Non-scarring hair loss is much more common in women and is caused by:
- alopecia areata, characterized by round patches of hair loss on the scalp
- tinea capitis, a fungal infection
- female pattern hair loss, which is characterized by classic patterns of hair loss
- medical causes
Common medications that can contribute to hair loss are cholesterol-lowering drugs, anticoagulants, antacids such as ranitidine (Zantac) and famotidine, medication for gout, anti-arthritics (naproxen) and vitamin-A derived drugs such as Accutane. Hair loss can also be cause by trauma to the scalp from radiation, surgery, chemical burns or traction (wearing of tight, pulling hairstyles over time).
Female pattern hair loss is the most common cause of hair loss in women. Incidence is difficult to determine but has been estimated to be as high as 50 percent of women by menopause. Its onset is subtle and there are variable patterns of loss but hairline is usually preserved. The age of onset is highly variable but there are usually two main peaks: women who lose in their 20s and 30s and women who lose their hair in perimenopause during their 50s and 60s.
Androgens, hormones that promote masculine characteristics and which play a significant role in male pattern baldness, are also implicated in female patter hair loss but it is less clear how.