Well, my guys never got into tissues, thank goodness, but I have heard of lots of kittens doing it. I don't think it will harm the kitty, but if you want to stop it, I think you'll need to keep the tissues out of her reach. Maybe behind a closet door or covered with something - and of course, if all else fails, then get out the water gun and every time she goes for the tissues, squirt her. I guess she is having so much fun that she can't contain herself! It does sound like fun. I have heard of children shredding papers/magazine/tissues....too! IT MUST BE FUN. I bet she out grows it before you out grow your allergies!

Keep us posted!

P. S. I had a cat that loved my makeup kits and would roll around in/on them every chance she got. It took me awhile to figure out why she had such a pink/red chin. Here she was rubbing her chin in the blush and lip gloss. She would also lick my neck if I had on perfume. She just loved my perfume so! The Vet used to get a kick out of watching her lick my neck.