Alopecia is the medical term for hair loss from any part of the body. It ranges from small, coin-sized patches on the scalp to complete loss of all body hair, and it can be temporary or permanent depending on the type. Around 50 to 100 hairs naturally fall out each day as part of the normal growth cycle, but alopecia refers to hair loss that goes well beyond that baseline.
How Hair Normally Grows and Falls Out
Hair grows in a repeating cycle with three phases. The growing phase (anagen) lasts two to six years, which is why scalp hair can get so long. A brief transitional phase follows for about three weeks as the hair detaches from its blood supply. Then comes a resting phase lasting two to three months, after which the hair falls out and a new one begins growing in the same follicle.
Different types of alopecia disrupt different parts of this cycle. Some cause large numbers of hairs to enter the resting phase all at once, leading to sudden, widespread thinning. Others shorten the growing phase dramatically, so hairs never reach their full length. And in the most severe forms, the follicle itself is destroyed, making regrowth impossible.
The Main Types of Alopecia
Hair loss falls into two broad categories: nonscarring (where the follicle stays intact) and scarring (where the follicle is permanently destroyed). Nonscarring types are far more common.
Androgenetic Alopecia (Pattern Baldness)
This is the most familiar type, often called male-pattern or female-pattern hair loss. It develops after puberty and progresses gradually over years or decades. In men, it typically starts with a receding hairline and thinning at the crown. In women, it usually appears as overall thinning across the top of the scalp while the hairline stays intact. Genetics play a strong role, though no single gene has been identified as the cause. Hormonal sensitivity in the hair follicles drives the gradual miniaturization of hairs until they become fine, short, and eventually stop growing altogether.
Alopecia Areata (Autoimmune)
In alopecia areata, the immune system mistakenly attacks hair follicles, causing inflammation that disrupts the growing phase. It typically shows up as one or more smooth, round bald patches on the scalp, though it can affect any area with hair. The lifetime prevalence is roughly 0.1% of the global population, with slightly higher rates in men than women. Both children and adults can develop it.
People with other autoimmune conditions like thyroid disease, vitiligo, or psoriasis face a higher risk. Allergic conditions such as hay fever and eczema also increase susceptibility. Emotional stress or illness may trigger flares in people who are already predisposed, but most cases have no obvious trigger. Genetics play a role: scientists have linked multiple genes involved in immune function to the disease, and having a close family member with it raises your risk.
In more severe forms, alopecia areata can progress to alopecia totalis, which is complete loss of all scalp hair, or alopecia universalis, where all body hair is lost, including eyebrows, eyelashes, and body hair.
Telogen Effluvium
This is a temporary but often alarming type of hair loss where significantly more than the normal 100 hairs per day shift into the resting phase and fall out. Common triggers include childbirth, major surgery, severe illness, rapid weight loss, and extreme stress. The shedding usually starts two to three months after the triggering event and resolves on its own once the cause is addressed.
Scarring Alopecia
In scarring (cicatricial) alopecias, inflammation destroys the stem cells in the hair follicle, replacing them with scar tissue. The two most common forms are frontal fibrosing alopecia and lichen planopilaris, both characterized by inflamed follicles surrounding areas of permanent hair loss. Because the follicles are gone, hair cannot regrow in scarred areas, making early diagnosis and treatment critical to prevent further spread.
Other Types
Traction alopecia results from prolonged pulling on the hair from tight hairstyles like braids, ponytails, or extensions. Anagen effluvium is rapid hair loss during the growing phase, most commonly caused by chemotherapy. Trichotillomania is a condition where a person compulsively pulls out their own hair.
How Alopecia Is Diagnosed
A dermatologist can often identify the type of hair loss through a physical exam and your medical history. One common in-office test is the pull test, where the doctor gently tugs on a small section of hair to see how many strands come out easily. Trichoscopy, a technique using a specialized magnifying device to examine the scalp and hair follicles in detail, helps identify specific patterns that point to different types of alopecia. In uncertain cases, a small scalp biopsy can confirm the diagnosis, particularly when scarring alopecia is suspected.
Treatment Options for Pattern Baldness
For androgenetic alopecia, the most widely used topical treatment is minoxidil, available in 2% and 5% solutions and foams. It needs to be applied once or twice daily, and you can expect to see new growth within four to eight months if it’s working. Results stabilize after 12 to 18 months of consistent use. The catch: if you stop using it, the hair loss resumes.
Oral medications that block the hormone responsible for shrinking follicles are another option, primarily for men. These also require ongoing use. For women with pattern hair loss, different hormonal approaches are available.
Hair transplant surgery moves follicles from a donor area (usually the back of the head, where hair is resistant to thinning) to balding areas. The two main techniques are follicular unit transplantation, which removes a strip of scalp tissue, and follicular unit excision, which harvests individual follicle groups one by one. FUE has become the more popular option among patients, though both approaches have strengths depending on the extent of hair loss and donor hair availability.
Treatment for Alopecia Areata
The encouraging news about alopecia areata is that the follicles are not permanently damaged. Between 34% and 50% of people with patchy hair loss experience spontaneous regrowth within one year without any treatment. Because of this, some people choose to wait and see before starting medication.
For those who do seek treatment, corticosteroid injections into the bald patches have long been a standard approach. But the biggest recent advance has been a class of oral medications called JAK inhibitors, which work by calming the immune system’s attack on hair follicles. Three have received FDA approval in rapid succession: baricitinib was approved in June 2022 for adults with severe alopecia areata, with 35 to 40% of patients in clinical trials achieving at least 80% scalp hair coverage by 36 weeks. Ritlecitinib followed in June 2023 and is approved for patients 12 and older, with results that continued improving over time: 32% had significant regrowth by 24 weeks, rising to 61% at two years. A third option, deuruxolitinib, was approved in July 2024, with 41% of trial participants achieving at least 80% scalp coverage by 24 weeks.
These medications represent a meaningful shift for people with severe alopecia areata, who previously had limited options. They do require ongoing use, and like all immune-modifying drugs, they come with potential side effects that need to be weighed against the benefits.
The Emotional Side of Hair Loss
Hair loss affects more than appearance. For many people, particularly those with alopecia areata that strikes suddenly and unpredictably, the psychological impact can be significant. Children and teenagers may face social challenges, and adults often report anxiety about the uncertainty of whether and when hair will return. Support groups, both online and in person, can help. The fact that alopecia areata preserves the follicles, keeping the door open for regrowth, is something many people find genuinely reassuring as they navigate treatment decisions.