FIRST of all, I think that your friend should see a doctor, or consultant,
and see as to why she is getting hair loss, because their are different ways
to treating different hair loss problems.
I agree, sudden and dramatic hair loss has dangerous causes and they need to be treated quickly or they cause problems in long term.
Sometimes if we just shed a little, it could be due to shampoo change or level of stress but if it's on going and she really has lost a lot of her hair, then it's high time she should visit a doctor.