I had relatively minor allergies to Red Cat and Purdy. Perpetually runny nose was the main symptom, but it wasn't bothersome enough to do anything more than to take Purdy, the long-hair, to a groomer every three months. I took Red Cat once, too, but he turned ballistic and the groomer told me never to bring him back. I might try taking him to a different groomer one of these days, though, as I think the groomer I'm now taking Purdy to is probably more experienced and better equiped.
In September I added a third cat, Sheba. That's when my problems really started. She has very short hair, but man, does she put out the allergens! I could tell right away after I got her that whenever she would get near my face, my nose started tickling, I'd occasionally sneeze, and I'd even feel the problem in my lungs. Not a serious breathing problem, but enough that I knew she was affecting me. Thankfully, I've adjusted enough to her now that I no longer have the breathing problem. My eyelids have been swollen and sore ever since I got her, though. Unfortunately, I also have a problem with my eyelids (the oil glands block up), so I really didn't know how much of my problem was due to Sheba and how much to my blepheritis. I took Sheba to the groomer December 31, but I also started antibiotics for my eyelid problem about the same time. My eyelids show definite improvement, but I still don't know how much of the problem was from the cat. I expect that as the month goes on, if the problem starts getting worse again, I'll know it is time to take Sheba back to the groomer.
I'm not the only one with allergies to Sheba, though. My stepdaughter is allergic to cats. Every time she came before when I just had the two boys, as long as she took a Claritin, her allergy was noticeable but tolerable. But she came on Christmas Eve for the first time since I got Sheba. Her allergy got so bad that she just ate and left, though she had planned to stay overnight. She said she even had to stop her car for a time on the way home because one eye was swollen shut and the other was running so bad she couldn't see. She had taken an allergy pill before she came, too, but it wasn't enough to cut it.
I have a portable air cleaner that I have started to use, and that seems to help me some, too. I may need to get another, so I'll have one for upstairs and one for down.