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Advantage Flea Medication Allergy in Cats

Written By hannah hollinger
Published: 03/26/2017Updated: 10/28/2021
Veterinary reviewed by Michele K.
Advantage Flea Medication Allergy in Cats - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost

What is Advantage Flea Medication Allergy?

Advantage flea treatment is made by the company Bayer, and its active ingredient is imidacloprid. Imidacloprid is an effective and typically safe-to-use insecticide that kills fleas. Although it is considered safe to use, this active ingredient can cause adverse reactions by cats. 

This monthly treatment should not be used on cats younger than 8 weeks of age and should only be used by carefully following the instructions. It is to be applied between the shoulder blades of the back and you should only use the specific dosage according to your cat’s weight. 

The ingredient, imidacloprid, affects the nervous system of the fleas and paralyzes them. The fleas eventually die within twelve hours. Within just five minutes of applying Advantage, the fleas stop biting and the larvae are killed. This water resistant treatment lasts for about one month, and then needs to be reapplied. 

Many cat owners use Advantage flea medication because it is considered safe and effective. Other benefits of this medication are it is inexpensive, easy to use, and readily available in many stores.

Advantage flea medication is commonly used to rid cats of fleas and is considered safe. However, some cats develop an allergy to the medication, and if this occurs, it is important to contact your veterinarian.

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Symptoms of Advantage Flea Medication Allergy in Cats

If your cat licks any of the product or has an adverse reaction to the skin, he may exhibit the following symptoms. Symptoms of Advantage flea treatment allergy in cats include:

  • Drooling
  • Vomiting
  • Diarrhea
  • Irritation of the skin
  • Shaking of the head
  • Seizures
  • Loss of appetite
  • Lethargy
  • Difficulty breathing
  • Itching
  • Biting at the skin


There are many types of safe flea treatments available on the market today; however they can still cause a reaction if not used properly or if your cat is allergic. Other types of active ingredients in flea medications include:

  • Selamectin
  • Fipronil
  • Methoprene

Causes of Advantage Flea Medication Allergy in Cats

Advantage flea treatment is generally considered to be safe for cats; however, some cats may develop a reaction to the active ingredient. Causes of a reaction include:

  • The medication is absorbed through the skin
  • The medication can enter the cat’s bloodstream
  • The active ingredient can cause nerve damage
  • The cat may suffer from an accidental overdose

Diagnosis of Advantage Flea Medication Allergy in Cats

If you suspect that your cat is having a reaction to his Advantage flea medication, contact your veterinarian. Take the container and packaging to the appointment with you so your veterinarian can be sure of what is giving your cat problems. Your veterinarian will ask you questions about the type of medication he is on to help fight his fleas. He will then take a closer look at his symptoms and gather information about them, such as when they began and the severity. 

The veterinarian may thoroughly wash and rinse your cat to remove any of the treatment and begin giving him fluids to help with hydration and to stabilize his symptoms. He may take blood work, urinalysis, and a biochemistry profile. The blood testing will focus on your feline’s serum levels. Although blood testing and urine testing are not always absolute, your veterinarian will be able to rule out other illnesses by taking a close look at your cat’s symptoms and having the knowledge that he began having a reaction after the application of the product.

Treatment of Advantage Flea Medication Allergy in Cats

Unfortunately, there is no treatment for imidacloprid toxicity, we can only provide supportive care for the complications. Your veterinarian will explain to you what you can do at home, and will treat his symptoms. Treatment methods may include:


Your veterinarian may have already washed and thoroughly rinsed your cat to help rid his skin and fur of the toxic ingredient.

Avoid Exposure

Your veterinarian will suggest to you that you avoid all further applications of the medication. He may also suggest holistic methods to help control and get rid of fleas.

Gastric Lavage

For severe cases of poisoning, such as if your cat has ingested the medication, your veterinarian may perform gastric lavage to help rid his stomach contents of the medication. This treatment method will be followed up with a dosage of activated charcoal and possibly a dosage of laxatives.


Your veterinarian may want to keep your cat for a day or two and monitor his progress as he is on IV fluids. The fluids will help your cat remain hydrated and help further flush out any toxins.

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Recovery of Advantage Flea Medication Allergy in Cats

Most cats have an allergic reaction if they were given too much of the product or if they ingested a specific amount of the medication. Your veterinarian will communicate with you about your cat’s prognosis. Once you take your cat home, continue to monitor him for any other side effects or reactions. Be sure to give him plenty of fresh water during the day and night and monitor his drinking and urination habits. 

In order to avoid this from occurring again, you may want to consider other preventions to help control fleas. You can talk to your veterinarian about the types that are available to help your cat during peak flea seasons. If you have any questions about the main ingredients of products that can be used to help fight fleas, ask your veterinarian.

Advantage Flea Medication Allergy Questions and Advice from Veterinary Professionals





One Year


7 found this helpful


7 found this helpful

My pet has the following symptoms:
Third Eye Showing. Diarrhea Lethargy
Recent exposure to generic flea collar. My daughter's kitten wears a generic flea collar. The two cats play and wrestle together.

July 31, 2020

Answered by Jessica N. DVM

7 Recommendations

Hello- Thank you for your question. Though generic flea collars can be toxic for the wearer I do not think your cats symptoms are likely due to it. I think it would be a good idea to schedule an appointment with your veterinarian so he can be examined. I would bring a stool sample to check, and I would recommend bloodwork for him to assess the underlying cause of his symptoms. Your vet will then be able to provide an appropriate treatment plan based on exam and lab results. I hope he gets to feeling better soon!

July 31, 2020

Was this question and answer helpful?



Luke and leia


11 Weeks


4 found this helpful


4 found this helpful

My pet has the following symptoms:
I have 11 week old kittens we used advantage shampoo. They seemed ok but about an hour later they seem really sleepy I don't know if they're just tuckered out or what. Please help

Sept. 8, 2018

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