Cats can develop allergies or “intolerances” to ingredients commonly found in commercial cat foods. The most common ingredients that cause allergies are chicken, fish and corn, as well as grains and dairy products. However, an allergy can develop to any protein to which the cat is repeatedly or constantly exposed, and sometimes, allergies develop over time.

Symptoms of food allergies

Food allergies may manifest as itchy skin, rashes or excessive grooming, or as digestive symptoms, including vomiting or diarrhea. Digestive symptoms often mimic those of inflammatory bowel disease.

Diagnosis of food allergies through a food elimination trial

Food allergies are diagnosed by conducting an elimination diet trial. There are currently two approaches for these trials: a hypoallergenic diet, or a novel protein diet.

Hypoallergenic diet

There are several hypoallergenic diets on the market, available only from your veterinarian. These diets are made from hydrolyzed proteins. They use a conventional protein source like chicken, but the protein is broken down into molecules too small to stimulate the immune system. It goes without saying that these diets are highly processed, and only one is available in canned form. All contain by-products and fillers.

Novel protein diet

Novel protein diets used in a food elimination trial must contain a protein that the cat has not previously been exposed to.Unfortunately, with pet food manufacturers coming up with ever more exotic diets, it is becoming increasingly difficult to find a truly novel protein. Typically, novel protein diets would be venison, rabbit or duck based. Depending on what your cat has been eating, you may need to reach for even more exotic proteins such as pheasant or even kangaroo.

How to conduct the diet trial

With both methods, the new diet needs to be fed exclusively for a minimum of 12 weeks. This means no treats, unless they contain only the same novel or hydrolyzed protein, and no table scraps. You will need to check the ingredient list on any supplements you give, since many pet supplements have chicken or beef flavoring added. If you give medication with pill pockets, you will need to find an alternate method of giving your cat’s medication.

If a food allergy is present, cats will start responding to the elimination diet within four to six weeks, but it is important to continue the trial for the full 12 weeks. If the trial is successful, cat guardians are asked to return to the food that was fed before the trial. If symptoms return, a food allergy has been confirmed. Many cat guardians won’t be willing to go back to the original diet to confirm an allergy if they’re seeing an improvement or complete resolution of their cat’s symptoms. Cats can stay on these hypoallergenic or novel proteins indefinitely.

Holistic treatment of food allergies

Cat guardians who would prefer a more natural approach can use raw or home cooked diets using novel proteins for the food elimination trial, or as a long term solution. Work with your holistic veterinarian to determine the best approach for your cat. There are anecdotal reports of food allergies resolving by simply switching to a raw diet even without the use of novel proteins.

Homeopathic remedies can help strengthen the immune system so it will no longer react to the substance causing the allergies. Work with a veterinarian who is trained in homeopathy. Randomly choosing homeopathic remedies, especially combination remedies, tends to not get very good results.

Spirit Essences Skin Soother can provide relief from the itching and anxiety that can go along with allergies and can help balance the cat’s energy system.

Treating allergies can be frustrating, and finding a solution can take time.

Photo: istockphoto

41 Comments on Food Allergies in Cats

  1. Thanks for the helpful article. I think the last comment was almost 1 year ago, so I am late to the info. My cat has chronic loose, very stinky stool, and she has licked her belly and inner back legs nearly bald. The skin is soft and not red at all, just almost bald. This isn’t stress or anxiety – she is a happy, relaxed cat and shows no other signs of discomfort. I have noticed earlier skin sensitivities from when I applied Revolution flea ointment and there was temporary fur loss at the spot of application. I was feeding her a kibble mix of 95% Merrick’s Before Grain (chicken) and 5% Hill’s prescription oral care (which contains some grain filler), plus a daily spoon of wet food. I varied the wet food between Royal Canin Intense Beauty, which her foster family before me gave her without problem, and various Natural Balance Platefuls packets in chicken or salmon or fish. I first eliminated just the Platefulls packets, and noticed her “movements” are far less stinky, yet still loose. I’m now slowly transitioning her to Natural Balance L.I.D. duck and green pea in both kibble and wet food, and will do a food trial once she’s fully on it, and we’ll see.

    • Hi,
      My cat Mika had the same problem, though he did lick any part bald. He used to have stinky poo and rough hair. Few months ago, we went to a different vet and she recommended Hydrolyzed food. Since then, he had improved so miuch. He no longer had stinky poo, his haie coat is thick and shine beautifully. Hes is much more playful like his oldself, no longer reclusive. I can’t be any more happier for him. The food is more expensive than the normal food but i found it worth every penny.
      I just want to share because Mika had this problem for years and I have tried all kind of foods including other prescription diets with him until i found Hydrolized food.
      For all the cat mamas out there that have the same problem, please share this. I only wish i had found this info sooner so my cat didn’t have to suffer that long….

      • A hydrolized protein diet will work well for some cats, and I’m glad it’s working for yours, Van. Unfortunately, the ingredients in those diets aren’t the greatest, but sometimes, you have to compromise.

    • stop using Royal canin, my cats are now on detox diet thanks to royal canin, they was vomiting and even see things wasn’t there, in having a hard time with the male adjusting to change of food, he still showing sings of allergy but not vomiting, I guess take time , I don’t take him to vet, I read all of bad things from royal canin since I stop giving them that food no vomiting, almost a week.

  2. Hi Ingrid,

    So we are thinking about rescuing a kitten to keep my 7 month old cat (Luna) company. She may or may not have a food allergy- Won’t know for a couple of weeks if we will have to put her on a novel protein trial run. If I were to rescue a young kitten – probably around 2 months old – is it safe to feed her what Luna would get if she had to be on a special diet- I was thinking about the Mauri brand (brushtail or kangaroo) or Natures Variety Limited Ingredient – they don’t have rabbit in can though which is disappointing. I can’t do turkey as a novel protein because that was an ingredient in one of her Nature’s variety instinct also.

    I am just thinking ahead here just in case her ear infection is due to a food allergy and how this will play out if we get a companion for her. I’m thinking the easiest way to go about this is feed them the same thing- So is it safe for the 2 month old kitten to eat ONLY Mauri can food (brushtail or kangaroo) or Natures Variety Instinct limited ingredient (Duck)?


  3. GG -i would say forget the stress and expense of invasive IBS tests.
    Vets always say IBS or lymphoma with a vomiting cat, thickened intestines and diarrhea
    and its because they lack training in nutrition and diets.

    Cats like people have food sensitivities and it is extremely common.

  4. I just wanted to thank you for this great explanation of elimination diets and novel proteins. It’s possible that I will need to do something like this with Katie in the near future based on her last couple of ER vet visits. If she continues to show symptoms in the near future again (not eating as she normally would, loose stools, vomiting) the next step will be figuring out if there’s a food allergy and what it is. From what I understand, if that’s not it, she may need to be tested for IBS. But I don’t want to go down that road unless we have to. It sounds like the test for that is rather invasive.

    I see you’ve written about IBS before…I’m going to check that out next.

    As always, thank you for the great info. I love my vet and she’s usually great at explaining things, but her explanation of the whole allergy thing was quite complicated. You did a great job of explaining it.


  5. Hi, my Bombay has a very serious food intolerance and I’ve tried everything with her. Can anyone offer some advice? The vet said to just keep her on Hills z/d for the rest of her life but she refuses to eat it and she has got so skinny. I’ve just started giving her slippery elm bark to see if it will soothe her tummy but I’m out of options right now. If anyone can help it would be much appreciated

      • Do you know what food your kitty is allergic too? If you haven’t gotten a blood panel for allergies yet it would be worth getting those can tell you alot. My kitty just happens to be allergic to quite a few foods., Chicken, Fish, Eggs. I always heard go to a 1 protein ingredient food or a LID. There are a lot of them out there.

        • Hi,I know this is a very late reply but if anyone else is having this issue, my Maine coon had the same problem with hills zd, just getting skinny and not eating it, so the vet asked me to feed him nothing but cooked duck for 2 weeks and some probiotics, obviously this isn’t enough time to resolve the diarrhoea but he seemed much brighter and stopped dripping and trumping The vet said this is what he was looking for and to feed him cat food with just duck as the protein and I should start to see results after around 8 weeks! Fingers crossed because I put him back on normal cat food after the trial and he went bad again straight away

  6. My Picasso was diagnosed with IBD a year and a half ago, and passed away on September 11, 2013.

    A biopsy of his intestines “proved” IBD, but I wonder if food allergies were to blame.

    I tried a novel protein diet initially – but he was resistant to eating the pate form of canned food, which is how most of those diets are sold. I tried heating it, mushing it, feeding him, etc…no go!

    What he did like is shredded chicken. I made it in the crock pot for him weekly, and added canned pumpkin. He was able to eat a little grain free chicken kibble, too – he begged for it.

    In the end, he was so skinny. It seemed like no matter what he ate, it was not being absorbed. His vomiting had stopped, but he was very restless and always hungry.

    I hope I didn’t prolong his pain by trying multiple diets. If you have any time to publish a good article for cats with IBD and or IBD/food allergies, that would be so helpful. The information out there is hard to find.

    • I’m sorry about your Picasso. IBD is still such a misunderstood disease, and you’re right, there isn’t much new information about it. I will definitely continue to look for new findings, and publish them here on this site as they become available.

      • Thank you. His nickname was “Picky,” and that’s what he was, about his food. He was only 9 and it devastated me, because he was my baby. He was also the glue that held my feline family together. My youngest, however, was Picasso’s special buddy, and is taking over the role of trouble maker/peace maker/snuggler, to a certain degree. I still miss my crazy tuxie, though, and which I had more knowledge or money (to be honest) to do better by him.

  7. I adopted a 9-month-old female Chartreaux on June 1st (thinking she was a Russian Blue with a bit of tabby until online friends set me straight on her breed). She would scratch her shoulders, behind her ears, & her face a great deal. She’s my 11th cat I’ve had in my life & I had never seen any of my other cats scratch so much. We have a dog & a 15 year old daughter so at first I thought it was anxiety causing Bluestar to scratch so much. However, after 2 months of this I began to wonder if it may be an allergy & prayed it wasn’t the dog (or us!). The vet first treated the itching by giving her an injection of cortisone, which is a steroid. Steroids eventually destroy a cat’s kidneys so he said 1 more injection is possible, then we have to try something else. Now, the only constant between her foster & shelter care & our home was her food. She was on Pro Plan Salmon flavor. Under my own guidance I switched her to Friskies for indoor cats. The injection wore off in 2 weeks, but she had been on the Friskies for about a week by then & when the shot wore off she had completed her week long transition to the new food. I took her back to the vet for a follow up & she gave her fish oil to be placed on her food to help with the skin, but no lesions were found, even though previously Bluestar had torn a hole in her left cheek. She didn’t like the fish oil on her food & wouldn’t eat so I had to stop using it, but after another week on the Friskies she is now no longer scratching – just once in a while like a typical cat. I’m very glad I followed my own intuition & changed her food. It seems a food high in protein like Pro Plan (which is 40% protein) just wasn’t something she could tolerate well.

  8. Well I know to well about food allergy, my pure bred Bengal cat started to get crusty ears on the inside of them, I also noticed bald patches throught her body, so I called the vet and had her checked he couldn’t find a cause for this so just gave her a steroid shot and within days it was gone. Weeks go by and it started up again, but this time I noticed she wasn’t playful and would sleep all day, and also had the shivers, of course I freaked out and brought her to the emergency room, they couldn’t find anything and decided to run every darn test imaginable, which cost nearly 1,000, so I said sure go right ahead but still nothing unusuall to be found, so the vet gave her another steroid shot, and in days was back to herself, now remenber she didn’t have any stomach problems, everything was normal, then about two months later same old thing high fever with no explanation, now the steroid shots were constantly used, which I really couldn’t stand it, since it is so bad for cats I decided to do this on my own and change her food, she was eating Royal Canin, thinking that was good for her, I changed her food to a grain free diet that consist of high omega which was really only found in fish, we tried this for a month,and I slowly noticed her playfulness comming back, and her coat so soft and shiny, but most important no bad crusty ears, my vet couldn’t belive the change, we struggled for almost two years of not knowing what the problem was, but I’m glad to say she is doing fantastic and has not needed a steroid shot. The best advice that I can give is trust your instincts, I did and I’m. so glad that I went with it.

  9. I just have to say that I have a 14yr old tabby cat named Honey. When I say she has food allergies or inflammatory bowel disease is the just the tip of the iceberg when it came time to diagnose her. I went from changing her diet to venison & Pea. To home made food. etc. My cat had diarrhea so loose that she couldn’t make it to the litter pan. I thought it was due to her age but in fact after countless tests and about $3,000 later I figured out that she is much better on a medicine called metronidazole and it works wonders for her. She is on a much more affordable cat food along with this medication. Just a friendly tip from someone who has gone literally through the ringer trying to figure out this problem 🙂 The medicine is super cheap a month too!!

    • Metronidazole is an antibiotic that also has anti-inflammatory properties, which is why it works well for some cats with chronic intestinal issues. I’m glad it’s working for your cat, Jennifer.

  10. Allergy tests are also available. One test revealed an allergy to eggs with one cat. Another test revealed an allergy to chicken and beef for the other cat.

  11. For my cat and dog hypoallergenic, elimination and novel protein diets failed to identify all their allergies so both continued to be sick. Subsequently, my veterinarian sent blood samples to the lab for diagnostic testing for airborne and food allergies. Both my dog and cat tested positive for both types of allergies. By conducting a thorough evaluation for several types of food and non-food allergies, I know the exact allergens for each. Their allergies are much more manageable now. Air purifiers, use of sites that map allergen levels in various areas and home environment adjustments in combination with dog food and cat food absent the protein and non-protein foods to which each one is allergic keep my dog and cat out of misery and related illness such as GI upset or infections.

  12. My cat was diagnosed of Eosiniphilic Granuloma complex, due to hormon imbalance. I had him in hormone therapy. Now I am wondering if this actually works, because he is still licking himself until he is bald in certain area (itchy skin?). He is on Blue Buffalo.

  13. I have a 1 yr old cat that has all kinds of allergies. I had my Vet do a blood panel on him to figure out just what he’s allergic too. Got back 3 pages of items. Chicken, Fish, & eggs were the food items. then there are the various weeds and grasses all of them grow in the area I live in. The head scratcher / funny allergy that came back was that he is allergic to Human Dander yes my cat is allergic to me. From what I’ve read he is .05% of cats that have this kind of allergy. That one is a hard one to treat. I have him on Duck and Pea but I think he has so many allergies that he still itches. I found a oral herbal drops that seem to work for the most part. I first tried the Spirit Essences but it didn’t work with his multi allergies.

  14. My mom had two cats, Pebbles and George. George appeared to be sick for a long time, had diarrhea for a majority of his life and was severely overweight. My step-dad wanted him brought to the SPCA to be euthanized, my sister and my actual dad intervened and took him in. My actual dad feeds his cats a good quality, grain-free diet. After a few weeks on that, George wasn’t sick anymore and over the past two years he’s even dropped a few pounds. c:
    We (And my dad’s vet) think he was allergic to the grain in the food my mom was giving to him and Pebbles.

  15. This post was so interesting. Does sound like a very long process to find out what kind of food allergy. Need lots of patience it sounds like.
    Sue B

  16. there are allergic formula pill pockets for those cats that are on duck novel protein. They are only duck and pea, and have worked very well for me!! You might want to let folks know that they have these as an option as your article states that all pill pockets are not “ok” if you’re on a novel protein diet. Thanks!

    • Thanks, Cindy. I was aware of this “allergy” formula, but they will only be okay for a cat on a novel protein diet is the protein used in the diet is, indeed, duck. They won’t work with other protein sources also used in novel protein diets.

  17. treating food allergies can be BEYOND frustrating!! The vet and I originally thought that Cody has food allergies, now we aren’t so sure.
    I am about to embark on possibly putting him back on mainstream food (along with his coconut oil) and see what happens…..wish me luck!

    • Hello, I was reading the replies to this topic of food allergies in cats and saw your response. I have a Maine Coon cat that is showing signs of itchy skin and hair-pulling. The elimination diet seems daunting to me and I don’t know how I would do it (I have 3 cats). What really caught my eye was your mention of coconut oil. Almost 2 years ago I almost lost the cat I mentioned due to “unknown” causes – he developed an autoimmune response to what we think must have been coconut oil because it was the only new addition to his diet. Have you given your Cody coconut oil for very long? I’m just curious because although I researched the coconut oil for cats before giving it to him and it seemed to be fine, our vet found negative information while researching it after the fact. I also should say that in our research we found that Maine Coons are super-sensitive to certain things that other cats can tolerate. I just felt compelled to share this information.

    • Hello Caren,
      Can you share in more detail your comment about giving
      your cat coconut oil? I have had no luck with my cats “food
      allergy” for over a year now…I don’t know what to do anymore
      He has been on just about every type of food there is and the
      symptoms keep returning.

    • would love to help!

      Hard to get a cat to eat coconut oil but it has omega’ 3’s which is good for skin..
      There are many reasons why they chew themselves to bloody welts, and it may not be a food allergy. Or does your cat have the runs? Source needs to be determined first. before treatment obvioulsy. Is he having typical IBD symptoms or dermatitis and skin issues? Vets are not trained in diet so they use z/d hydrolized chicken which is chicken treated with hydrogen.. Makes no sense to me since it is common allergen.. Truly trained holistic professionals might be useful for you?

      Editor’s note: A link has been removed from this comment.

      • I would recommend working with a holistic veterinarian on diagnostics. Allergies can be hard to diagnose and manage.

        I’m not a proponent of the hydrolyzed protein diets, either, because I don’t like the ingredients, but they actually do make sense. The protein is broken down to the molecular level, which removes the potential to create an allergic reaction.

        • I disagree Ingrid. That is an extremely poor diet. Loaded with soy and corn and common allergens. The potential for allergic response in hydrolyzed protein is still there. Am sure you are aware – many vets advertise as holistic are not at all ? It is a marketing ploy. Having worked alongside for 20+ years i can tell you there is really a very small number who understand diet and those few excel – the rest are prescribing the worst possible diets and putting pets on leukeran which will kill the cat in a few years after the pred no longer works.

          • I’m not saying that the hydrolized diets currently on the market are a good choice as far as ingredients go, Shanti – just that the concept makes sense in terms of addressing allergies.

            I also agree that many vets are not well-versed when it comes to nutrition, and I have a great deal of respect for the vets that do take the time to educate themselves on what they learn about nutrition beyond the courses that are offered in vet schools, which are usually sponsored by major pet food companies.

            Conventional drugs have their place in treatment of some conditions, including allergies, and dismissing them categorically does not serve cats or their guardians.

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