You can try the over the counter stuff first, Benadryl, Clariten etc, if you are lucky they will work for you.
Also keep your house VERY clean, and well ventilated to help prevent build up of allergens in your home.
Vaccum your carpets and furniture weekly, dust frequently, and where a mask while dusting. Scoop / change litter boxes outside only, and when you need to clean them with water, clean them only with cold water instead of hot water.
Do grooming outside while of course holding your cat so they can't get away, so that all that fur just doesn't start floating around your house inside from combing indoors.
That's just a few simple tips
