What causes hair loss in a thirty four yr old woman?

Several things: Could be an infection in the skin losing hair. Could be coming out because of constant pulling as from habit or tight braids. There are immune conditions and vitamin deficiencies that cause hair loss. It is also possible for a woman to be genetically predisposed to thinning hair.

Stress,hormonal,meds: Condition called telogen effuvium, this can lead to hair roots to be pushed prematurely that causes hair to fall out in large amount, this may be due to an illness, major life stress, medications, pregnancy and crash diets.But hair usually grows back when cause is corrected other common causes are 1 thyroid disorder 2 hormonal imbalances and iron deficiency 3meds like antidepressant 4 fungal infectio.