Alopecia (Hair Loss)

Key points

• • Alopecia is loss of hair, and it is divided into non-scarring, where the follicle survives and hair can regrow, and scarring, where it is destroyed.
• • Male- and female-pattern hair loss is the commonest type, driven by genes and hormones, thinning the crown and hairline.
• • Alopecia areata is a patchy, non-scarring loss thought to be autoimmune, with smooth bald patches and exclamation-mark hairs.
• • Diffuse shedding (telogen effluvium) can follow illness, childbirth, stress or crash dieting, and usually recovers.
• • Scarring alopecia, from conditions such as lichen planus or lupus, destroys the follicle and causes permanent loss.