What is androgenetic alopecia?
Androgenetic alopecia in men, and female pattern hair loss in women, are the most common forms of non-scarring hair loss. The picture is characterised by a gradual miniaturisation of the hair follicles, so that the hair becomes progressively finer in a typical pattern. It can begin from puberty onwards, and the course is chronic and progressive.
What does it look like?
In men, there is recession at the temples and/or thinning over the crown (the classic pattern). In women, there is diffuse thinning over the crown with a widening central parting, while the frontal hairline is often spared (the so-called “Christmas-tree” pattern). The hair does not fall out in patches; instead the whole area gradually becomes thinner.
What causes it?
Dihydrotestosterone (a form of the male hormone testosterone) and the androgen receptor play an important role, especially in men. Besides hormones, other factors are also involved, including local inflammation; the exact contribution varies from person to person. There is often a hereditary predisposition.
How is the diagnosis made?
The diagnosis is usually made from the history and examination, sometimes supported by trichoscopy (magnified examination of the scalp), which shows hairs of varying thickness and follicle miniaturisation. Rapid progression, inflammation, scarring or an unusual pattern calls for investigation of other causes, such as alopecia areata, telogen effluvium (diffuse shedding after illness, stress or childbirth), traction alopecia, fungal infection of the scalp, or thyroid and iron problems. Women with irregular periods, acne or excess body hair may need hormonal assessment.
How is it treated?
It is important to know from the outset that this is a chronic, often progressive condition: treatment usually aims at stabilising the loss and achieving limited regrowth, and long-term maintenance is generally needed. It is useful to take photographs at the start and to assess the effect after 6–12 months.
Topical minoxidil
Minoxidil applied to the scalp is the mainstay of treatment for both men and women. It should usually be continued for at least 6 months before its effect is judged. Possible side effects are irritation, an initial increase in shedding, and unwanted facial or body hair; systemic effects are rare.
5-alpha-reductase inhibitors (men)
Finasteride (1 mg once daily) can be considered for men when minoxidil is insufficient or the stage is more advanced. When the response is insufficient, dutasteride is sometimes used. These medicines can cause sexual side effects (affecting libido, erection or ejaculation); mood changes or suicidal thoughts should be reported urgently. These options are discussed and prescribed by a doctor.
Anti-androgens (women)
For female pattern hair loss, when minoxidil is insufficient or excess androgen activity is suspected, a systemic anti-androgen such as spironolactone can be considered (off-label). Hormonal assessment may be appropriate first.
Other options
Hair transplantation can be considered in suitable cases, and a hairpiece can help when medical or surgical treatment is not suitable.
When to see a doctor
See your GP or a dermatologist for sudden or rapid hair loss, scalp redness, scaling, pustules, scarring, loss of the follicle openings, or an unusual pattern, so other causes can be excluded. Discuss treatment with a clinician before using systemic medicines, and promptly report mood changes, suicidal thoughts, heart or circulation symptoms, or possible pregnancy while on these medicines.