How to recognise it
One or more round or oval patches appear over days or weeks. The skin is smooth and looks normal, with no scaling or scarring. Short broken hairs may sit at the edge. Nails can be pitted. In a small number of people it spreads to the whole scalp (alopecia totalis) or the whole body (alopecia universalis).
Why it happens
The immune system mistakes follicles for a threat and switches them off. The follicles are not destroyed, which is why hair can regrow. It is more common in people with thyroid disease, vitiligo, eczema or a family history. It isn't catching and it isn't caused by anything you did.
Treatment
Small patches often regrow without treatment. The HSE lists steroid creams and steroid injections into the patches among treatments, both given by a doctor. For severe alopecia areata, newer tablets called JAK inhibitors are licensed in the EU and are prescribed by dermatologists. No treatment changes the long-term course, and regrowth can't be promised.
Minoxidil is sometimes added. Finasteride and hair transplants are not treatments for alopecia areata.
Wigs and the grant
If your hair loss comes from an illness or its treatment, such as cancer treatment or certain types of alopecia, the Treatment Benefit Scheme pays up to €500 once a calendar year towards a wig or hairpiece, if you or your partner have enough PRSI contributions. It doesn't cover hair loss from ageing. How to claim.
What the doctor does
Most cases are diagnosed by looking. A GP checks the patches, the nails and the rest of your skin, and may order a blood test for thyroid function, because the two conditions often travel together. A dermatologist may use a handheld magnifier to look at the hairs at the edge of a patch.
For one or two small patches, waiting is a reasonable choice, since many regrow within a year. For patches that are spreading or upsetting, steroid cream or a course of small steroid injections into the patch is the usual first step. Regrowth often comes in white or fine at first and darkens later.
Looking after yourself
Sudden hair loss is hard, and it's normal to feel low or anxious about it. Tell your GP how it's affecting you. Patient support groups put people in touch with others who've been through it.
Questions people ask
Will my hair grow back?
For most people with a few patches, yes, usually within a year. It can return later. Wider or long-standing loss is harder to predict.
Is alopecia areata caused by stress?
Stress is often blamed, but the evidence is weak. It is an autoimmune condition.
Can a hair clinic treat it?
The medical treatments are prescribed by doctors. See your GP first, who can refer you to a dermatologist.
Can children get alopecia areata?
Yes. It often starts in childhood or early adult life. A child with patchy hair loss should always see a GP, who also checks for scalp ringworm.