Alopecia areata is an autoimmune skin condition that affects millions of people worldwide and can occur at any age. When the body's own immune system mistakenly attacks the hair follicles, the result can be sudden, unexplained hair loss — often in well-defined round patches.
In this article, we explain exactly what alopecia areata is, how it differs from other forms of hair loss, what causes it, and what treatment options are available.
What is alopecia areata?
Alopecia areata is an autoimmune disorder in which the immune system's T-cells mistakenly attack the hair follicles — the small structures in the skin that produce hair. This attack causes the hair follicles to shrink and stop producing visible hair, resulting in hair loss.
The important thing to know is that alopecia areata is not contagious, and it is not caused by anything you have done wrong. The condition is also not directly dangerous to your physical health — but it can have a significant psychological impact.
What does alopecia areata look like?
Alopecia areata typically presents in the following ways:
- Round, smooth patches of hair loss: The most characteristic sign is well-defined, round or oval areas of complete hair loss. These patches are usually smooth and without scaling — unlike ringworm or scalp psoriasis, where the skin is scaly.
- Patches on the scalp: Hair loss is most commonly seen on the scalp, typically in one or several round patches. In some cases, the entire scalp loses all hair (alopecia totalis).
- Other hair-bearing areas: Alopecia areata can also affect the beard, eyebrows, eyelashes and other parts of the body. All body hair may be lost in the most severe form (alopecia universalis).
- Sudden onset: Hair loss often occurs very suddenly — some people only notice it when they see loose hairs on their pillow or in the bathroom.
When to seek urgent help
Alopecia areata leaves smooth, normal-looking skin — the follicles are intact and hair can regrow. If the scalp is instead red, scaly, tender or burning, or if you can no longer see the small openings where hairs emerge, it may be scarring (cicatricial) alopecia. In scarring alopecia the follicles are permanently destroyed and lost hair does not return. Have it assessed by a dermatologist without delay — treatment can stop further loss, but cannot restore what is already gone.
Why does alopecia areata happen?
Alopecia areata is caused by an autoimmune reaction in which the immune system's T-cells mistakenly identify hair follicles as foreign and attack them. The hair follicles enter a resting phase and temporarily stop producing hair.
How much of a role do genes play?
An important one. Up to 20% of people with alopecia areata have one or more family members with the same condition or another autoimmune disease.
Can stress trigger alopecia areata?
Yes, it can contribute. Severe physical or psychological stress can trigger or worsen alopecia areata. Stress affects the immune system and can contribute to the autoimmune reaction against hair follicles.
Which other conditions is it linked to?
Other autoimmune conditions. Alopecia areata is associated with thyroid diseases (Hashimoto's, Graves'), type 1 diabetes, vitiligo and rheumatoid arthritis. People with these conditions have a higher risk.
Because of the close link with the thyroid, a blood test of thyroid function (TSH, and thyroid antibodies where relevant) is standard when a diagnosis of alopecia areata is made. Further tests are only taken if symptoms point to them.
Who gets alopecia areata?
Alopecia areata can affect anyone — regardless of age, gender or ethnicity. However, there are some patterns:
- Age: The condition most often begins before the age of 30. About half of all cases start before the age of 20, with a smaller additional peak between 25 and 35.
- Prevalence: Approximately 2% of the population will develop alopecia areata at some point in their lives. In the USA alone around 6.7 million people live with the condition, and worldwide the figure is estimated at about 160 million.
- Family history: Up to 20% have a direct family history of alopecia areata or other autoimmune diseases.
What can you do about alopecia areata?
Although there is no universal cure, several treatments can help promote hair growth and slow further hair loss. Treatment depends on severity, age and individual factors.
Topical corticosteroids
Cream or lotion applied directly to the affected areas. First-line treatment for mild to moderate alopecia areata.
Intralesional steroid injections
Steroid is injected directly into the bald patches. Effective for adults with limited hair loss and preferred for those who do not respond to topical treatments.
Immunotherapy
Chemicals such as diphencyprone (DPCP) or squaric acid are applied to the skin to induce an allergic reaction that may redirect the immune system and stimulate hair growth. Used in more severe cases.
JAK inhibitors (oral medications)
Newer drugs such as baricitinib and ritlecitinib (approved by the EMA and FDA) are a major advance in treatment. They are approved for moderate-to-severe alopecia areata in adults — ritlecitinib from the age of 12. Treatment requires ongoing monitoring for infection, together with blood counts and lipid tests.
It is important to know that hair regrowth can be slow and requires patience. In some cases, hair grows back spontaneously — especially with limited alopecia areata. With more severe forms, treatment may need to be long-term.
Medical classification: Alopecia areata is classified as ED70.2 in the WHO's International Classification of Diseases (ICD-11). It is characterised by sudden, non-scarring hair loss due to an autoimmune reaction against the hair follicles.
Frequently asked questions
Is alopecia areata contagious?
No, alopecia areata is absolutely not contagious. It is an autoimmune condition — your body attacks its own hair follicles. You cannot infect others, and others cannot infect you.
Does hair grow back?
It depends on the severity. With limited alopecia areata, hair often grows back spontaneously within a year. With more widespread alopecia areata, alopecia totalis or alopecia universalis, spontaneous regrowth is less likely, but treatment can help.
When should I contact a dermatologist?
Contact a dermatologist as soon as you notice unexplained hair loss — especially if it occurs suddenly, in round patches, or if you have a family history of alopecia or other autoimmune diseases. If the scalp is also red, scaly or tender, seek assessment without delay.
Does alopecia areata affect the nails?
Yes, up to 50% of people with alopecia areata experience nail changes. These can include small dents (pitting), a rough surface, longitudinal ridges or white spots on the nails.
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Disclaimer: This article is for informational purposes only and does not replace professional medical advice. Always consult a doctor or dermatologist for personal guidance and assessment of skin changes.