My daughter constantly pulls her nails and toenails

Hello doctor: My daughter is 13 years old and several months ago I noticed that she was tearing and pulling both nails and toenails. The nails were not even enough long to be clipped and we talked about it and I asked her to stop doing it because she was hurting herself. (The toenails specially looked  extremely short )
She agreed. I checked on her couple of day later and she improved a little and showed me the improvement and then start doing it again in couple of days. Seems that she can't stop doing that. I remember that she used to like to go manicures and pedicures and I even rewarded her when she improved sometime ago, but now seems that she doesn't even care and I keep asking her to stop touching her nails and she gets upset and she tells me "I know mom! I will let them grow! What can I do for her.?

[Roger Gould, M.D.]

This sounds like a compulsion, and compulsions are usually treated by psychiatrists, and often times with medication. You should get a consultation with a psychiatrist.