Allergic Reaction to Vaccines in Cats
Written By hannah hollinger
Published: 11/04/2016Updated: 01/21/2022
Veterinary reviewed by Dr. Linda Simon, MVB MRCVS
Allergic Reaction to Vaccines in Cats - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost
What are Allergic Reaction to Vaccines?
A vaccine is the modified form of an organism, containing the antigens for a disease that is not infectious. When the agent is injected, the immune system responds by creating antibodies for that specific infectious organism. The purpose of the vaccine is to stimulate the immune response to make specific cells to keep circulating the body. Therefore, when the feline is exposed to the virus or bacteria again in 'real life', the immune system is prepared to fight it. 
Rarely, the immune system overreacts, causing an allergic reaction to vaccines in the feline. Symptoms of an allergic reaction can be mild, moderate or severe, and vary depending on the type of vaccination received. 
Your cat’s immune system plays a vital role in protecting the body from infectious ailments to keep her healthy. Making antibodies against parasites, microbes, bacteria and viruses is one of the most important functions of the immune system. Unfortunately, this complex system cannot make specialized cells to fight every disease that invades the body, so vaccines are given to help the immune system prepare. 
It is normal for a cat to experience a few mild side effects after receiving her vaccines, such as local swelling or pain at the injection site. This is not an allergic reaction.
Your cat could be having an allergic reaction to a vaccine if they develop more worrying signs such as hives, facial swelling, difficult breathing or collapse.
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From 339 quotes ranging from $200 - $1,800
Average Cost
$650
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Symptoms of Allergic Reaction to Vaccines in Cats
An allergic reaction to vaccines in cats can be mild, moderate or severe and can appear within a few hours  after the vaccination was given. Severe reactions are usually associated with killed varieties of vaccines such as feline leukemia virus and rabies. 
Mild Vaccine Reaction
  • Fever
  • Loss of appetite 
  • Swelling, redness or pain at the injection site
  • Temporary lameness 
  • Temporary joint soreness 
  • Sneezing lasting roughly 4-7 days
  • Low activity levels 
Moderate Vaccine Reaction 
  • Urticaria (hives) 
  • Pruritus (itchy skin)
  • Swelling of the neck, eyes and/or lips
  • Redness 
  • Fever
Severe Vaccine Reaction: 
  • Breathing difficulties 
  • Diarrhea
  • Vomiting 
  • Decreased blood pressure 
  • Pale mucous membranes
  • Cold extremities 
  • Cardiac arrest 
  • Shock 
  • Seizures
  • Collapse 
  • Death 
Causes of Allergic Reaction to Vaccines in Cats
An allergic reaction to vaccines in cats is caused by an over-reactive response to the immune system. The antigen within the vaccine is used to stimulate the cat’s immune system to create specialized antibodies against the virus, bacteria or disease. However, the nature of some feline immune systems are hypersensitive and overreact to the introduced antigen. Common feline vaccinations that have been known to cause an allergic reaction in cats include vaccines against: 
  • Feline Panleukopenia
  • Giardiasis
  • Bordetellosis
  • Feline Immunodeficiency Virus
  • Feline Infectious Peritonitis
  • Chlamydiosis
  • Feline Leukemia Virus
  • Rabies
  • Feline Herpesvirus and Feline Calicivirus
Diagnosis of Allergic Reaction to Vaccines in Cats
Allergic reactions can be caused by a variety of elements in your cat’s environment e.g. a wasp sting, causing similar symptoms of a vaccine allergic reaction. Therefore, the veterinarian may want to perform a differential diagnostic exam such as an intradermal allergy test to rule out other causes. 
To diagnose an allergic response to vaccines specifically, the veterinarian will review your feline’s current vaccination history, paying close attention to which vaccines were scheduled to be administered. The vaccination history will reveal which vaccines were administered, the date of administration, and location. The doctor can then pair the medical record with your cat’s current condition to diagnose the allergic reaction to a vaccine. 
Treatment of Allergic Reaction to Vaccines in Cats
Mild to moderate cases of an allergic reaction can be symptomatically treated with anti-inflammatory drugs such as a corticosteroid and anti-histamines. A feline with a mild or moderate allergic reaction to vaccines should return to normal health within a week. However, moderate allergic reactions can worsen over time and become severe, so the feline will need to be monitored for the duration of the allergic response. 
Cats with a severe allergic reaction to vaccines need to be rushed to the veterinary emergency clinic right away. The doctor will begin administering life support to the feline including intravenous fluids and oxygen. The feline’s airways will be monitored to ensure they do not close at any time. Felines that are stabilized will likely survive anaphylaxis, but will require hospitalization for a couple days after anaphylaxis shock before returning home.
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Recovery of Allergic Reaction to Vaccines in Cats
Allergic reaction to vaccines in cats is very rare, but if your feline has a history of vaccine hypersensitivity talk to your veterinarian. The next time the vaccine is needed, the veterinarian may include an antihistamine to prevent an adverse reaction or eliminate the vaccine from your cat’s vaccination schedule altogether. The vet may also decide against giving the vaccine, depending on the specific circumstances.
 It is important to discuss vaccinations with your veterinarian to fully understand the risks and benefits that come from vaccines. In most cases, the benefits of vaccinating your cat far outweigh the risks, which are small by comparison. 
Paying to treat an allergic reaction out of pocket can be a major financial burden. Fortunately, most pet insurance companies reimburse claims within 3 days, putting 90% of the bill back in your pocket. In the market for pet insurance? Compare leading pet insurance companies to find the right plan for your pet.
Allergic Reaction to Vaccines Average Cost
From 339 quotes ranging from $200 - $1,800
Average Cost
$650
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Allergic Reaction to Vaccines Questions and Advice from Veterinary Professionals
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Domestic Short Hair Cat
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10mos
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2 found this helpful

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2 found this helpful

My pet has the following symptoms:
Vomiting Clear Liquid
Gave the distemper vaccine on the 29th of October and kitty is throwing up clear liquid. My other cat also had the same symptoms after getting her vaccine the 22nd and don't know if this is related.
Nov. 6, 2020
Answered by Dr. Michele K. DVM
2 Recommendations
Thank you for your question, I'm sorry your kitten is not feeling well. That is not a typical reaction to the fvrcp vaccine, that tends to be one that we don't see a lot of reactions to. I'm a little concerned that it's been a week and she is still feeling badly, and I think having her seen by your veterinarian might be a good idea. She may be a little dehydrated, and she may need some fluids, or there may be something else going on. I hope that all goes well for her and she feels better soon.
Nov. 6, 2020
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DSH kitten white blue eyes
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Seven Weeks
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0 found this helpful

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0 found this helpful

My pet has the following symptoms:
Severe Lameness, Obsesive Running, Dialated Pupils
18 hrs after taking vaccine, kitten went wobbly, could not control muscles. After 3 days of non coordination, she had what appeared to be a seizure...two more seizures in last 2 days.
Sept. 27, 2020
Answered by Dr. Michele K. DVM
0 Recommendations
Thank you for your question. I apologize for the delay, this platform is not set up for urgent emails. That is a very unusual reaction to a vaccine, and I'm not sure they are related? I hope that the kitten is okay.
Oct. 10, 2020
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American shorthair
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One Year
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15 found this helpful

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15 found this helpful

My pet has the following symptoms:
Vomiting
My cat threw up 20 min after he received his 1 year vaccines. The rabies, feline leukemia one, and heart worm ones. He hasn’t vomited in the last 15 minutes because I don’t think he has anything in his. How severe is this reaction?
Sept. 27, 2020
Answered by Jessica N. DVM
15 Recommendations
Good afternoon- It sounds like he is having a mild vaccine reaction or could be having vomiting from car sickness/stress of his day. I would monitor for any hives or facial swelling and return to your veterinarian immediately if that occurs. Also watch for further vomiting. If that occurs he may need some anti-nausea medication which your veterinarian can administer as well. Either way I would alert your veterinarian to the episodes of vomiting so that in the future he can receive a premedication prior to his vaccines to prevent a vaccine reaction. I hope he feels better soon.
Sept. 27, 2020
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Tabby
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Fourteen Weeks
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0 found this helpful

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0 found this helpful

My pet has the following symptoms:
Puffy Eyes
Can I give my cat something to help an allergic reaction to second vaccines? It’s mild but he has some puffy eyes and has been sleeping for hours. I live bourse from a vet. Can I give him something at home?
Sept. 26, 2020
Answered by Dr. Michele K. DVM
0 Recommendations
Thank you for your question. I apologize for the delay, this venue is not set up for urgent emails. I hope that your cat is okay. If he/she is still having problems, It would be best to have your pet seen by a veterinarian, as they can examine them, see what might be going on, and get treatment for them.
Oct. 18, 2020
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Domestic Short hair
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Fifteen Years
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6 found this helpful

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6 found this helpful

My pet has the following symptoms:
Itching, Meowing, Restless
I got my cat vaccinated today after neglecting to for several (5+) years because she has been the only cat in a strictly indoor environment. When I got home she began meowing like crazy and walking around restless and scratching and licking at the injection site.
Aug. 20, 2020
Answered by Dr. Sara O. DVM
6 Recommendations
Hello, SO sorry to hear about your cat. Sometimes these vaccines may sting. If you are noticing any swelling at the injection site, it would be best for your vet to see her. They can give her some steroids to help decrease any reaction that she may be having.
Aug. 22, 2020
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T
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Snuggle bug
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6 Months
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0 found this helpful

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0 found this helpful

My pet has the following symptoms:
Seizures
My kitten got vaccinated at the pound and now he has seizures one 2 two times a month it never last more than 2 minutes but he keeps having them I don't understand why can anyone who has experienced this problem give an advice and information on what they did and how they went about the situation I'm scared for him because they happen out of the blie
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Cat
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Sylvi
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2 Years
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0 found this helpful

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0 found this helpful

My pet has the following symptoms:
Immunizations
My 7 lb., 2 year old cat became completely immoble, had a fever of 105, would not eat, drink, or use the littwe box. I rushed her to the vet where she was given 200cc fluids,steroids, and anti-inflammatory. Have not seen her again today. HOpefully, she is just hiding and not dead. All this after 3 immunizations at one time. NEVER AGAIN!
Allergic Reaction to Vaccines Average Cost
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Average Cost
$650
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