Causes & Diagnosis

Androgenetic alopecia — the genetic one

Inherited sensitivity to DHT, progressive, permanent, and by far the most common cause in both men and women. This is the category transplantation was designed for, because the donor area is genetically spared.

Telogen effluvium — the temporary one

A shock — childbirth, major surgery, severe illness, crash dieting, acute psychological stress — pushes a large number of follicles into the resting phase at once. Three to six months later they shed together, and it is alarming.

It resolves on its own once the trigger is gone, usually within six to nine months. Operating during an active effluvium is a mistake: the picture is not stable and the shedding is not what it appears to be.

Alopecia areata — the autoimmune one

Well-defined round patches of complete loss, caused by the immune system attacking the follicle. It can regrow spontaneously and can relapse. Transplanting into an active or recently active area risks the transplanted hair being attacked too, which is why we require a long period of stability before considering surgery.

Scarring alopecias — the urgent one

Lichen planopilaris, frontal fibrosing alopecia, central centrifugal cicatricial alopecia and folliculitis decalvans destroy the follicle and replace it with scar tissue. The loss is permanent and the process is often still active.

These need a dermatologist and medical suppression first. Transplanting into an active scarring alopecia fails — the grafts are destroyed by the same process. If you have redness, scaling, burning, itching or tenderness along the edge of your loss, that is worth investigating before anything else.

Traction alopecia — the mechanical one

Years of tension from tight braids, locs, weaves, extensions or a habitual tight ponytail pull follicles out permanently, typically along the hairline and temples. Caught early it reverses when the tension stops. Left long enough it becomes permanent — and then it transplants very well, once the styling that caused it has changed.

How it is actually diagnosed

Trichoscopy — magnified examination of the scalp — separates most of these within minutes: miniaturization variance points to androgenetic loss, yellow dots and exclamation-mark hairs to areata, loss of follicular openings to a scarring process. A pull test measures active shedding. Bloodwork covers ferritin, thyroid, and hormones where the history suggests it.

None of this can be done from a photograph, which is worth remembering when a clinic quotes you a graft number from two pictures sent over WhatsApp.

Sorting the reversible from the permanent

The single most useful question in hair loss is whether the follicle is still alive. Miniaturizing follicles are alive and can respond to treatment. Scarred follicles are gone, and no medication, injection or device will bring them back — only transplantation into or around the scarred area, where appropriate, can add hair.

That distinction cuts across every cause. Telogen effluvium after illness, surgery, childbirth or crash dieting is dramatic and almost entirely reversible, typically recovering over six to twelve months once the trigger resolves. Androgenetic loss is gradual and only partly reversible, and only while follicles are still miniaturizing rather than absent. Scarring alopecias — lichen planopilaris, frontal fibrosing alopecia, discoid lupus — destroy follicles permanently, and their early symptoms of itching, burning, redness or scale are a reason to see a dermatologist quickly rather than to book surgery.

Things blamed for hair loss that mostly are not

A large amount of the anxiety around hair loss is spent on factors that have little to do with it. Hats do not cause baldness. Frequent washing does not, and washing less to 'save' hair simply delays the appearance of hairs that had already shed. Hair dye and normal styling do not cause pattern loss, though heat and chemical damage cause breakage, which looks like loss and behaves differently.

Stress is more nuanced: acute severe stress genuinely triggers telogen effluvium, and that is real and temporary; chronic ordinary stress is not an established cause of androgenetic loss. Diet matters at the extremes — significant iron, protein or caloric deficiency will shed hair — but supplements do not help anyone who is not deficient, and megadoses of some nutrients, selenium and vitamin A in particular, cause hair loss rather than preventing it.

• Worth investigating: sudden diffuse shedding, itching or burning, visible scalp inflammation, patchy round bald spots, loss with a broken hairline in the front only.
• Not worth worrying about: hats, frequent washing, ordinary dye, brushing, cold weather, the hairs on your pillow after a haircut.