What Causes Difficulty In Breathing With Pleural Effusions?

In early Spring, I had a very hard, dry cough which did not respond to antibiotics. Had every test and scan to eliminate everything, which they did. XRay showed pleural effusions. This has been drained twice but came back. All testing shows fluid to be benign. Doctor changed a prescription I have been taking for years to see if I might have developed an allergy to it. Next XRay is to be 8-18-11. I know the fluid is still there but is not causing trouble. When I am lieing down at night and take a deep breath, it is a little uncomfortable, but not bad, and I am not bothered too much in the day. I am 63 and do not want to have surgery. Hope it won t be necessary. Is it dangerous to live with this condition? Thank you.