I read this short story only a few years ago. I remember it was in a SF collection but I don't remember anything about the other stories. So it might be very old. But it does not have the "taste" of an old classic. It was in english, of that I am sure.
It is about a young girl who thinks she is ugly. There is no evidence about whether it is true or not. She is in a hospital, where she repeatedly manages to get hold of a specific poison, despite the efforts of the doctors and the nurses, who had managed to save her many times before the episode told in this story. The reason she wants to kill herself with this particular drug is because she believes that it will cause her corpse to be beautiful. Again, there is no indication whether this is true or not. The story consists in her thoughts during her current attempt to kill herself. I don't remember whether she does succeed this time or whether they save her once more. (Till the next attempt, surely !)
One detail that I remember : she calls a "suicide" any person like her, who keeps attempting to commit suicide. "One should never do (or tell) such or such thing to a suicide" is a recurring sentence.Strange how a small detail like that remains in my memory when I forgot most of the story...
There was some SF context in the story (beyond this particular drug), but I don't remember what it was. I found this story rather disturbing, really...
