Glucosamine Allergy in Cats

Glucosamine Allergy in Cats - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost

What is Glucosamine Allergy?

Food allergies are becoming increasingly common in our pets.  They present a stressful situation for the pet and owners alike. The constant scratching keeps owners up at night, the repeated veterinarian visits gets costly, and it seems to be never ending.  While tedious, if you are able to diagnose the cause of your cat’s food allergy, you can then remove it from his diet and he should recover very nicely.  If your cat has a glucosamine allergy, it should be fairly easy to remove it from his diet and put him on the road to recovery and healing.

Glucosamine is a supplement many older pets receive to promote healthy joints and bones.  If your cat takes this supplement but is also experiencing any of the symptoms listed below, consult with your veterinarian.

Symptoms of Glucosamine Allergy in Cats

  • Alopecia 
  • Pruritus
  • Erythema
  • Papules
  • Dermatitis
  • Weight loss
  • Abdominal pain
  • Flatulence
  • Diarrhea
  • Vomiting 
  • Inflammatory bowel disease


There are three different types of glucosamine available for cats: glucosamine sulphate, glucosamine hydrochloride, and N-acetyl glucosamine. Glucosamine supplements available for cats typically include one, multiple or all of these types.  Most owners start their cat on glucosamine supplements as they age to support healthy bone and joint health.

Causes of Glucosamine Allergy in Cats

While glucosamine is a supplement and not a food per say, it is still considered a ‘food allergy’ since he ingests it.  A food allergy is caused by a hypersensitivity reaction to a food ingredient or additive.  It is uncommon to hear of a glucosamine allergy, but it is not impossible.  If your cat is allergic to glucosamine or something within the glucosamine-containing item, it is his immune system responding to threat to his body that isn’t there.  Your cat’s body responds in an attempt to protect itself by breaking out most commonly with skin discrepancies and gastrointestinal upset.

Diagnosis of Glucosamine Allergy in Cats

The clinical visit will begin with a physical examination of your cat. His symptoms will be indicative of a food allergy which will lead the veterinarian to begin questioning you about your cat’s diet.    She will want to know when his symptoms started, if they have been progressing, if you have been trying to treat at home with over the counter products and so on.  All these details can help the veterinarian with her diagnosis.

It will be important to rule out other possible causes of your feline’s symptoms such as a parasitic skin infection or gastrointestinal disease. These conditions can cause similar symptoms in your cat and will require some basic diagnostic testing to rule them out.  If you want to evaluate the possibility of environmental allergies, there is a blood serum test available. 

Presently, there is no serum, blood, or intradermal test reliable for diagnosing food allergies.  The main way to come to a proper diagnosis is a trial and error dietary study.  You will need to remove glucosamine from your cat’s diet for a minimum of 12 weeks.  This gives his system time to rid itself of glucosamine and symptoms will begin to resolve.  Gastrointestinal issues may resolve as soon as 1 to 3 weeks but dermatologic symptoms take much longer.  If your cat’s symptoms have resolved during this time, you need to reintroduce glucosamine to his diet to get a confirmation.  If his symptoms reappear once your reintroduce glucosamine, this is the suspected allergen.

Treatment of Glucosamine Allergy in Cats

There is no specific or exact treatment for a food allergy.  Instead, the veterinarian can offer supportive treatments and therapies in response to the symptoms your cat is suffering.  His symptoms will determine his course of treatment as each cat experiences their symptoms differently from the next.  

If he is experiencing any gastrointestinal upset from the glucosamine, your veterinarian can offer medications and therapies for it as well. There are medications to calm the GI tract she can administer to your cat in the clinic and send you home with some as well.  

For skin related symptoms, she will offer medications as needed.  For inflammation and itching, she will likely offer antihistamines or a steroid to calm his skin and offer him relief.  If he has developed a secondary skin infection, she can prescribe the needed antibiotics.

If the veterinarian is able to confirm the source of the allergy is the glucosamine you are supplementing him with, you can remove it from his diet and prevent symptoms from continuing and even worsening.  Without removing the source of your cat’s allergy, your cat will continue to suffer from the allergy since you will only be treating his symptoms, not the cause.

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Recovery of Glucosamine Allergy in Cats

Continued avoidance of glucosamine from the diagnosis forward is essential. The ingredients of all supplements, foods, and medications will need to be checked for the offending allergen, in this case glucosamine, before giving to your cat in order to avoid a relapse of symptoms in the future. If you have any doubt about a food, supplement, or treat item consult your veterinarian.

Glucosamine Allergy Questions and Advice from Veterinary Professionals






15 Years


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My pet has the following symptoms:
Loss Of Appetite
Loss Of Appetite, Lethargic
Loss Of Appetite, Bloating
My 15 year old female tabby cat has arthritis. I tried Cosequin chewable but after about 2 weeks of a daily dose she lost her appetite and became bloated and lethargic. Following a trip to the vet and an xray the diagnosis was constipation. The vet was able to relieve her and sent her home with a stool softner. Although the vet stated it was rare for Cosequin to cause constipation in cats, I decided to stop the chewable in her daily routine. Following about 10 days of regularity with the stool softner, I decided to try liquid Glucosamine Chondroitin MSM for cats. After 1 week she had loss of appetite, bloated and lethargic. I decided to remove this from her daily routine again. After 3 days (with the stool softner) she is eating, no longer bloated and eating. The downside is she is in PAIN. Not sure what to do now to reduce her arthritis pain and not have her experience side effects.

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