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What is Iams Allergy?

Iams is a brand name for a variety of cat foods that are made by Spectrum Brands and Mars, Inc. Iams sells food that has been designed by nutritionists and veterinarians for cats and dogs in the following formulas: ProActive Health, Healthy Naturals and Premium Protection. There are also special veterinary formulas available for animals with special dietary needs. 

An allergy will occur when a cat’s immune system responds excessively to one or more of the food’s ingredients. When this happens, your cat’s skin will become itchy and inflamed and he can develop chronic ailments like ear infections and wheezing.

An allergy to a particular food occurs as a result of an overreaction of the cat’s immune system to one or more of the proteins that are present in the food that has been consumed.

Symptoms of Iams Allergy in Cats

Should your cat experience an allergy to a particular food, you may notice skin reactions, often under his front legs, around his face and groin area, as well as between his toes. Symptoms include:

  • Hair loss in patches
  • Rubbing his face
  • Shaking his head
  • Hives
  • Excessive licking
  • Paw biting
  • Skin rashes and infections

Other symptoms can include:

  • Coughing
  • Wheezing
  • Diarrhea
  • Chronic gas

Rarely, an allergy to a food can cause anaphylactic shock, which is life threatening and requires immediate medical attention. Symptoms of anaphylactic shock include:

  • Cold limbs
  • Breathing difficulty
  • Increased heart rate
  • Pale gums
  • Seizures
  • Sudden diarrhea or vomiting


Iams offers a variety of wet and dry cat foods to include:

  • Proactive health
  • Naturals
  • Veterinary formula
  • Purrfect Delicacies
  • Purrfect Delights
  • Purrfect Grain Free

Causes of Iams Allergy in Cats

The majority of your cat’s immune system cells exist in his gastrointestinal system. An allergy to a particular food is activated when your cat’s immune system overreacts to a protein that has been ingested. 

When your cat digests his food, his system will usually break down the foods he has consumed into amino acids, which enterocytes will absorb and transport into his bloodstream. If the proteins he has consumed are not broken down as they should be during the digestive process, the enterocytes look at them as “intruders” and launch an attack on the proteins.

Diagnosis of Iams Allergy in Cats

Should you notice concerning symptoms in your cat, you will want to bring him to your veterinarian. In addition to conducting a physical examination, your veterinarian will ask you for information regarding the symptoms you have observed, when you first noticed them and whether there have been any changes. He will also ask you about any changes in your cat’s behavior, as well as for information regarding his diet, supplements he is taking, and any recent changes.

As your veterinarian will see the issues with your cat’s skin that he is experiencing, he will likely collect samples of the skin cells from any affected areas. These skin cells will be studied under a microscope (called cutaneous cytology) in order to see if mites, yeast infections or other diseases are causing your cat’s symptoms. Should these not be present, your veterinarian will likely consider a food allergy and will recommend an elimination diet, which will help to confirm that there is an allergy and determine what is the cause. Often, an elimination diet will involve changing what your cat eats to bland food made at home or a hypoallergenic commercial product. Your veterinarian can help you choose foods that are not eaten currently by your cat. In the case of a food allergy, within a few weeks on the new diet, your cat’s symptoms will disappear. You can then add individual ingredients back into his diet until you are able to determine which one he is reacting to.

Treatment of Iams Allergy in Cats

While you cannot cure an allergy to a food, your cat’s symptoms should resolve themselves once the food is eliminated from his diet. While you are administering the elimination diet, your cat may still be experiencing some ongoing symptoms of his allergy that can be treated with corticosteroids, which will minimize swelling and antihistamines, which will help with the itching. You and your veterinarian may choose to not minimize his symptoms during the elimination diet, so that it can be clear what is causing the allergy.

Often, when a cat has a rash from a food allergy, his excessive licking and biting can lead to a secondary bacterial infection. Should this occur, an antibiotic will be prescribed to resolve the infection. 

Once you are clear as to what element or elements are causing the allergy in your cat, you will want to be sure that your cat’s diet does not include that item or items. As animals that develop an allergy to one food may then develop additional allergies, it is important to monitor your cat’s reaction to the food that he consumes.

Recovery of Iams Allergy in Cats

As you work with your veterinarian regarding an elimination diet, you will want to be sure that you avoid any ingredients that are present in your cat’s current food. As the allergy may be to a family of foods as a whole, if your cat is currently eating beef, you should consider switching to a protein aside from red meat. While your cat may be tempted by table scraps or treats, it is important that he eat only the foods on the elimination diet so as to best identify the source of the allergy and avoid a reaction.

Iams Allergy Questions and Advice from Veterinary Professionals

13 Years
Moderate condition
0 found helpful
Moderate condition

Has Symptoms

vomiting, scratching, biting skin

I was feeding my cat Friskies and noticed she was throwing up often. I switched to Cat Chow which helped with that. One day I went to the store and could not find the Cat Chow and bought Friskies again. The vomiting began again. I decided then to try IAMS since I had heard it is supposed to be very healthy. I mixed the foods for a while and then eventually stopped mixing in the Friskies. Now my cat has begun vomiting again periodically and is scratching and biting her skin along with shaking her head and acting like she wants to hide. Random tufts of fur are also being found all over the house.

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American Shorthair
3 Years
Moderate condition
0 found helpful
Moderate condition

Has Symptoms

Licking at Genitals
itchy skin
Butt Discomfort

I am looking for a new food to try for my cats food allergy. He is currently eating Iams healthy adult food. What brand of hypoallergenic food would you recommend trying first?
He is very itchy, has little stools, and irritated butt. He licks his tail and butt. He also randomly jumps up in the air every once and awhile and looks behind him and then licks his butt. He is almost 4 years old.

Dr. Michele King, DVM
Dr. Michele King, DVM
1611 Recommendations
Thank you for your email. Without seeing Simba, it would not be a good idea for me to recommend a food for him. Food allergies are far less common than environmental and flea allergies, or anal gland problems. It would be best to have him examined by a veterinarian, as they can assess his overall condition, determine what might be going on, and recommend any treatment, including a change in food if necessary, that might help him.

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Polly Anna
DSH polydactyl
15 Years
Serious condition
0 found helpful
Serious condition

I recently changed litter from corn to clay to get a new cat to use the box. One of my resident cats has suddenly begun licking her front paws and then washing her face and the paws and face are deep brown, almost black. She is almost feral and cannot be caught to get to our vet. I have no idea what is going on or how to treat her but my husband came up with the litter idea. She is a precious 15 year old who has lived with us since her birth. I brought mom and 4 babies home from a bush in which they were born the day of their birth. She has never socialized. Her brothers were wonderful. She also has started drooling but her mouth looks good (when I can see into it for 2 seconds when she cries.) I have predisone from her brother and I can get benedryl. She also stopped grooming herself and is terribly matted on her hips. I've been months trying to get her into the vet. Any help would be appreciated. I'm typing this because I cannot sleep or handle this anymore. I love her so much and cannot help her. Thank you.

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3320 Recommendations
I cannot recommend that you use prednisone on her since I haven’t examined her and the prednisone wasn’t prescribed to her; cetirizine at 5mg per day is more suitable for a cat than Benadryl which is more suitable for dogs. Without examining her I cannot give you much guidance and cannot tell you anything to do if you cannot catch her; speak with a charity organisation near to you as they may have a humane trap to catch her so that she can be taken into your Veterinarian. Regards Dr Callum Turner DVM

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