Androgenetic alopecia
By The Treatment Registry editors
Hereditary pattern hair loss in men and women, driven by androgen sensitivity in genetically predisposed follicles. Treatment combines medical therapy to slow progression with surgical hair restoration to redistribute donor follicles. Surgical results are best in patients with stabilised pattern loss and adequate donor density; the underlying genetic process continues so combined medical-surgical management is often appropriate.
Clinical overview
Signs and symptoms
Pattern hair loss is a form of non-scarring hair loss. Male-pattern hair loss begins above the temples and at the vertex of the scalp; as it progresses a rim of hair at the sides and rear of the head remains, referred to as a Hippocratic wreath, and it rarely progresses to complete baldness. In most cases a receding hairline is the first starting point, moving backwards from the front and sides of the head. Female-pattern hair loss more often causes diffuse thinning of the hair across the scalp without hairline recession and similarly rarely leads to total hair loss; the frontal hairline is typically preserved while density decreases in all areas. Severity is graded in women using the Ludwig scale.
Causes and risk factors
The cause is not fully understood but appears to result from genetic changes that make scalp hair follicles sensitive to androgenic hormones, with dihydrotestosterone (DHT) the major contributor at the dermal papillae; 5-alpha-reductase converts free testosterone into DHT and is highest in the scalp and prostate gland. Men with androgenic alopecia typically have higher 5-alpha-reductase and higher total, free and unbound testosterone and DHT. Inheritance is generally regarded as autosomal dominant, although roughly 80% of bald men have bald fathers, suggesting an important paternal route. Oxidative stress, the scalp microbiome and insulin-like growth factor activity at the dermal papillae have also been implicated. Early-onset disease in men (before age 35) is associated with metabolic syndrome and insulin resistance, whereas the cause of female-pattern hair loss remains unclear and is associated with an increased risk of polyendocrine metabolic ovarian syndrome.
How it is diagnosed
In men the diagnosis can usually be established from the clinical presentation, whereas in women it typically requires a more complex diagnostic evaluation. Assessment involves excluding other causes of hair loss and identifying the typical progressive pattern of androgenic alopecia. Trichoscopy can be used for further evaluation, and a biopsy may be needed to exclude other causes, with histology demonstrating perifollicular fibrosis. The Hamilton-Norwood scale grades severity in males and the Ludwig scale is used in women.
Who it affects
Pattern hair loss is the most common cause of hair loss. By the age of 50 it affects about half of males and a quarter of females. Some 30-50% of men have male androgenic alopecia by age 50, with an estimated 80% hereditary predisposition. According to the American Academy of Dermatology, female androgenic alopecia affects around 30 million women in the United States; although hair loss in women normally occurs after the age of 50, it is increasingly reported at earlier ages, including in women as young as 15 or 16.
Clinical overview sourced from encyclopaedic medical reference; see sources below. General information only — not a substitute for individual clinical assessment.
Treatment ladder
Conservative options are first-line where appropriate; surgical options are typically reserved for cases where lower-tier options are unsuitable or have failed. Decisions are individual and depend on clinical assessment.
Conservative
- Topical minoxidil
Over-the-counter 2% or 5% solution/foam applied twice daily. Slows progression and may produce modest regrowth in early-stage disease; effect lost on stopping. First-line in both men and women.
- Oral finasteride (men)
5-alpha reductase inhibitor 1mg daily. Effective in male pattern loss; sexual side effects in a small proportion. Requires prescription and ongoing use.
- Low-level laser therapy
FDA-cleared device-based therapy with modest evidence; an adjunct rather than a primary therapy.
Procedural
- Hair transplant — FUE · View procedure page
Follicular Unit Extraction: individual follicular units harvested from a donor area (usually occipital scalp) using small punches and implanted into thinning recipient sites. Leaves no linear scar; longer extraction time than FUT.
- Hair transplant — DHI
Direct Hair Implantation: an FUE variant using a Choi pen-like implanter; allows precise angle and depth control without prior site-making. Often marketed as a distinct technique.
- Hair transplant — FUT
Follicular Unit Transplantation: a linear strip of donor scalp is excised and dissected into follicular units. Leaves a linear donor-area scar but allows higher graft yields per session.
Surgical
- Scalp reduction (historic, rarely performed)
Surgical excision of bald scalp with advancement of hair-bearing scalp. Largely superseded by modern transplantation techniques and rarely performed today.
Related procedures
Sources
- [1]ISHRS — Standards of Practice for Hair Restoration Surgery — ishrs.org(accessed 2026-05-09)
- [2]Wikipedia — Pattern hair loss — en.wikipedia.org(accessed 2026-07-24)
Sources marked “on file” are held by The Treatment Registry but are not publicly accessible.