My Auntie has used it for years and never mentioned about it staining her teeth.Although maybe she never knew! However, my girlfriend's sister (who is a dental hygienist) said that it does indeed stain. I used it recently, but only for 2 weeks - as per my girlfriend's sister's advice.
Marrkarnell mentioned that staining can be reduced by avoiding tea, coffee and wine. However, that - to me - states the obvious. Everyone knows that tea, coffee and wine staines the teeth!
Corsodyl should only be used to treat gum problems and not as a regular mouth wash. If symptoms persist for longer than two weeks then you should go see your dentist anyway!