Your sister seems to be suffering from a type of diffuse hair fall
known as telogen effluvium
. This hair fall usually occurs after a period of prolonged fever
or illness as in dengue
. This kind of hair fall is self limiting and usually resolves spontaneously in six months time with most of the hair growing back.
The treatment given by the doctor is apt for this kind of hair fall. She should continue with the treatment for 3 to 4 months to be satisfied with results. Also ask her to improve her diet. She should take a balanced nutritious diet rich in proteins
Hope that answers your query.