My Mom was what I called a selective hypochondriac. Whatever us girls got Momma got only much worse. We were terrified to tell her if we had something wrong because we knew she would make herself sicker than we were. We changed the subject or lied when she asked how we were and we NEVER asked her how she was unless it was obvious there was something wrong. She lived on the sympathy and attention we gave her if she wasn't feeling well. When we realized we were enabling her we had to learn different ways to talk about things or just not talk about health at all. My older sister is now a hypochondriac and her husband enables her. I love her to death but will not talk health with her unless it is absolutely necessary. Like Leed said, change the subject or just refuse to talk about it. It's hard but you will end up feeling responsible for the other person's choices if you don't avoid the conversations that set them off. Good Luck!