What should I do with a friend who can't keep her mouth shut?

There are some people who are like that, and all the talking doesn't change them. I have a neighbor who I love dearly who is very frank and doesn't care when she speaks out. It is just a part of her personality. You can try talking to your friend and gently explaining that some of the things that she says isn't exactly timed right and that she does need to take a moment to think about if what she has to say will hurt the other person's feelings. That there have been many times that she has even hurt your feelings. Maybe to help her out, suggest that you have a signal that you can give to her that will let her know that her timing is bad and she needs to be quiet and think before she speaks. You're right in being concerned, as part of growing is leaning tact and acquiring the knowledge of when not to speak and when to speak. Maybe, she is hurting others before they have the chance to hurt her. There are many people that have had painful backgrounds and learned quickly that the only way to keep from being hurt is to hurt the other person first. This is a difficult situation, but I would talk to her and try to get her to open up about her past, maybe it is the case that she wants to get the first hurt in... otherwise explain to her that her frankness does tend to hurt people, including you, and that she needs to measure her words before she lets them flow from her mouth.

be frank to her too tell her "your so noisy that annoyed me , so why don't you find someone to talk to if you don't keep quite"....best is to ignore...if people been ignored they stop...!!!

just be straight up with her, ive learn when you are honest it people sometime they like that, other time she might get upset but youre being honest to her

if she dose not listen to your advice i think that having a friend like this is a painful thing for you.why not try to find a new friend instead of her.

if she's your real friend i think you should tell her at once.sometimes people don't tend to change not unless someone tell her. because people like that are less educated in terms of good manners and right conduct, some people tend to be confident enough to utter words not thinking for the complications. need to be told about the Dos and Donts

do not respond her word to much, keep silent, you should respond her with body language, base in my experience, some one like that will be silent after i do that

have you ever heard the saying feed them from a long handled spoon. It means if she is a problem limit contact with her.