I'm so sorry to hear about your daughters problems, I can only imagine how you feel. I am a mum and a grandmum myself, I know how I would feel. *hugs*
I'm also a self harmer. I used to be a 'cutter'. I haven't cut for a number of years but I still get the urge to do so particularly when I am stressed. I can't answer questions on medication, I don't use any now because of adverse reactions in the past. I can help with the issue of self harm though.
There are many reasons why we hurt ourselves. Mine for a variety of reasons, I was abused as a child, I was taught that I was 'worthless, ugly and useless'. :-( I also cut in response to an overload of stress, usuallly emotional stress.
Have you been able to talk to your daughter? has she said anything at all as to why she cuts? Has she had problems at school, being bullied etc? has there been a recent upheaval in your lives? Divorce, bereavement, anything like that?
It is going to be difficult, living with a self harmer, but she can recover from it, she WILL recover from it, but it will take time, maybe quite a long time. You must be prepared for that. I describe myself as they do in AA or GA, I'm not cured of my self harming, I'm a 'recovering' self harmer, I'm only one cut away from doing it again.
She is going to need all your love and support, no matter what she does to herself, you must tell her you love her, don't ever let you see that you're disgusted with her, that will only reinforce the feelings that she has. because she will be so confused, angry and disgusted with herself.
Some people self harmm because they feel worthless etc, others do it to punish themselves.
Self harming can also be a 'coping mechanism'. A way to feel 'in control' of some area of their lives.
My own personal experience of it, when I got too stressed and the pressure built up inside, cutting 'relieved' that pressure, much in the old ways of 'blood letting'. When the blood flowed, the pressure inside of me eased.
Others do it to provide a 'distracting' pain, they feel such emotional pain inside for whatever reason that they need to create a 'real' pain to distract themselves.
I'll be happy to answer any questions anyone has about self harming, which by the way also includes, Anorexia, Bulimia, drug abuse, alcoholism, etc. I