I have started epson salt baths once a night, and i sit in it for 20minutes. The first time, it honestly kind of annoyed me, I got sweaty sitting in it that long, and I just wanted to get out, but my mom insisted I stick it out. She read somewhere that it is recommended you sit in 3 times a day for atleast 21 minutes. I don't have that much time!!!!! But I do make myself sit in it once a day for 20 minutes. It relaxes me. I think it helps with the pain while I am in there and maybe a little while after until my body loses the warm feeling.

I would say it is worth a try for your daughter!