Found a home.
It sounds like a very difficult decision, and I understand you want the best for Fluffy. Here is a simple, caring notice you can use for rehoming:
Due to unforeseen circumstances, I urgently need to rehome my beloved cat, Fluffy. This is through no fault of his own, but sadly, I have developed a severe allergy, and medication is no longer effective.
Fluffy is a wonderful companion who deserves a loving forever home. (Please insert details here, such as: He is a 2-year-old male, desexed, and very affectionate. He is fully litter trained and enjoys quiet cuddles.)
I am seeking a caring individual or family who can provide him with a safe, loving environment. Serious inquiries only, please.
Dogs have access to: warm bedding, water at all times, ample space to exercise, natural light
Dogs have enrichment provisions: Yes
Dogs are exposed to: people with different appearances or ages, different sounds, I use a formal socialisation program (e.g. DoGoodDoggy)
Offers lifetime rehoming: Yes