Alopecia Areata: What Causes It?
Also known as: Patchy hair loss, Alopecia totalis, Alopecia universalis
What is alopecia areata?
Alopecia areata is an autoimmune disease that causes hair loss in patches, without scarring or visible damage to the scalp. The lifetime risk of developing it is estimated at about 2% of the general population, and it affects women and men about equally. Most people develop it in their teens, twenties, or thirties. Alopecia areata results from the immune system attacking hair follicles, mistakenly treating them as foreign invaders to eliminate. It can range from a single isolated patch to complete scalp hair loss (alopecia totalis) or even loss of all body hair (alopecia universalis).
Causes and risk factors
Alopecia areata is an autoimmune disease whose exact cause remains unclear, though several contributing factors have been identified. Genetics play a role: scientists have linked a number of genes to the disease, and first-degree relatives of someone with alopecia areata carry a higher risk than the general population, estimated at roughly 6% to 8%. Significant psychological stress, emotional shocks, and certain viral infections can trigger or worsen flare-ups in people who are already predisposed, though in most cases there is no obvious trigger. Alopecia areata is also associated with other autoimmune conditions such as thyroid disease and vitiligo, suggesting a shared immune vulnerability.
Symptoms
The main sign is the sudden appearance of round or oval patches without hair, with smooth skin and no visible inflammation. These patches most often affect the scalp, but can also affect the beard, eyebrows, or eyelashes. Around the edges of the patches, “exclamation mark hairs” that are thinner near the base are sometimes seen, and they are considered characteristic of the disease. The course is unpredictable: spontaneous regrowth within months, or progression to a more severe form. Nail changes such as pitting and ridging affect roughly 10% to 15% of patients, and are more common in people with more extensive hair loss.
Diagnosis
Diagnosis of alopecia areata is clinical, made by a dermatologist who examines the areas of hair loss and the nails, often using a handheld magnifying device (dermoscopy, sometimes called trichoscopy) to look closely at the hair follicle openings. In some cases, a skin biopsy taken from the edge of an active patch may be done to confirm the diagnosis and rule out other causes of hair loss. Blood tests, including thyroid or autoimmune testing, may be offered if alopecia areata occurs alongside other autoimmune signs.
Available treatments
There is no definitive cure, but several options can stimulate regrowth:
- Corticosteroids, applied topically or injected directly into the patches to reduce inflammation. Injections are often used for patchy alopecia areata.
- Minoxidil, applied to the scalp to stimulate hair regrowth
- Contact immunotherapy, for more extensive cases
- JAK inhibitors (Janus kinase inhibitors), newer medications approved by the FDA for severe alopecia areata. Baricitinib and deuruxolitinib are approved for adults, and ritlecitinib from age 12 up
- Psychological support, since the emotional impact is often significant and depression and anxiety are more common in people with the condition
Treatment choice depends on how extensive the alopecia areata is and how it is progressing.
Prevention and practical tips
There is no specific way to prevent alopecia areata, since it is an autoimmune condition. That said, managing stress through relaxation techniques, quality sleep, and psychological support may help some people cope with flare-ups. Wigs, scarves, or hair prostheses can help people live more comfortably with the condition day to day, and patient support groups offer valuable support. Because people with alopecia areata have a higher risk of conditions such as thyroid disease and other autoimmune diseases, regular visits to a primary care doctor are worthwhile.
When should you see a doctor?
Any unexplained patchy hair loss should be evaluated by a board-certified dermatologist, who can confirm the diagnosis, rule out other causes of hair loss, and go over your treatment options. Alopecia areata can affect the beard, eyebrows, and eyelashes as well as the scalp, so mention those areas too. Reach out for support if the hair loss is affecting your mood or daily life: depression and anxiety are more common in people with the condition, and a mental health professional can help.
Key takeaway: Alopecia areata is an unpredictable autoimmune disease that causes hair loss without scarring or lasting damage to the follicles. A dermatologist can confirm the diagnosis and go over the treatments that help hair grow back.
Sources
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), overview, age of onset, causes and triggers, symptoms, and spontaneous regrowth
- NIAMS, Alopecia Areata: Diagnosis, Treatment, and Steps to Take, diagnosis, wigs and scarves, depression and anxiety, and follow-up with a primary care doctor
- MedlinePlus, U.S. National Library of Medicine, genetics, sex distribution, and associated conditions
- American Academy of Dermatology (AAD), alopecia areata overview, patient education on hair loss and seeing a board-certified dermatologist
- American Academy of Dermatology (AAD), alopecia areata diagnosis and treatment, corticosteroids, minoxidil, contact immunotherapy, and the FDA-approved JAK inhibitors with their approved ages
- StatPearls, NCBI Bookshelf (NIH), clinical review: lifetime risk, triggers, exclamation mark hairs, nail involvement, biopsy, and thyroid testing
- Rochester Epidemiology Project, PMC (NIH), lifetime incidence risk of alopecia areata
- Epidemiology and burden of alopecia areata: a systematic review, PMC (NIH), age of onset, comorbidities, and psychiatric burden
- Recent advances in the genetics of alopecia areata, PMC (NIH), familial risk in first-degree relatives and heritability