lol.
I have read some of the replies here and I can't think of a worst thing that attributing hair loss to Hijab.
Your friend needs to a see a doctor ASAP-- for several reasons which I am going to list.
You say she is thinning on top which sounds to me like male pattern hair loss (usually due to androgenic) causes... she needs to have a hormone panel checked, since hair loss with one of these problems would be the least of her worries.
One of the first things that come to mind is polycystic ovary disease.
There is also pre-mature ovarian failure, there is Telogen effluvium: when all hair follicales go into arrest at the same time, but in fact they grow back again in this particular condition. I don't believe that is what she has
Trichotillomania, a term used to describe people who are in the habit of pulling and twisting their own hair.
other Hormone problems. like hypothyroidism or problems with nutrition also can result in unhealthy hair that falls out or breaks easily.
there are also other forms of hair loss called Alopecia Areata, hair loss in small patches, Alopecia Totalis: more than 50% hair loss on the scalp. and alopecia universalis which is all hair is gone... every where...
there is also hair loss that is caused by a type of fungus and the longer she waits chances are hair will never grow back... There are many other causes which I haven't mentioned here because I am in a hurry however, if you want to give your friend excellent advise, you won't find it in cyber section but take her by the hand to the doctor's office, it is best to treat the underlying cause of the problem than speculating on what caused it...
waslaam
alopecia doesn't cause hair thinning, the hair thins at the top of the head due to hormone imbalance.