We have four cats, two of them usually stay indoors. The remaining two, we like to keep outdoors. If you are allergic to your cats and they are constantly indoors. First of all,keep them in the basement or a separate room, particularly when your cats start shedding. In addition keep them brushed regularly when they begin to shed. Also a good air filtration unit which can be purchased at a home depot for example, cuts down the amount of cat dander floating around in the air. The placement of a good quality furnace filter, depending on the heating and cooling system in your home will also help. Make sure you purchase a filter that removes animal dander and pollen for example. And if you haven't already,you may want to consult an allergist and get evaluated to see if you are highly allergic to cats. If you are and want to keep your pet cats indoors, may have to resort to monthly allergy shots. Hope this advice helps.