Female hair loss: the main causes

Main causes of female hair loss

Women often wonder why their hair starts falling out without any obvious reason. In the vast majority of cases, the answer has little to do with shampoo or the latest trendy supplement. The roots of the problem are almost always internal: hormonal or genetic.

The hereditary factor and the action of androgens

The most frequent cause of female hair loss causes is genetic. It is called female androgenetic alopecia. It affects about 40% of women by age 50, but the first signs can appear as early as after 30. Unlike what happens in men, female thinning spreads over the top of the scalp, without receding the hairline. It all revolves around a hormone called DHT, a derivative of testosterone. Due to a hereditary predisposition, follicles sensitive to this hormone miniaturize over time. With each cycle, the hair becomes thinner and shorter, until it stops growing altogether. It is not a disease, it is a chronic condition. It can be slowed down and managed, but it must be addressed consistently.

Iron deficiency and thyroid dysfunctions

Iron is also something to keep an eye on.

Looking only at hemoglobin is not enough.

I always ask for the reserves, meaning ferritin. Below 30 ng/mL, the follicle suffers. A prolonged deficiency accelerates existing thinning. Then there is the thyroid. Undiagnosed hyperthyroidism or hypothyroidism disrupts the hair cycle, pushing many follicles simultaneously into the telogen phase. The result is a massive loss 2-3 months after the imbalance. Recovery here comes when the hormone normalizes, not with lotions.

Stress, childbirth, and menopause

Telogen effluvium is the typical response to a traumatic event. A bereavement, surgery, childbirth, or even intense emotional stress. The body suspends the activity of non-essential bulbs. It can be dramatic and sudden, but in most cases it resolves within 6-9 months. Then menopause arrives. The drop in estrogen causes androgens to take over, even in women without a strong predisposition. Hair volume and texture change. It is a physiological process, yet many women come to the clinic convinced it is just fatigue.

Polycystic ovary syndrome (PCOS)

In young women, hormonal female hair loss causes are almost always linked to PCOS. The excess of androgens produced by the ovaries causes thinning, acne, and hirsutism. To rule it out, the first step is a pelvic ultrasound and hormonal tests (free testosterone, LH/FSH). Without a diagnosis, any topical treatment becomes wasted time.

The diagnosis is not made by looking at the drain in the sink. You need a dermatologist, targeted blood tests, sometimes a scalp biopsy.

Warning signs: when to worry

In women, hair loss is not always an emergency. Every day we lose between 50 and 100 hairs, it is normal. But when the number rises and patches appear, you need to stop and ask yourself what is happening.

Signs that should not be ignored

• Clumps on the pillow or in the shower, if every time you wash your hair you find about twenty in your hands, it is no longer physiological.

• The part widens, one of the classic signs of female thinning, often progressive.

• Reduced regrowth: you notice new hairs are thinner or struggle to emerge, especially on the top of the head.

• Sudden and abundant loss: in a few weeks you lose 30-40% of density. This is often telogen effluvium triggered by stress, childbirth, or high fever.

• Itching, burning, or scaling of the scalp: these symptoms can accompany inflammatory conditions like seborrheic dermatitis, which accelerates hair loss.

A 38-year-old patient told me: 'I noticed because I had to sweep the bathroom floor every day.' It is the frequency, that detail, that is the most honest alarm bell. You do not need an exact number: when the action becomes routine, it is time to investigate.

Difference between temporary and chronic hair loss

Reactive hair loss, linked to stress or seasonal change, usually stabilizes within 3-6 months. If 6-8 months pass without improvement, or you also notice fatigue, irregular cycles, or pimples, it could be due to hormones (like polycystic ovary syndrome), and that requires a check-up. In that case, it is better to schedule a visit with an endocrinologist as well as a dermatologist.

Do not wait until you see the scalp in patches. The sooner you intervene, the more chance you have of recovery. A consultation with a dermatologist (trichologist) is the first sensible step.

The role of vitamins and nutritional deficiencies

Usually, we start with iron. An iron deficiency, even without full-blown anemia, is among the most underestimated causes of hair loss in women. The mechanism? When iron stores are low, the body diverts the few resources to essential functions and reduces hair production. The result is diffuse loss, often mistaken for normal. Many women confuse diffuse thinning with stress or premature aging.

The figure to keep an eye on is not just hemoglobin, but ferritin. Below 30 ng/mL, the hair suffers, even if routine blood tests seem normal. One in four women between the ages of 30 and 50 has low ferritin and doesn't know it. And often they themselves do not suspect it.

Zinc, selenium and vitamin D

Zinc is another mineral not to be overlooked. Without it, the hair follicle cannot divide or repair itself. If the deficiency is moderate, hair falls out in clumps, becoming brittle and dull. A similar reasoning applies to vitamin D: levels below 20 ng/mL have been associated with alopecia areata and a faster-than-normal hair turnover.

Selenium is a more controversial topic. A serious deficiency slows growth; an excess, however, from do-it-yourself supplements, can become toxic. It is a fine line to walk.

NutrientWhat it does for hairSign of deficiencyFood sources IronTransports oxygen to the follicleDiffuse thinning, fatigueRed meat, legumes, spinach ZincRepairs and grows the follicleHair loss in clumps, dandruffOysters, pumpkin seeds, eggs Vitamin DRegulates the follicle cycleAlopecia areata, seasonal sheddingFatty fish, sunlight, mushrooms Vitamin B12Produces red blood cells (oxygen)Anemia, brittle hairMeat, dairy, eggs

The role of restrictive diets

Drastic weight loss diets, especially those that eliminate carbohydrates or fats, cause multiple deficiencies.

Underlying diseases that cause hair loss

When a woman starts losing hair, she immediately thinks of hormones, stress or genetics. Another category of causes to consider concerns underlying diseases. Often, hair is the first to signal that something in the body is not working.

Among the most common conditions is the thyroid. Both hypothyroidism and hyperthyroidism can trigger diffuse hair loss. Hair becomes dry and brittle, and the growth cycle slows down. In my experience, many women discover their thyroid problem precisely because their hair thins. A simple blood test with TSH and FT4 provides clarity.

Iron deficiency anemia is another frequent cause. Ferritin below 30 ng/mL? The follicles slow down production. Often without obvious symptoms, about 15% of women of childbearing age have low iron stores. With targeted supplementation under medical supervision, the trend reverses in 3-6 months.

Another frequent cause is polycystic ovary syndrome (PCOS). It affects 5-10% of women. Excess androgens lead to thinning on the crown of the head, with a pattern similar to male pattern baldness. It is often accompanied by acne, excessive hair growth or irregular cycles. A gynecological visit with ultrasound and hormone testing is the best way to diagnose it.

Alopecia areata is an autoimmune disease. The patches are round, smooth, without inflammation. It can appear at any age and in some cases regresses spontaneously. In extensive cases, targeted dermatological treatment is needed.

Other autoimmune diseases, such as systemic lupus erythematosus or sarcoidosis, can also cause hair loss. It is usually temporary: it improves once the underlying disease is under control.

A mention should also be made of telogen effluvium. It is a reaction to physical stress, a serious infection, surgery, or childbirth. Hair loss begins 2-3 months after the triggering event and usually resolves on its own within six months.

When discussing female hair loss causes, looking beyond the surface is the first step. Unexplained hair loss deserves a complete check-up: complete blood count, ferritin, TSH, vitamin D, plus a thorough dermatological evaluation.

Remedies and treatments: how to stop hair loss

When discussing female hair loss causes, the possible solutions are as many as the triggering factors. Stopping thinning requires a targeted approach, not a miracle product. About 40% of women under 50 notice progressive thinning, and the best response comes only after understanding what causes it.

Let's start with the basics. A diet poor in iron, protein and zinc is among the most underestimated causes. If the loss is diffuse and not localized, first check your ferritin levels. Below 40 ng/mL the impact is already noticeable. Iron, vitamin D and biotin: supplementing them only makes sense if there is a real deficiency. Taking supplements randomly is not very helpful.

Then there is stress, it is not a trivial excuse.

Topical and pharmacological treatments

Minoxidil is still the first-line drug in the guidelines. For women, it is used at 2% or 5%, once a day. A 3-month bottle costs between 35 and 50 € at the pharmacy. It gives the best results on the crown: after six months, a 20-30% increase in anagen-phase hairs is recorded. Mild flaking is the most common side effect, but it disappears in about a week. Those who cannot tolerate minoxidil can try spironolactone, an antiandrogen used off‑label: at 50‑100 mg per day it reduces hormonal hair loss in about 60% of patients. A 42-year-old patient with diffuse thinning for 8 months presented to the DermaGroup Milan clinic in 2024. Ferritin at 18 ng/mL, low vitamin D. With targeted supplementation plus minoxidil at 2%, she recovered 70% of her volume in 6 months.

Instrumental therapies and outpatient procedures

If the response to topical treatments is modest, in-office treatments are considered. Platelet-rich plasma (PRP) involves injections every 4-6 weeks. The cost is 200-350 € per session and at least 3-4 sessions are needed. Results are visible after 4-5 months and last about a year. Low-level laser therapy (LLLT) is used at home with caps costing 300 to 800 euros. Studies on 50 patients report an 18% increase in density after 24 weeks. Microagopuncture (microneedling), alone or combined with minoxidil, costs about 100-150 euros per session, and initially 3 sessions are needed. In the table below you will find a comparison of the three most common options.

TherapyCost per sessionSessionsEfficacy (after 6 months) Down-time PRP200-350 €3-4+25-35% density24 h (redness) LLLT300-800 € (one-time purchase) At-home, 3-4/week+15-20% densityNone Microneedling100-150 €3 + maintenance+20-30% (in combination)12 h (mild redness)

• Always check ferritin before undergoing PRP: below 40 ng/mL, results decrease by 40%.

• During topical therapy, avoid aggressive treatments such as alcohol-based packs, because they dry out the scalp and reduce absorption.

• Do not change the brand of minoxidil mid-treatment: the vehicle base can alter penetration.

• If you take spironolactone, check your blood pressure every 4-6 weeks: in 1 out of 8 patients it causes transient hypotension.

What does it mean when you lose too much hair?

Excessive hair loss can indicate an underlying problem such as stress, hormonal imbalances, nutritional deficiencies, or medical conditions like alopecia. It is normal to lose 50-100 hairs per day, but if you notice patches or diffuse thinning, it is advisable to consult a dermatologist for an accurate diagnosis.