hairball prevention

Im feeding my cat the royal anti hairball dry food. Does anyone know if it really works ?

I have no experience with it. I assume it is a high-fiber food? It makes your cat's stool bulkier than it was? Cat stool is normally pretty small, firm, and a bit dry. Long term, the bulky stool can impact muscle tone. Megacolon is a potential problem as a result of the unnaturally large stool. If you want to use this short term, there likely will be no problem. I hope it helps. But you may want to consider this

http://consciouscat.net/2010/04/28/some-startling-new-thoughts-on-cats-and-hairballs/

And the information I posted here: http://www.thecatsite.com/t/299988/what-do-you-do-for-hairballs#post_3765394