The Seresto collar is a flea and tick collar that provides a sustained release of active ingredients, including imidacloprid and flumethrin, to repel and kill parasites. While this can be an effective way to prevent fleas and ticks on your pets, there are some potential side effects to be aware of. For example, the active ingredients could cause skin irritation or allergic reaction in some animals, such as redness at the site of application or excessive scratching. Additionally, although it’s rare, ingestion of the collar itself by small dogs or cats may result in adverse neurological effects such as depression or seizures due to neurotoxicity. Lastly, it’s important to note that chemical collars should not be used in puppies younger than seven weeks old.

Overall however, the Seresto collar is a safe and effective way to protect against fleas and ticks if there are no pre-existing contraindications or special instructions from a veterinarian. As with any medication for your pet, it’s always best to discuss with your vet before administering any type of treatment.

Skin Irritation

One of the potential side effects of using a Seresto collar for flea and tick prevention is skin irritation. The collar works by releasing low levels of insecticide over an 8-month period, and some dogs’ sensitive skin can become irritated from long-term contact with the chemical in the collar. If you’ve noticed that your dog has developed redness or bumps around the neck, it could be due to an allergic reaction to the colllar’s chemicals.

If this is the case, remove the Seresto collar immediately and talk to your vet about an alternate form of flea and tick prevention. They may recommend a topical solution such as Advantage II or Frontline Plus instead, which can provide just as much protection but with less irritation to your pup’s skin.

Loss of Appetite

One common side effect associated with the Seresto collar is a loss of appetite. While this isn’t necessarily life-threatening or particularly dangerous in most cases, it can be indicative of an underlying health issue. If you notice that your pet has lost its appetite and you suspect that the Seresto collar may be the culprit, consider trying to another flea and tick product instead to rule out a possible reaction to the active ingredients found in the Seresto collar, such as imidicloprid and flumethrin.

Additionally, if you are noticing other signs like excessive scratching or biting at their skin near where the collar rests then there might be an irritation from prolonged use of the Seresto collar. In this case, stop using it immediately and look into alternate prevention methods for fleas and ticks.


Vomiting is one of the potential side effects of a Seresto collar. If a pet experiences vomiting or diarrhea, it’s important to contact their veterinarian immediately.

The active ingredients in the Seresto collar can be absorbed through your pet’s skin and, if ingested, can cause serious reactions. Vomiting is usually an indication that a pet has ingested some of the active ingredients and not just the secondary substances found in other flea treatments.

In cases where pets experience vomiting or diarrhea after wearing the Seresto collar, it’s important to contact a vet immediately and remove it if necessary. Also be sure to record instances when these symptoms occurred so that they can be evaluated properly by a medical professional.

In nut shell

It’s important to closely monitor your pet for any signs of adverse reactions. If your pet experiences any serious side effects after being exposed to a Seresto collar, contact your veterinarian immediately. proper use of a Seresto collar can be an effective way to protect your pet from fleas and ticks, but it may also cause some side effects in certain animals, so always consult with your vet before using such a product.