Alopecia Areata: Why The Immune System Attacks Hair Follicles

Did you know that the immune system, the very thing that protects us from harmful bacteria and viruses, can sometimes turn against our own bodies? This unusual event happens in certain autoimmune conditions, and one of the most visible forms of it is alopecia areata. In this condition, the immune system mistakenly attacks healthy hair follicles, leading to sudden, patchy hair loss. For many, the experience can be confusing and distressing, especially when the cause is not immediately clear.

This happens when the immune system identifies the hair follicles as “foreign invaders” and launches an attack, causing inflammation and halting hair growth. While the follicles aren’t destroyed, their function is temporarily disrupted, which means hair can fall out in round or oval patches on the scalp or other parts of the body which is hair-bearing¹. The good news is that, in many cases, hair can grow back, but understanding why this happens in the first place is key to managing and treating the condition effectively.

What exactly is alopecia areata?

Alopecia areata is an autoimmune disorder that primarily affects hair follicles, the tiny structures in the skin responsible for growing hair. Unlike male or female pattern baldness, which typically results from hormonal and genetic factors, alopecia areata is caused by immune system dysfunction. The condition can develop at any age, although it often first appears during childhood or early adulthood².

The hallmark symptom of alopecia areata is the sudden appearance of one or more round bald patches, most commonly on the scalp. However, it can also affect the eyebrows, eyelashes, beard, or even body hair. The skin in these patches usually remains smooth and unscarred. Some people experience only minor hair loss, while others may lose more hair over time, sometimes progressing to total scalp hair loss (alopecia totalis) or complete body hair loss (alopecia universalis).

Why does the immune system attack hair follicles?

Under normal circumstances, the immune system’s T cells protect the body by attacking foreign pathogens such as bacteria or viruses. In alopecia areata, however, these T cells infiltrate the hair follicle bulb (the base of the follicle where hair growth begins) and mistakenly target it as a threat³. This immune response causes inflammation around the follicles, interrupting the normal hair growth cycle.

Although the exact trigger for this autoimmune reaction is still being researched, several factors appear to contribute to it. Genetics plays a significant role; people with a family history of autoimmune conditions such as thyroid disease, vitiligo, or type 1 diabetes have a higher likelihood of developing alopecia areata⁴. Environmental triggers, such as viral infections, high stress levels, and even physical trauma, may also activate the immune response in individuals who are genetically predisposed.

The link between stress and alopecia areata

Many people who develop alopecia areata notice that it often appears during or after periods of intense emotional or physical stress. While stress alone isn’t considered a direct cause, it can act as a trigger by affecting immune regulation and inflammation in the body⁵. Chronic stress, for example, has been shown to alter the balance of hormones and immune signals, potentially making the immune system more reactive to the body’s own tissues.

That’s why addressing stress through relaxation techniques, mindfulness practices, and healthy lifestyle habits can be an important part of managing the condition. While it won’t cure alopecia areata, it can help reduce flare-ups and support better overall well-being.

Recognising the warning signs

The most common sign of alopecia areata is hair thinning or falling out in small, round patches. Some individuals may notice tingling, itching, or a burning sensation in the affected areas before hair loss occurs. In certain cases, changes in fingernails and toenails, such as pitting, ridges, or white spots, can also accompany the condition².

Alopecia areata can also resemble other forms of hair loss, such as fungal infections, traction alopecia or even regular androgenetic alopecia especially when alopecia areata takes a more diffuse pattern. A proper medical examination and close-up trichoscopic evaluation is therefore essential for a proper diagnosis. Dermatologists usually diagnose the condition through a clinical examination, reviewing medical history, and occasionally performing a scalp biopsy or blood tests to rule out other autoimmune disorders if necessary.

Available hair loss treatments

While there’s currently no definitive cure for alopecia areata, several hair loss treatment options can help stimulate regrowth and manage symptoms. The choice of treatment depends on factors such as the extent of hair loss, age, and individual response.

1. Topical treatments

Corticosteroid creams or ointments are commonly prescribed to reduce inflammation around hair follicles. These can be applied directly to affected areas to help the follicles recover. Another option is topical immunotherapy, which uses mild chemical agents like diphencyprone (DPCP) to provoke a local allergic reaction, redirecting the immune system’s attention away from the follicles¹.

2. Injections and oral medications

For smaller bald patches, corticosteroid injections into the scalp can be highly effective. These treatments help suppress the immune attack locally and encourage regrowth. In more severe cases, oral corticosteroids or immunosuppressants like methotrexate may be prescribed, although these come with potential side effects and require close medical supervision⁴.

3. JAK Inhibitors

A newer class of drugs known as Janus kinase (JAK) inhibitors, such as baricitinib and ritlecitinib, has shown promising results in treating moderate to severe alopecia areata. These medications work by blocking specific immune pathways responsible for the autoimmune response. Studies have shown that many patients experience significant hair regrowth after several months of treatment⁶.

4. Light and laser therapy

Low-level laser therapy (LLLT) uses specific wavelengths of light to stimulate hair follicles and improve circulation in the scalp. While research is still ongoing, some individuals find it a useful complementary option to other treatments.

5. Cosmetic solutions

For those who prefer non-medical approaches, wigs, hairpieces, and scalp micropigmentation can help restore confidence and improve appearance while waiting for hair to regrow. Support groups and counselling can also provide emotional reassurance, especially for those struggling with self-esteem due to visible hair loss.

Living with alopecia areata

Alopecia areata can be unpredictable. Hair may regrow on its own or fall out again unexpectedly. This uncertainty can be emotionally challenging, but it’s important to remember that the condition doesn’t affect overall physical health. Many people live full, confident lives with alopecia, and support networks are available both online and offline for those seeking connection and advice.

Taking care of scalp health, eating a balanced diet rich in vitamins and minerals, and managing stress all play an important role in maintaining hair and immune health. Above all, consulting a dermatologist ensures that any treatment plan is tailored specifically to your needs.

Conclusion

Alopecia areata reminds us just how complex and interconnected the immune system and body truly are. When the immune system misfires and attacks the hair follicles, it can cause distressing changes to one’s appearance, but with understanding and proper care, recovery is possible.

If you’re experiencing sudden hair loss or noticing unusual bald patches, seek professional guidance early. Angeline Yong Dermatology offers comprehensive cosmetic, surgical, and medical treatments in Singapore, helping patients restore not just their hair, but also their confidence and quality of life.

References

Pratt, C., King, L., Messenger, A. et al. Alopecia areata. Nat Rev Dis Primers 3, 17011 (2017). https://doi.org/10.1038/nrdp.2017.11

Gilhar, A., Etzioni, A., & Paus, R. (2012). Alopecia areata. The New England journal of medicine, 366(16), 1515–1525. https://doi.org/10.1056/NEJMra1103442

Petukhova, L., Duvic, M., Hordinsky, M., Norris, D., Price, V., Shimomura, Y., Kim, H., Singh, P., Lee, A., Chen, W. V., Meyer, K. C., Paus, R., Jahoda, C. A., Amos, C. I., Gregersen, P. K., & Christiano, A. M. (2010). Genome-wide association study in alopecia areata implicates both innate and adaptive immunity. Nature, 466(7302), 113–117. https://doi.org/10.1038/nature09114

Hordinsky M. K. (2013). Overview of alopecia areata. The journal of investigative dermatology. Symposium proceedings, 16(1), S13–S15. https://doi.org/10.1038/jidsymp.2013.4

van der Steen, P., Boezeman, J., Duller, P., & Happle, R. (1992). Can alopecia areata be triggered by emotional stress? An uncontrolled evaluation of 178 patients with extensive hair loss. Acta dermato-venereologica, 72(4), 279–280.

Sanchez, K., Englander, H., Salloum, L., Gregoire, S., Biba, U., Ershadi, S., & Mostaghimi, A. (2025). Evaluating Current and Emergent JAK Inhibitors for Alopecia Areata: A Narrative Review. Dermatology and therapy, 15(10), 2749–2764. https://doi.org/10.1007/s13555-025-01517-9

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Alopecia Areata: Why The Immune System Attacks Hair Follicles