Hair Loss in Women: Causes, Diagnosis, and Treatment Options

The two main causes of hair loss in women are telogen effluvium and female pattern hair loss.

Telogen effluvium

Telogen effluvium is characterized by an increase in the number of hairs that prematurely enter the telogen phase of the hair follicle cycle, followed by diffuse hair shedding.

It may occur several months after a trigger such as: - fever or a significant infection; - surgery; - childbirth; - significant physiological stress; - rapid weight loss or insufficient calorie intake; - certain medications; - iron deficiency or other nutritional disorders, when present.

A characteristic feature is the relatively sudden onset of diffuse hair shedding without a clearly defined area of baldness. In many cases, hair density may recover after the trigger is addressed, but the process is slow because the hair follicle cycle takes place over several months.

Female pattern hair loss

Female pattern hair loss, also known as female androgenetic alopecia, is a progressive condition in which susceptible follicles produce increasingly thinner and shorter hairs through a process of follicular miniaturization.

Typical manifestations include:

- progressive widening of the central part; - reduced hair density in the frontoparietal region; - thinning of the hair shafts; - sometimes, reduced overall hair density across the scalp.

The condition has a significant genetic component and may be influenced by hormonal factors. Women with female pattern hair loss do not necessarily have elevated androgen levels. However, when hirsutism, recent-onset acne, irregular menstrual cycles, or other signs of hyperandrogenism are present, an endocrinological assessment may be indicated.

Other causes

Not every case of diffuse hair loss is telogen effluvium or female pattern hair loss. Depending on the manifestations, the dermatologist may also consider alopecia areata, thyroid disorders, iron deficiency, medication effects, trichotillomania, or various forms of scarring alopecia.

The presence of redness, substantial scaling, pain, a burning sensation, intense itching, pustules, or areas where the follicular openings appear to be disappearing may suggest an inflammatory scalp condition and requires dermatological assessment. Early diagnosis is particularly important in scarring alopecias because destruction of the hair follicle may be permanent.

Diagnosis begins with a careful medical history. The dermatologist will assess when the hair loss began, how quickly it has progressed, and how it is distributed, and will ask about events in the preceding months, including febrile illnesses, surgery, childbirth, significant changes in weight, restrictive diets, medications, or hormonal changes.

Examining the scalp can provide essential information. Trichoscopy allows direct assessment of the hair shafts and scalp structures and may reveal, for example, the variation in hair shaft diameter that is characteristic of miniaturization in female pattern hair loss, or changes suggestive of other conditions.

Laboratory tests are not the same for every patient. They are recommended based on the medical history and clinical examination. In cases of diffuse hair loss without an obvious cause, iron status and thyroid function may be investigated, among other factors; if signs of hyperandrogenism are present, hormonal testing may become relevant.

In selected situations, when the diagnosis cannot be established clinically and through trichoscopy, or when scarring or inflammatory alopecia is suspected, a scalp biopsy may be necessary.

Treatment depends on the identified cause.

In telogen effluvium, the first objective is to identify and address the trigger. For example, if there is severe calorie restriction, significant weight loss, or a documented deficiency, these issues should be corrected. Taking supplements empirically without an identified medical indication is not recommended.

For female pattern hair loss, topical minoxidil has the most consistent supporting evidence and is frequently recommended as first-line therapy. Its effect is not immediate: assessing the response generally requires several months of continuous treatment. A temporary increase in shedding may occur at the start of treatment, and the effect achieved is maintained for as long as treatment is continued.

Depending on the patient, the dermatologist may also consider systemic treatments such as spironolactone or other off-label therapies, including low-dose oral minoxidil. The choice depends on age, hormonal status, comorbidities, concomitant medication, and the risk of adverse effects. Oral minoxidil and antiandrogen therapies require medical assessment and are not suitable for every patient.

There are also adjunctive therapies such as PRP, microneedling, or low-level light devices. Data suggest a possible benefit in certain cases, but the level of evidence and protocols vary, and these procedures should not replace medical treatment when it is indicated.

An important principle is that treatment must be tailored to the diagnosis. A treatment that is effective for female pattern hair loss is not automatically the appropriate treatment for telogen effluvium or inflammatory alopecia.