When you’re diagnosed with a chronic health condition like alopecia areata, it’s natural to wonder why this happened to you. While there are many factors that can affect your risk, your immune system is ultimately responsible. People with alopecia areata experience patchy hair loss when the immune system attacks their hair follicles.

This article will cover how and why the immune system attacks the hair follicles in people with alopecia areata. We’ll also cover other factors that raise your risk of alopecia areata and which treatment options target the immune response. For more information about your treatment options, talk with your dermatologist.

How Does the Immune System Cause Hair Loss?

When you were diagnosed with alopecia areata, your healthcare provider may have mentioned that the condition is considered an autoimmune disorder, which means that it’s related to your immune system. Your immune system usually protects you from infection and harmful germs. This system is responsible for fighting invaders and helping you heal from sickness or injury.

An autoimmune condition occurs when the immune system mistakes healthy cells in the body for foreign invaders and attacks them. Common examples of autoimmune conditions include rheumatoid arthritis and lupus. You may be surprised to learn that your hair loss comes from an immune system attack. Autoimmune conditions like alopecia areata are chronic. They can be managed with treatment, but there is no cure available.

When you have alopecia areata, your immune system malfunctions and recognizes normal hair follicles as invaders. The hair follicles are pores that surround the root of the hair strands and produce the hair strand. When the immune system attacks the hair follicles, hair stops growing. The immune system may also attack the nails.

When the immune system attacks the hair follicles, you’ll notice patchy hair loss on your scalp, face, or body. Your eyebrows or eyelashes may also fall out. When your immune system attacks your nails, you may find that they feel weaker. It’s common to experience nail thinning or splitting. You may also see tiny white spots or dents on the nails.

Healthcare providers are not sure why the immune system targets the hair follicles. Fortunately, the damage to the hair follicles isn’t permanent, which means that the hair can regrow in the future. Alopecia areata isn’t contagious.

Why Does the Hair Fall Out in Patches?

Alopecia areata usually causes the hair to fall out in small, round patches. These patches are often around the size of a quarter. It’s also possible to experience more severe hair loss. The hair loss usually continues for a few weeks, then starts to grow back after several months.

Alopecia areata causes patchy hair loss because of how it affects the hair follicle’s growth cycle. Hair growth occurs in three phases. During the first phase, hair strands actively grow. In the second phase, the root of the hair shaft hardens, and in the third phase, this hardened root sits in the hair follicle until a new hair strand grows. Once a new follicle has formed and the new hair is actively growing, the old strand will fall out.

When the immune system attacks the hair follicles, it causes inflammation. This inflammation causes the active growth phase to pause. When the hair follicles cannot continue in the active growth phase, they revert to the other phases when the hair is getting ready to fall out.

Alopecia areata affects the hair follicles in a “bee swarm” pattern. The immune cells surround and attack individual hair follicles in one or a few locations, rather than the entire scalp at once. This is why the hair falls out in round patches. Because each strand of hair is on its own growth schedule, they’re affected differently.

Other Factors Associated With Hair Loss in Alopecia Areata

There are several factors that can trigger alopecia areata, and researchers aren’t certain why some people experience these factors while others don’t. In addition to the immune system malfunctioning, changes in the genes may put you at risk.

Genes that regulate the body’s immune response may put you at risk of alopecia areata. Genes are made up of DNA, and they control how a cell functions and which proteins it makes.

Many of the genes that may predispose you to alopecia areata are in a gene family called the human leukocyte antigen (HLA) complex. The HLA complex helps the immune system determine which proteins are safe and which ones are foreign invaders. Changes or variations in certain HLA genes may cause the immune system to mistake the hair follicles for invaders. Changes in other genes, such as those involved in inflammation, may also contribute to your alopecia areata risk.

Having a close family member, such as a sibling or parent, with alopecia areata might make you more likely to develop it. People with other types of autoimmune conditions may be at an increased risk of alopecia. At the same time, people with alopecia areata are more at risk of developing other autoimmune conditions, including allergic asthma and certain thyroid disorders. Talk with your healthcare provider if you are concerned about your risk.

Hair loss from alopecia areata can be unpredictable. Your hair may regrow on its own and never fall out again, or you could experience frequent episodes of hair loss. It’s possible that certain lifestyle or environmental factors could trigger hair loss in people with alopecia areata. Possible triggers include:

• Stress
• Illness
• Physical injury
• Smoking

Fortunately, there are treatment options available. Talk with your dermatologist to learn more.

Are There Treatment Options That Target the Immune System?

In recent years, the U.S. Food and Drug Administration (FDA) has approved new drugs to treat alopecia areata. Many of these medications reduce the immune system’s attack on the hair follicles and lower inflammation.

Janus kinase (JAK) inhibitors are immunomodulatory drugs that can change the immune system’s activity. They work by targeting the part of the immune system that is overactive. JAK inhibitors block the immune system pathway that triggers an overreaction to the hair follicles. Taking a JAK inhibitor may reduce inflammation in the hair follicles, allowing the hair strands to keep growing.

Immunomodulatory drugs like JAK inhibitors are already used for other autoimmune conditions like vitiligo and eczema. At this time, JAK inhibitors are considered first-line treatment for people with severe alopecia that affects most of their scalp. Adding them to your treatment plan may give you 50 percent or more hair regrowth. They may also be effective at regrowing eyebrows and eyelashes.

If you believe you could be a candidate for a JAK inhibitor, talk with your dermatologist. FDA-approved JAK inhibitors for alopecia areata include baricitinib (Olumiant), ritlecitinib (Litfulo), and deuruxolitinib (Leqselvi).

Other treatment options that target the immune system’s attack on the hair follicles include:

• Methotrexate — An immunosuppressant that lowers inflammation
• Cyclosporine — An immunosuppressant that reduces the immune system’s response
• Pulse corticosteroids — High doses of steroids given to reduce inflammation

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