the most common issues experienced by owners that prevent the Seresto collar from working optimally:

1. Not properly activated: Sometimes a new Seresto collar will arrive with an insufficient level of active ingredients to protect your pet adequately. When this happens, it must be reactivated using a hot water container and left in there for 15-20 minutes before being placed onto your pet’s neck.

2. Not replaced when necessary: The effects of the active ingredients in the Seresto collar last up to 8 months but will eventually start to reduce over time making them no longer effective after that period has passed. To get optimal protection from these collars, they should always be replaced at least once per year (gold standard is 6 months).

3. Too loose/loose fit: To work effectively, the Seresto collar needs to have a snug fit on your dog’s neck so that all areas are covered. If it’s too loose or if it fits loosely against your pet’s neck then efficacy will be reduced significantly as fewer of its active ingredients are emitted into their fur and skin leading to an inadequate level of protection against fleas and ticks.

4. Overwashing: While occasionally washing your dog won’t necessarily lead to an ineffective Seresto collar; however, excessive washing – without replacing immediately thereafter – can negate some of its effectiveness due to being scrubbed away during the wash process.

By ensuring that you follow proper activation procedures, join times and wearfitting practices, you can ensure that your pet is getting all-round protection from pesky pests like fleas and ticks as well as other external parasites like mites with their Seresto collar.

Check the Collar Fitting

If your Seresto collar isn’t working as it should, one of the first things you should check is the fitting. If your pet’s collar isn’t fitted properly, it won’t be able to do its job effectively. The Seresto collar is designed to fit snugly around the cat or dog’s neck seresto-collar with no overlap and one or two finger-widths of space between the skin and the inner edge of the collar.

You also need to ensure that your pet has not chewed off any parts of the collar or damaged it in any other way. If they have, then it’s likely that flea protection won’t be effective until you replace it with a new one. You should also make sure that you choose the correct size for your pet so that it fits comfortably and won’t slide off their neck!

Make Sure You’re Administering it Correctly

One of the main reasons why the Seresto collar isn’t working could be because you’re not administering it correctly. The Seresto collar must be applied correctly in order to ensure it’s effectiveness. For example, the collar has to fit snugly around your pet’s neck without being too tight. If it is too loose, then the active ingredients won’t make contact with your pet’s skin and won’t be effective at killing fleas and ticks.

Additionally, you need to make sure that you are replacing the collar every 8 months or sooner if needed is necessary for good results. The active ingredients on the collar will start to degrade over time, so replacing as directed will help maintain maximum effectiveness.

Finally, make sure you’re using other flea and tick prevention protocols such as vacuuming your home often and treating your pet’s bedding regularly. By combining these methods with a properly applied Seresto collar, you should have good results in keeping fleas and ticks away from your pet!

Consider Other Causes of Inadequate Control

While the Seresto collar may not be working due to incorrect sizing, there may be other factors at play that could cause inadequate control of fleas and ticks. Make sure you consider other causes such as:

1. Poorly Fit Collar – The collar may be too tight or too loose, preventing your pet from getting the full protection from it.

2. Not Replacing Regularly – For maximum efficacy, replace the collar every eight months for cats and every five months for dogs.

3 . Sensitivity to Treatment – Some pets can have sensitivity or even an allergic reaction to this type of product and therefore won’t get the full benefit from it.

4 . Low Product Quality – It’s possible that counterfeits exist so make sure you purchase directly from a reputable retailer to ensure quality.

Check the Expiration Date

One of the most important things to check before wondering why your Seresto collar isn’t working is the expiration date.

The Seresto collar contains very powerful insecticides that protect against pests and parasites. However, over time these chemicals will break down and become ineffective. This means that if you have a Seresto collar that has gone past its expiration date, then it won’t work properly.

To ensure your Seresto collar is effective, always check the expiration date before putting it on your pet. If the expiration date has passed, discard the old one and get a new one. You can also check regularly for damage or wear-and-tear, as these could reduce the effectiveness of the product even if it hasn’t expired yet.


If your dog has flea or tick problems after using a Seresto collar, you should examine the product and ensure it is being used correctly in order to ensure maximum effectiveness. Additionally, you may also have to consider other health factors that may be affecting your pet.