Alopecia Areata Explained: A Patient's Guide to Autoimmune Hair Loss, Diagnosis, and Modern Treatments

Table of Contents

• Key Points
• Background: What Is Alopecia Areata?
• How Common Is Alopecia Areata, and Who Does It Affect?
• The Normal Hair Growth Cycle and "Immune Privilege"
• What Causes Alopecia Areata? The Big Picture
• The Immune Cells That Drive Alopecia Areata
• Cytokines: The Chemical Messengers Behind Hair Loss
• How Alopecia Areata Is Diagnosed and Measured
• Conventional Treatments: What Has Been Used for Decades
• Emerging Targeted Therapies: Biologics and Small Molecules
• Clinical Implications: What This Means for Patients
• Limitations: What Researchers Still Cannot Explain
• Practical Recommendations for Patients
• Frequently Asked Questions
• Source Information

Key Points

• Alopecia areata is an autoimmune, non-scarring hair loss affecting about 2% of people worldwide—roughly 147 million—and is the second most common hair loss disorder.
• Diagnosis is mainly clinical, supported by hair pull test, dermoscopy, or biopsy; the SALT score quantifies scalp hair loss severity.
• Conventional treatments include topical sensitizers, steroids, and immunosuppressants; newer JAK and PDE4 inhibitors act faster and show superior efficacy.
• Nearly 60% of patients experience psychological distress, and risks of other autoimmune diseases, hypertension, and high cholesterol are elevated.
• Current treatments relieve symptoms but do not cure; relapse is common, and immune memory cells persist at original hair loss sites.

Background: What Is Alopecia Areata?

Alopecia areata (AA) is an autoimmune condition — meaning the immune system mistakenly attacks the body's own tissue. In AA, that attack targets hair follicles, producing patchy or complete hair loss that does not leave scars (the medical term is "nonscarring alopecia"). It can affect the scalp, the body, or both.

The condition appears in several distinct clinical forms, and doctors classify patients partly by how much hair is lost and where:

• Patchy alopecia — one or more round bald spots
• Ophiasis — a band of hair loss wrapping around the back and sides of the scalp
• Sisaipho — hair loss that spares the edges of the scalp, the opposite pattern of ophiasis
• Diffuse alopecia — widespread thinning rather than distinct patches
• Perinevoidal alopecia — hair loss clustering around a mole (nevus)
• Marie Antoinette and Thomas More syndrome — named after historical figures described with this pattern
• Alopecia areata incognita (AAI) — sudden, extensive shedding that mimics other types of hair loss
• Alopecia totalis (AT) — complete loss of scalp hair
• Alopecia universalis (AU) — loss of all hair on the scalp and body

AA affects people of every age, gender, and ethnicity. The authors emphasize that despite decades of research, the precise cause remains elusive (unclear), and that is exactly what complicates the search for a cure.

Current treatments relieve symptoms but do not cure the disease. That gap leaves many patients facing ongoing financial strain and a reduced quality of life.

How Common Is Alopecia Areata, and Who Does It Affect?

AA ranks as the second most common hair loss disorder worldwide. It affects approximately 2% of the population — roughly 147 million individuals — and projections suggest that number will keep growing.

Prevalence rates (how many people have the condition at a given time) vary by geography and age. The incidence is higher in children than in adults, and rates are comparable between men and women.

The psychological burden is substantial and well documented. Psychological distress affects nearly 60% of AA patients — about 6 in 10. Reported problems include anxiety, insomnia, and diminished self-esteem, and these difficulties are most severe in patients with extensive hair loss. Anxiety-related disorders appear more often in women than in men.

AA also travels with other health conditions. Patients face an elevated risk of comorbidities (additional coexisting diseases), including:

• Other autoimmune disorders
• Hypertension (high blood pressure)
• Hyperlipidemia (high cholesterol and other blood fats)

This means AA is not simply a cosmetic concern. It is a systemic condition with measurable effects on mental and physical health.

The Normal Hair Growth Cycle and "Immune Privilege"

To understand AA, it helps to understand normal hair growth. Hair does not grow continuously. Instead, each follicle cycles through three phases, and every follicle runs its own independent cycle:

1. Anagen — the growth phase, when the hair actively lengthens
2. Catagen — the regression phase, when growth stops and the follicle shrinks
3. Telogen — the resting phase, before the hair eventually sheds

In healthy people, hair follicles enjoy something called immune privilege (IP). This is a protective shield that keeps the immune system from attacking the follicle — the same way the body protects certain delicate tissues from its own defenses. Immune privilege prevents immune cells from reacting to "foreign" or self-antigens (proteins the immune system could recognize as targets).

In AA, this protection breaks down. Specific triggers disrupt immune privilege, exposing self-antigens to the immune system. Once exposed, those antigens provoke an immune response.

The result is inflammation around the hair follicle, driven by IFN-γ (interferon-gamma, an immune signaling protein), CD8+ T cells (a type of killer immune cell), and other immune components. This inflammation forces the follicle to shift prematurely from the growth phase (anagen) into the resting phase (telogen), and it halts anagen progression at stage III. Hair loss follows.

The authors note that AA patients show this disruption across the board: follicles are pushed into premature telogen and catagen phases while anagen progression is arrested.

What Causes Alopecia Areata? The Big Picture

AA is multifactorial — meaning no single cause explains it. Four major forces interact: immune dysregulation, genetic susceptibility, environmental factors, and epigenetic alterations.

Genetics plays a central role. Evidence comes from familial clustering (AA running in families) and associations with specific human leukocyte antigen (HLA) alleles — inherited immune-system markers. Genome-wide association studies (GWAS), which scan the entire genetic code for disease-linked variations, have identified multiple susceptibility loci (regions of DNA associated with the disease). These findings reinforce the genetic basis of AA.

The dominant immunologic theory holds that AA arises from ectopic expression of hair follicle autoantigens. Ectopic expression means hair follicle proteins that are normally hidden become visible to the immune system. AA may also arise from localized inflammatory damage triggered by factors such as trauma, infection, or stress. This disrupts the follicle's immune privilege, upregulates MHC class I and II antigens (major histocompatibility complex proteins that flag cells to the immune system), and culminates in autoimmune attack.

Environmental factors can push a genetically vulnerable person toward disease. These include psychological stress, infections, and hormonal fluctuations.

Epigenetic modifications add another layer of complexity. Epigenetics refers to changes that affect how genes are switched on or off without altering the DNA sequence itself. In AA, two such changes matter: DNA methylation and histone acetylation. Both can dysregulate immune responses and disrupt hair follicle cycling.

The Immune Cells That Drive Alopecia Areata

The review devotes substantial attention to the specific immune cells involved. Each plays a different role.

CD8+NKG2D+ T cells are the key players. These are cytotoxic T lymphocytes (CTL) — killer cells of the adaptive immune system that normally defend against viruses, bacteria, and tumors. In AA, a specialized subset expressing the NKG2D receptor accumulates around the follicular bulb (the base of the hair follicle) in affected skin.

CD8 acts as a coreceptor that recognizes peptides presented by MHC class I proteins. NKG2D is an activating receptor found mainly on cytotoxic immune cells. Together, CD8+NKG2D+ T cells behave like a targeted strike force against the follicle.

The experimental evidence is striking:

• CD8+NKG2D+ T cells alone can induce AA-like lesions in healthy human skin grafts placed in SCID mice (mice with a severely compromised immune system that accept foreign tissue).
• Levels of these cells rise in the body after disease onset.
• In a mouse model of AA, CD8+NKG2D+ T cells produce IFN-γ through the JAK1 and JAK2 pathways.
• That IFN-γ then stimulates follicular epithelial cells (the cells lining the follicle) to release IL-15.
• IL-15 binds back to the surface of CD8+NKG2D+ T cells through the JAK1 and JAK3 pathways, triggering even more IFN-γ production.

This creates a positive feedback loop — a self-reinforcing cycle of inflammation. The authors state these findings collectively confirm that CD8+NKG2D+ T cells are sufficient on their own to initiate AA.

CD4+ T cells are a different T lymphocyte subset, developing in the thymus. They carry the CD4 glycoprotein, which binds MHC class II molecules. CD4+ T cells appear as perifollicular infiltrates (clusters of immune cells around the hair follicle) in AA patients. In experiments, CD4+ T cells taken from AA-affected mice and injected under the skin of C3H/HeJ mice induced generalized alopecia in the recipients. Research using the Dundee experimental bald rat model likewise points to CD4+ T cells as effectors of hair loss. Notably, CD8+ and CD4+ T cells contribute differently: CD8+ T cells induce localized AA, while CD4+ T cells lead to systemic AA.

Invariant NK T cells (iNKT cells) are unconventional T lymphocytes that recognize lipid antigens such as α-galactosylceramide (α-GalCer) presented by CD1d molecules. They are 8- to 10-fold larger than both NK cells and conventional T cells, are abundant in killer cytokines, and bridge innate and adaptive immunity. In an animal model with human scalp skin xenografts, stimulating iNKT cells with α-GalCer halted the progression of AA lesions and promoted hair regrowth. This positions iNKT cells as potential therapeutic targets.

Regulatory T cells (Tregs) are immunosuppressive cells identified by the markers Foxp3, CD25, and CD4. They maintain immune balance. When Tregs are deficient in number or impaired in function, immune tolerance breaks down — a hallmark of autoimmune disease. Some studies show that IL-2, IL-10, and transforming growth factor-β (TGF-β) secreted by Tregs can suppress CD8+NKG2D+ T cells and reduce autoantigen production by hair follicle epithelial cells. The authors caution, however, that these findings remain inconclusive and need further study.

Tissue-resident memory (TRM) T cells live permanently in tissues and act as a first line of defense against reinfection. They carry markers such as CD44, CD49, CD69, and CD103, and fall into two subsets: IFN-γ-producing TRM1 and IL-17-producing TRM17. Upon re-exposure to antigens, they rapidly release IFN-γ and TNF-α. This helps explain a familiar clinical pattern: recurrent AA typically returns to the original site of hair loss, because T cell clones persist at the lesion. Studies show upregulation of CD103+CD69+ TRM T cells at lesion sites in AA patients. The authors conclude TRM cells have a substantial impact on both the development and recurrence of AA.

Dendritic epidermal T cells (DETCs) are a specialized subset of γδ T cells. They share features with conventional αβ T cells, including upregulated NKG2D expression and the ability to secrete cytotoxic and inflammatory cytokines. Stimulated by self-antigens, they may participate in AA by producing IFN-γ that promotes CD8+NKG2D+ T cell activity and triggers the breakdown of hair follicle immune privilege. Observational study of hair follicles found DETCs rarely present in healthy skin but significantly elevated in AA patients. The authors note that further studies are needed to clarify their exact contribution.

Other cell types contribute as well. Mast cells and eosinophils infiltrate the skin lesions of AA patients:

• Mast cells sit near blood vessels and hair follicles. Their numbers correlate with CD8+ T lymphocytes around deep hair follicles. Infiltration in mesenchymal, perivascular, and perifollicular regions is more pronounced in AA patients than in healthy controls. Through degranulation (releasing their contents), cytokine release, and enhanced interaction with CD8+ T cells, mast cells worsen the inflammatory response.
• Eosinophils typically sit at the edges of enlarged AA lesions and can be present at all disease stages. They are found mainly around hair follicles during the late regressive and resting phases. Eosinophilic infiltration tends to be higher in patients with diffuse AA.
• Melanocytes (pigment-producing cells) matter too. Melanin-associated antigens from follicular melanocytes activate CD8+NKG2D+ T cells, prompting their attack.

Together, this collection of cells paints a complex picture of interacting immune activity around the hair bulb.

Cytokines: The Chemical Messengers Behind Hair Loss

Cytokines are small signaling proteins that immune cells use to communicate. In AA, several play decisive roles.

IFN-γ (interferon-gamma) is a secreted glycoprotein of roughly 17 kDa (kilodaltons, a unit of molecular weight) and the only member of the type II interferon family. CD4+ T cells, CD8+ T cells, γδ T cells, and NK cells produce large amounts of it when stimulated by cytokines such as IL-12, IL-15, and IL-18. NK T cells, B cells, and antigen-presenting cells (APCs) make smaller amounts.

IFN-γ activates macrophages, induces MHC-II-like molecule expression, and stands as one of the most important natural mediators of immune and inflammatory responses. It signals mainly through the JAK–STAT pathways. It is considered a pivotal factor in breaking down the hair follicle's immune privilege.

The experimental evidence for IFN-γ is strong:

• When exogenous (externally given) IFN-γ was injected into female C3H/HeJ mice, the treated mice developed hair follicle atrophy during the growth phase — something control mice rarely showed.
• When skin from C3H/HeJ mice with AA was transplanted into mice lacking the IFN-γ gene and into wild-type mice, 90% of the wild-type mice developed AA, while the IFN-γ-deficient mice did not develop the condition at all.
• In humans, affected skin of AA patients shows significantly enhanced IFN-γ-responsive gene expression compared with normal controls, and serum IFN-γ levels are markedly elevated in people with AA.

TNF-α (tumor necrosis factor-alpha) is a 17.4 kDa proinflammatory cytokine produced mainly by macrophages and monocytes, but also by neutrophils, CD4+ T cells, and NK cells. Multiple studies consistently find elevated serum TNF-α levels and increased TNF mRNA in peripheral blood mononuclear cells of AA patients compared with healthy individuals. Notably, patients with atopic AA (AA plus allergic conditions such as eczema or asthma) had even higher serum TNF levels than those without atopic AA. Higher TNF-α levels are also seen in patients with a SALT score of 25% or greater compared with those below 25%; SALT (Severity of Alopecia Tool) is a standardized scale for measuring how much scalp hair has been lost. Disease duration also correlates positively with TNF-α expression.

IL-17 (interleukin-17) is a group of six structurally similar proinflammatory cytokines: IL-17A, IL-17B, IL-17C, IL-17D, IL-17E, and IL-17F. They are made by CD4+ T cells, CD8+ T cells, neutrophils, NK cells, and γδ T cells. IL-17 recruits immune cells and its effects amplify when it coexists with other proinflammatory cytokines. IL-17-secreting cells are present across all AA types, with a higher prevalence in multiple patchy alopecia and lower occurrence in alopecia totalis, and they localize predominantly at the periphery of the hair follicle. Elevated Th17 cells and IL-17 are consistently observed in AA patients, with a direct correlation between serum IL-17A, IL-17E, and IL-17F levels and disease severity.

IL-2 (interleukin-2) is a key immune regulator — a single-chain polypeptide of 15.5 kDa — secreted mainly by CD4+ T cells after activation through T cell receptors (TCRs) and CD28 costimulatory signaling. It is also produced by CD8+ T cells, NK cells, NKT cells, and dendritic cells (DCs). Heterozygous mice deficient in IL-2 (mice carrying only one working copy of the gene) show reduced expression of IL-2, IL-4, IL-10, IL-12, IFN-γ, TNF-α, and TGF-β. When skin grafts from AA-affected C3H/HeJ mice were transplanted into IL-2-deficient mice, AA progression slowed relatively.

In humans, AA patients have higher serum IL-2 levels than healthy controls, and their peripheral blood mononuclear cells contain higher levels of IL-2 mRNA. The number of bald plaques on the scalp, the degree of alopecia, and the length of the condition all correlate positively with serum IL-2 levels. One caveat: some studies suggest only patients with generalized AA show elevated serum IL-2, while those with localized AA show no significant change.

IL-15 (interleukin-15) is a strong proinflammatory cytokine that is structurally identical to IL-2. It is produced by monocytes, macrophages, fibroblasts, keratinocytes, mast cells, neuronal cells, and dendritic cells. A comprehensive transcriptional analysis of AA lesions in both humans and C3H/HeJ mice revealed upregulation of the IL-15 gene, and blocking the IL-15β receptor significantly slowed AA progression. AA patients also show increased expression of IL-15 and its receptor subunit IL-15Rα in hair follicles, along with elevated serum IL-15 levels. Serum IL-15 correlates positively with AA severity, establishing it as a pivotal signaling molecule in the disease.

IL-12 (interleukin-12) is a heterodimer — a protein built from two different parts: an α-subunit (IL-12p35) and a β-subunit (IL-12p40), the latter shared structurally with IL-23. IL-12 is active only when both subunits are present. It is produced mainly by dendritic cells, macrophages, and B cells in response to microbial pathogens. AA patients show significantly higher serum IL-12 levels and increased IL-12 mRNA in peripheral blood mononuclear cells compared with healthy controls. IL-12 levels in these cells correlate positively with the severity and duration of hair loss.

Beyond these individual molecules, AA patients show significant presence of three broad cytokine families that contribute to the condition:

• Th1 cytokines — IL-2, IFN-γ, TNF-α, IL-12, and IL-18
• Th2 cytokines — IL-4, IL-5, IL-6, IL-9, IL-10, IL-13, IL-17E, IL-31, and IL-33
• Th17 cytokines — IL-17, IL-17F, IL-21, IL-22, and IL-23

Other cytokines also play a critical role in maintaining hair follicle immune privilege and in restoring it once it has collapsed. The authors liken these protective molecules to a "follicular IP security" system.

How Alopecia Areata Is Diagnosed and Measured

Diagnosis of AA rests primarily on clinical presentation — what the doctor sees and hears during the examination. There is no single blood test that confirms the disease.

Doctors supplement the clinical assessment with several auxiliary tests:

• Hair pull test — gentle traction on a small group of hairs to see how many come out and at what growth phase
• Dermoscopy — magnified examination of the scalp surface to identify characteristic patterns
• Histopathological examination — microscopic study of a small skin biopsy sample to look for perifollicular inflammation and other diagnostic features

Assessing severity matters because treatment choices and prognosis depend on how much hair has been lost and how quickly. The review highlights recent advancements in severity assessment tools, including the SALT score (Severity of Alopecia Tool), which quantifies the percentage of scalp hair loss. A SALT score of 25% or higher appears to track with higher TNF-α levels, suggesting the tool captures real biological differences between milder and more severe disease.

Conventional Treatments: What Has Been Used for Decades

Traditional AA therapy aims to calm the immune attack on the follicle. Several categories are in common use.

Topical contact sensitizers work by deliberately provoking a mild allergic reaction on the scalp, which redirects immune activity. The two named in the review are:

• Diphenylcyclopropenone (DPCP)
• Squaric acid dibutylester (SADBE)

Glucocorticosteroids (steroid medications that suppress inflammation) are used both systemically (affecting the whole body) and topically (applied directly to the skin).

Systemic immunosuppressants are also commonly prescribed. These include:

• Methotrexate
• Azathioprine
• Cyclosporine (CsA)

Beyond these mainstays, several investigational approaches have been tried:

• Cryotherapy (freezing treatment)
• Methyl aminolevulinic acid-based photodynamic therapy (a light-activated treatment)
• Topical calcineurin inhibitors (CNIs)
• Topical prostaglandin analogs, such as latanoprost or bimatoprost
• Pulsed infrared diode laser therapy
• Antihistamines

The authors are candid about the shortcomings of these options. Many conventional treatments show limited efficacy, cause adverse effects, suffer from poor compliance (patients find them hard to stick with), and carry high relapse rates after discontinuation (hair loss returns once treatment stops). These limitations make rigorous clinical monitoring necessary — patients need regular follow-up.

Emerging Targeted Therapies: Biologics and Small Molecules

The therapeutic landscape is shifting. Two categories of newer drugs show particular promise as targeted interventions for AA.

Biologics are engineered proteins designed to block specific immune pathways. Small-molecule drugs include two classes highlighted in the review:

• JAK inhibitors — drugs that block the Janus kinase (JAK) signaling pathway
• PDE4 inhibitors — drugs that block phosphodiesterase 4 (PDE4)

Why does blocking JAK matter so much in AA? Because the JAK–STAT pathway sits directly at the center of the disease process. As described earlier, CD8+NKG2D+ T cells use JAK1 and JAK2 to produce IFN-γ, and they use JAK1 and JAK3 to respond to IL-15. Breaking this loop interrupts the self-sustaining cycle of inflammation.

The authors describe a clear advantage over traditional therapy. Compared with conventional treatments, biologics and small molecules:

1. Act rapidly
2. Demonstrate superior efficacy
3. Enable precise modulation of disease pathways

The review characterizes this as a paradigm shift in AA management — a fundamental change in how the disease is approached. The review states that targeted therapies are poised to redefine treatment standards.

Clinical Implications: What This Means for Patients

The most important practical message is that AA is an immune disease with identifiable molecular targets, not an unexplained cosmetic problem. That understanding is already changing treatment.

Several implications follow directly from the science:

• Targeted therapy is now possible. Because IFN-γ, IL-15, and the JAK–STAT pathway sit at the center of the disease, drugs that interrupt them address the underlying mechanism rather than just the symptom.
• Faster results with better outcomes. The review reports that newer agents act rapidly and show superior efficacy compared with older options — and older options often fail, cause side effects, or stop working when discontinued.
• Recurrence has a biological explanation. TRM T cells persist at the original lesion site, which is why AA tends to return in the same place. This helps patients understand why long-term monitoring may be needed.
• Mental health is part of the disease. With psychological distress affecting nearly 60% of AA patients, and anxiety disorders more common in women, emotional support is not optional — it is part of comprehensive care.
• Screening for related conditions matters. The elevated risk of other autoimmune disorders, hypertension, and hyperlipidemia means blood pressure and cholesterol monitoring are reasonable parts of a patient's overall care.

The authors also point out that AA affects all ages, genders, and ethnicities. AA appears more often in children than adults, and occurs at comparable rates in men and women. No patient group can be assumed to be at low risk.

Limitations: What Researchers Still Cannot Explain

The review is explicit about the gaps in knowledge. Several limitations stand out.

The precise etiology remains elusive. Etiology means cause. Despite significant advances in identifying contributing factors, researchers still cannot pinpoint what starts AA in any individual patient.

Substantial gaps persist in understanding the full spectrum of molecular mechanisms. The disease involves immune dysregulation, genetics, epigenetics, hair cycle disturbance, and environmental influence — and how these interact is not fully mapped.

The Treg findings are inconclusive. Some studies link regulatory T cells to AA pathogenesis and show their secretions (IL-2, IL-10, TGF-β) can suppress CD8+NKG2D+ T cells. The authors state these findings warrant further investigation.

The role of DETCs needs clarification. While DETCs are significantly elevated in AA patients compared with healthy individuals, their exact contribution to the disease remains undefined.

Some cytokine findings conflict. For IL-2, most studies show elevated levels in AA patients. Some research suggests only patients with generalized AA have elevated serum IL-2, while those with localized AA show no significant change.

Curative therapy does not yet exist. Current treatments provide symptomatic relief only, and the persistent limitations of conventional therapy — limited efficacy, adverse effects, poor compliance, and high relapse rates — leave patients with unmet needs.

Practical Recommendations for Patients

Based on what this review establishes, patients and families can take several concrete steps.

1. Get a proper diagnosis from a dermatologist. AA is diagnosed primarily by clinical examination, supported when needed by a hair pull test, dermoscopy, or a scalp biopsy. Getting the diagnosis right matters because treatment differs by condition.
2. Ask about disease severity and how it will be tracked. Tools such as the SALT score quantify how much scalp hair has been lost. Tracking this over time gives you and your doctor an objective way to judge whether a treatment is working.
3. Discuss both conventional and targeted options. Conventional approaches — topical contact sensitizers such as DPCP and SADBE, topical or systemic steroids, and immunosuppressants such as methotrexate, azathioprine, and cyclosporine — remain in use. But ask specifically whether biologics or small-molecule drugs (JAK inhibitors, PDE4 inhibitors) might be appropriate, since the review reports they act faster and show superior efficacy.
4. Plan for the possibility of relapse. Relapse rates are high after stopping conventional treatment, and immune memory cells persist at the original site of hair loss. Ask your doctor what the follow-up plan is before you start any therapy.
5. Treat the psychological side seriously. Nearly 60% of AA patients experience psychological distress, including anxiety, insomnia, and reduced self-esteem. Ask about mental health support as part of your care, not as an afterthought.
6. Get screened for related conditions. Because AA patients face higher risks of other autoimmune diseases, hypertension, and hyperlipidemia, regular blood pressure and cholesterol checks are reasonable.
7. Be patient with the science, but stay informed. The field is moving quickly, and the review frames targeted therapy as a paradigm shift. New options are emerging, and understanding the biology — especially why JAK and IL-15 pathways matter — can help you have a more productive conversation with your clinician.

One note of caution: this review summarizes research rather than prescribing individual treatment. Any decision about medication should be made with a qualified dermatologist who knows your history.

Frequently Asked Questions

What is alopecia areata?

Alopecia areata is an autoimmune condition in which the immune system mistakenly attacks hair follicles, causing patchy or complete hair loss that does not leave scars. It can affect the scalp, body, or both. It appears in several forms, from round bald spots to complete scalp hair loss (alopecia totalis) or loss of all scalp and body hair (alopecia universalis).

How common is alopecia areata and who gets it?

Alopecia areata is the second most common hair loss disorder worldwide. It affects about 2% of the population, roughly 147 million people, and that number is projected to grow. It occurs in people of every age, gender, and ethnicity. Incidence is higher in children than adults, and rates are comparable between men and women.

What causes alopecia areata?

The cause is multifactorial and not fully understood. Four forces interact: immune dysregulation, genetic susceptibility, environmental factors, and epigenetic changes. Hair follicles normally have an immune privilege that breaks down, exposing hidden hair follicle proteins to the immune system. This triggers inflammation driven by IFN-γ, CD8+ T cells, and other immune components, forcing follicles into premature resting phases.

How is alopecia areata diagnosed?

Diagnosis rests mainly on clinical examination—what the doctor sees and hears. There is no single blood test that confirms the disease. Doctors may add a hair pull test, dermoscopy (magnified scalp examination), or a small scalp biopsy examined under a microscope. Severity is often tracked with the SALT score, which quantifies the percentage of scalp hair loss.

What treatments are available for alopecia areata?

Conventional treatments include topical contact sensitizers (DPCP, SADBE), topical or systemic steroids, and immunosuppressants such as methotrexate, azathioprine, and cyclosporine. Newer targeted drugs include JAK inhibitors and PDE4 inhibitors. Compared with conventional treatments, these targeted therapies act rapidly and show superior efficacy. However, current treatments relieve symptoms but do not cure the disease.

What are the psychological effects of alopecia areata?

Psychological distress affects nearly 60% of patients—about 6 in 10. Reported problems include anxiety, insomnia, and diminished self-esteem, and these are most severe in patients with extensive hair loss. Anxiety-related disorders appear more often in women than in men. Emotional support is part of comprehensive care, not an afterthought.

Does alopecia areata increase the risk of other health conditions?

Yes. Patients face an elevated risk of other autoimmune disorders, hypertension (high blood pressure), and hyperlipidemia (high cholesterol and other blood fats). This means alopecia areata is not simply a cosmetic concern; it is a systemic condition with measurable effects on mental and physical health. Regular blood pressure and cholesterol checks are reasonable parts of overall care.

I was just diagnosed with alopecia areata and my dermatologist wants to start me on steroids — when should I get a second opinion?

Consider a second opinion when the diagnosis rests only on clinical examination without a hair pull test, dermoscopy, or scalp biopsy. Also consider a second opinion when conventional therapy is proposed without discussing targeted options. Conventional treatments show limited efficacy, adverse effects, poor compliance, and high relapse rates after discontinuation, while JAK inhibitors and PDE4 inhibitors act faster and show superior efficacy. Because severity tracking with the SALT score guides treatment choices, an independent review can confirm the diagnosis and whether newer agents are appropriate. Diagnostic Detectives Network provides independent expert second opinions.

Source Information

Original article title: Alopecia Areata- Pathogenesis, Diagnosis, and Therapies

Authors: Tianyou Ma, Tingrui Zhang, Fengze Miao, Jun Liu, Quangang Zhu, Zhongjian Chen, Zongguang Tai, and Zhigao He. Tianyou Ma and Tingrui Zhang contributed equally to this work.

Author affiliations: Department of Pharmacy, Longhua Hospital of Shanghai University of Traditional Chinese Medicine, Shanghai, China; Shanghai Skin Disease Hospital, School of Medicine, Tongji University, Shanghai, China; Shanghai Engineering Research Center of External Chinese Medicine, Shanghai, China.

Corresponding authors: Zhongjian Chen, Zongguang Tai, and Zhigao He.

Publication: MedComm, 2025; volume 6, article e70182. Published by Sichuan International Medical Exchange & Promotion Association (SCIMEA) and John Wiley & Sons Australia, Ltd. This is an open-access article distributed under the terms of the Creative Commons Attribution License.

Article history: Received 9 October 2024; revised 17 March 2025; accepted 26 March 2025.

Funding: This work was supported by the National Natural Science Foundation of China (82172706 and 82373274), the Science and Technology Commission of Shanghai Municipality (22S21902700 and 23S21900800), and the Shanghai Municipal Health Commission (2024ZZ1009 and 202240370).

Keywords: alopecia areata, autoimmunity, diagnosis, pathogenesis, targeted therapy.

This patient-friendly article is based on peer-reviewed research.