iMessages Storage Bug still in iOS 8?

Hello, I used the search function but haven't been able to find anything. Since (I think) iOS 7, my iMessages has been ballooning in size (currently at 5.1 GB), despite clearing all current messages. I really don't want to set up my phone as a new phone and lose everything on it, does anyone know of a way to clear out the iMessages?

I see in iOS 8 there's an option to delete messages older than 30 days, I turned this on, but it didn't change anything, I was still able to read messages from early July. Perhaps it will clear out messages 30 days from now? ha.

Any info would be appreciated!

 

Excellent, thank you, that seems to be doing the trick, just quickly cleared out 1GB of photos.