Thank you for the question.
There many causes of hair loss in teenagers, and it is difficult to tell you what your daughter has without seeing and examining her.
One of the commonest cause of hair loss is telogen effluvium. This is hairfall following a stressful episode such as high fever, crash diets, emotional stress etc.
The hair will fall usually starts about 2 months after the stressful event, and may persist for 2 to 4 months. However, the hair that is lost will gradually regrow.
Blood tests to rule out underlying medical conditions such as thyroid disease or iron deficiency and autoimmune conditions may need to done in some cases.
There are many other causes of hair loss too like alopecia areata, trichotillomania, female pattern hair loss etc.
I would suggest you bring your daughter to see a dermatologist/doctor for a proper assess and management of her hair loss.
