Hair Loss (Alopecia)
Androgenetic alopecia and alopecia areata are the two most common forms of hair loss, managed per AAFP guidance and a European expert consensus statement.
Symptoms
Androgenetic alopecia causes gradual thinning in a patterned distribution (crown and temples in men, diffuse crown thinning in women); alopecia areata causes sudden, well-defined round patches of hair loss.
Causes and risk
Androgenetic alopecia is driven by genetics and androgen sensitivity of hair follicles; alopecia areata is autoimmune, with the immune system attacking hair follicles, often alongside other autoimmune conditions.
How it is evaluated
Diagnosis is largely clinical based on the pattern of loss; targeted (not routine) labs and sometimes a scalp biopsy help when the picture is unclear or another cause is suspected.
Treatment
For androgenetic alopecia, topical or low-dose oral minoxidil is first-line for both sexes, and finasteride is FDA-approved first-line for men. For severe alopecia areata, oral JAK inhibitors (baricitinib, ritlecitinib, deuruxolitinib) are FDA-approved and positioned as first-line systemic therapy per EADV consensus, though response takes 6-12 months and relapse after stopping is common.
When to seek care
Sudden, patchy hair loss with scarring, redness, or scaling of the scalp should be evaluated promptly, as should any hair loss accompanied by other new symptoms -- these can signal a scarring alopecia or an underlying medical condition.