I have fairly seerve animal allergies and I am able to build up some tolerance to my own animal's dander while other people's animals cause a reaction. The difference also is that your cats dont stay in the house full time. Your friend's home is covered in dander from top to bottom and that is what makes you have an allergic reation there. Some people are more allergic to animal dander than to the fur itself, which is my problem. Dander is made up of dead skin cells that have been shed and old saliva that the animal used to clean itself with. That dander is built up in your friend's house and covers the couches, chairs, rugs, etc. Any movement stirs this dander up into the air and into your nose and lungs and causes the reaction. My animal allergy is very seerve with dogs but not so much with cats. If I go to someone's house that owns a dog, even if the dog is put away I will starts sneezing and wheezing; especially if there are children around running and making the latent dander fly around. I find that although poodles are supposed to be nonallergenic, that they effect me the worse because they have that beard by their mouth that stays wet with drool and I am allergic to that not the fur, which they say is really hair on a poodle.I had 2 cats in my home and just stayed on Zyrtec or Allegra and that was enough to keep my allergies to the cats in check but when I went to my mother's house with 4 cats I would get all sniffled up despite the allergy pills, probably due to the different properties in each cat's dander that I wasnt used to. Nope it isnt that I didnt want to spend time with my parents or was using the allergy as an excuse to cut out early the reaction was quite real. It was also misunderstood because it was hard for others to imagine how I could have cats in my own house but my nose would turn into a virtual faucett at my parent's house. It just depends on if you are allergic to the fur versus the dander I guess.