Hair disorders manifest as either hair loss or excessive hair growth. Hair loss may involve excessive shedding or baldness, presenting as localized or diffuse patterns, with or without scarring. Increased hair can result from hormonal factors (hirsutism) or non-hormonal causes (hypertrichosis).
Hair Growth Cycle
Hair develops from follicles beneath the scalp and progresses through four stages: anagen (growing stage, 80–90% of hairs, lasting 2–6 years for scalp hair), catagen (regression stage), telogen (resting stage, 10–15%, approximately 3 months), and exogen (new hair phase where old hair sheds 50–150 daily). Hair grows approximately 1.25 cm per month.
Diffuse Alopecia (Hair Loss)
Androgenetic alopecia represents the most prevalent hair loss form, occurring in both genders as male-pattern or female-pattern baldness. In men, loss begins above temples and progresses to the crown; in women, thinning occurs across the head.
Telogen effluvium marks the second most common hair loss type, characterized by significant scalp hair decrease. It typically follows childbirth, sudden weight loss, blood loss, fever, or stress by two to three months.
Diffuse alopecia stems from infections, nutritional deficiencies, hormonal imbalances, physical or emotional stress, alopecia areata, or medications.
Localized Alopecia
Alopecia areata represents the most common localized baldness cause, affecting the scalp and other hair-bearing areas. As an autoimmune condition, it occurs more frequently in individuals with autoimmune disease history or family predisposition, typically beginning in childhood or young adulthood.
Inflammatory Hair Loss
These disorders may produce scarring (cicatricial alopecia) with shiny, pale skin and reduced or absent follicular openings.
Lichen planopilaris is a rare inflammatory condition causing permanent scalp hair loss, primarily affecting young adult women, though men may develop it. Its cause remains unknown.
Frontal fibrosing alopecia typically affects women over 50, causing even hair loss on the front and sides of the scalp alongside eyebrow loss. Affected skin usually appears normal but may be pale, shiny, or mildly scarred.
Folliculitis decalvans affects hair across the body, producing round or oval hair loss patches with pustules surrounding follicles. As hair sheds, follicles are destroyed and scarring results. It impacts both genders beginning in adolescence or adulthood.
Dissecting cellulitis is very rare, with scalp pustules developing and permanent hair loss resulting. Untreated infections, including fungal infections, can cause permanent hair loss.
Consult a dermatologist if you suspect any mentioned hair disorder.