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Cat pulling hair on new diet. How long till hypoallergenic food works?

Updated On September 23rd, 2025

Pet's info: Cat | Mixed Breed | Male | neutered | 8 years and 7 months old

Hello. My cat has been pulling his hair off for a long time. He is a house cat, so he does not go outside and hasn't caught any external parasite. Due to this issue, we have changed his diet to Purina's PRO PLAN® VETERINARY DIETS HA HYPOALLERGENIC Feline. He has been eating it for 2 weeks but it does not seem to be working. We are desperate for a solution. Thank you for your time.

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1 Answer

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Answered By Dr. Elizabeth

Veterinarian

Published on December 6th, 2019

That is good that you are looking into food allergy. It is important to rule out all causes of allergies. You should not expect to see any changes in his behavior for AT LEAST 4 weeks minimum. A food trial is a full 16 week event and you will not know the full effects until then. Make sure you are conducting a proper food trial and keep your veterinarian updated. Don't stop the diet without talking with your vet. If Jorge seems uncomfortable, your vet can provide medications to make him feel better. I hope this helps.

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