Shampoo cannot help keep or regrow hair.
I can recommend an excellent physician who I go to who is a top doctor in the US for just this issue. I bh have seen fantastic results. I started going to him as a preventative measure. My hair started getting thinner and I got nervous. H-shm decided that I should have this issue and I will go to this physician and follow his instructions until this no longer is an issue or iyh until I get married. (If I want my hair to look a little fuller when I go out, I wear one or two layers of clip in extensions from ben simon. Sew in/glue in extentions can cause further hair loss.)
He is expensive but I look at this as a health issue. It is just a fact in the US that women need their hair. Your friend should not feel like she is vain for wanting to do something about this issue. She will be doing what she is meant to do in this situation. Tell your friend that I recommend that she doesn’t wait because it is easier to keep the hair you have with medication than to regrow hair which may require surgery. My doctor told me about a recent development with laser therapy that regrows hair as well.
His name is Doctor Michael Lorin Reed and his number is (212) 888-2260. He has a website and a book about women’s hair loss and you or your friend can google him.
He is a fantastic shaliach and I couldn’t be happier.