Hair loss can be frustrating, distressing, and confusing—especially when you’re not sure why it’s happening. Whether you’re noticing gradual thinning, sudden shedding, or patchy bald spots, the first step toward effective treatment is understanding the underlying causes of hair loss.
There isn’t a one-size-fits-all answer. Hair loss can result from genetic factors, hormonal shifts, autoimmune conditions, nutritional deficiencies, or stress-related responses like telogen effluvium. Some experience temporary shedding, while others face progressive thinning that requires long-term care.
If you’ve been wondering, “why is my hair falling out?”, this guide breaks down the most common—and often overlooked—reasons behind hair loss in both men and women, backed by medical insights and real-world trends.
Quick Insights: Causes of Hair Loss
- The causes of hair loss range from genetics and hormones to stress, medications, and autoimmune disease.
- Asking “why is my hair falling out?” requires a multi-layered approach—no single test or assumption will explain it all.
- Hair loss causes in women often include hormone fluctuations, iron deficiency, and traction from styling.
- Telogen effluvium causes include physical or emotional stress, illness, and rapid weight loss.
- Alopecia areata causes are linked to immune system dysfunction and may come on suddenly.
- Nutrient deficiency hair loss is often reversible with targeted dietary support.
- Hormonal hair loss can affect both genders but is especially common in women during menopause or with PCOS.
- Traction alopecia is entirely preventable—early awareness is critical.
- Autoimmune hair loss and scarring types require early diagnosis and specialist care to avoid permanent damage.
Genetic and Hormonal Causes
The most common form of hair loss is genetic hair loss, also called androgenetic alopecia. This affects both men and women, though the patterns may differ.
Genetic Hair Loss (Androgenetic Alopecia)
- In men, it typically shows as a receding hairline or bald spot at the crown.
- In women, it presents as overall thinning, especially on the top of the scalp.
Dr. Ahmet Murat explains:
“We see many patients who assume their hair loss is stress-related, but in over 60% of cases, it’s hereditary. The earlier it’s diagnosed, the better it can be managed.”
Hormonal Hair Loss
Hormonal imbalances can also cause significant shedding or thinning. This includes:
- Thyroid disorders (hypo or hyperthyroidism)
- Polycystic ovary syndrome (PCOS)
- Menopause-related estrogen drop
- High levels of dihydrotestosterone (DHT) in both genders
Which hormone causes hair loss in females?
The most common hormone responsible for female hair loss is DHT (dihydrotestosterone). Elevated androgen levels, often due to PCOS or menopause, can shrink hair follicles and shorten growth cycles.
Hormonal hair loss is usually diffuse and gradual. Blood tests can confirm the presence of an imbalance.
Autoimmune and Scarring Hair Loss Types
Some types of hair loss are triggered by the body’s immune system mistakenly attacking hair follicles. These are classified as autoimmune hair loss conditions and often present differently from genetic thinning.
Alopecia Areata
This condition leads to sudden, patchy hair loss, often seen as coin-sized bald spots. In some cases, it may progress to complete scalp (alopecia totalis) or full-body hair loss (alopecia universalis).
- It affects both men and women, typically before age 40.
- Stress, viral infections, or genetics may act as triggers.
- Hair may regrow spontaneously, though relapses are common.
Dr. Ahmet Murat notes:
“Alopecia areata is unpredictable. That’s why we always perform immune-related blood tests and suggest corticosteroid or immunotherapy-based options depending on the severity.”
What illness causes hair loss?
Alopecia areata, lupus, thyroid disease, and certain autoimmune disorders like lichen planopilaris or frontal fibrosing alopecia can all cause hair loss by inflaming or damaging hair follicles.
Frontal Fibrosing Alopecia & Other Scarring Types
This type of hair loss causes permanent follicle destruction and scarring on the scalp.
- More common in postmenopausal women
- Leads to a receding hairline or loss of eyebrows
- Requires early diagnosis to prevent irreversible damage
Autoimmune and scarring forms often need a scalp biopsy to confirm and require early treatment to halt progression.
Telogen Effluvium and Stress-Triggered Hair Loss
One of the most overlooked but widespread forms of hair shedding is telogen effluvium. It occurs when a sudden stressor pushes more hair follicles than usual into the resting (telogen) phase, causing noticeable shedding a few weeks or months later.
Common telogen effluvium causes include:
- Major surgery or physical trauma
- High fever or severe illness (e.g., COVID-19)
- Childbirth (postpartum shedding)
- Crash diets or rapid weight loss
- Emotional stress or psychological burnout
This condition is typically temporary, lasting 3–6 months, and doesn’t involve permanent follicle damage.
Dr. Ahmet Murat comments:
“Telogen effluvium is very common in patients who’ve gone through a health crisis or emotional shock. We don’t rush into transplants here. Our focus is on stabilizing the body and encouraging regrowth through nutritional and stress-management support.”
What illness causes hair loss?
Illnesses like high fevers, COVID-19, thyroid disorders, and infections can cause telogen effluvium, a temporary form of hair loss that appears several weeks after the triggering event.
Hair typically regrows within months once the stressor is resolved, but chronic telogen effluvium may require deeper investigation.
Discover More About Hair Transplants
Nutritional and Deficiency-Related Hair Loss
Diet plays a vital role in hair health. When the body lacks key nutrients, it prioritizes vital organs—leaving hair follicles with less support. This results in nutrient deficiency hair loss, often seen as general thinning rather than patchy baldness.
Most common deficiencies linked to hair loss:
- Iron – particularly common in women with heavy periods or low meat intake
- Vitamin D – impacts follicle cycling and immune regulation
- Zinc – important for follicle repair and DNA synthesis
- Biotin (Vitamin B7) – frequently marketed, but true deficiency is rare
- Protein – crash diets and eating disorders can lead to rapid thinning
Dr. Ahmet Murat explains:
“Before considering surgical treatment, we always check ferritin, Vitamin D, B12, and thyroid levels. Sometimes, correcting these deficiencies alone leads to significant regrowth.”
Which vitamin deficiency causes hair loss?
Vitamin D and iron deficiency are the most common nutritional causes of hair loss. Low levels affect follicle strength and growth cycles, particularly in women.
What deficiency causes hair loss?
Iron, zinc, and protein deficiencies are top contributors. Blood tests can confirm these levels, and supplementation often improves hair density within months.
This type of hair loss is often reversible once the deficiency is corrected, though regrowth can take 3–6 months.
Traction Alopecia and Mechanical Causes
Traction alopecia is caused by repeated tension or friction on the hair follicles. Over time, this can lead to weakened roots, inflammation, and even permanent hair loss if not addressed early.
Common habits that cause traction-related damage:
- Tight ponytails, buns, or braids worn frequently
- Hair extensions or weaves
- Headwear that rubs the same scalp area
- Constant pulling, brushing, or use of harsh clips
This form of hair loss is especially common in certain cultural hairstyles, athletes wearing tight headgear, and individuals who style their hair aggressively.
Dr. Ahmet Murat advises:
“Traction alopecia is 100% preventable. Once diagnosed, we recommend avoiding the triggering hairstyles and, if needed, use regenerative techniques like PRP or low-level laser therapy.”
The damage is usually reversible in early stages, but long-term traction may lead to scarring and permanent follicle loss.
Medical Treatments, Drugs, and Chemotherapy
Certain medications and medical treatments can cause temporary or permanent hair loss as a side effect. This type of shedding often begins weeks after starting the drug and may reverse after stopping it—though not always.
Common medications that cause hair loss:
- Chemotherapy agents (e.g., doxorubicin, cyclophosphamide, paclitaxel)
- Blood pressure medications (beta-blockers, ACE inhibitors)
- Antidepressants (SSRIs, tricyclics)
- Retinoids (used for acne or psoriasis)
- Antithyroid drugs and anticoagulants
Dr. Ahmet Murat comments:
“When reviewing a patient’s history, we don’t just look at hair—we review their prescription list. Drug-induced shedding can mimic other types and requires different treatment timelines.”
What chemo causes hair loss?
Chemotherapy drugs like paclitaxel, cyclophosphamide, and doxorubicin are known to cause hair loss by attacking rapidly dividing cells, including hair follicles.
What illness causes hair loss?
In addition to autoimmune diseases, illnesses treated with chemotherapy—like cancer—can result in hair loss due to the toxicity of the treatment.
Hair often regrows within 3–6 months after discontinuing the drug, though texture and density may change temporarily.
Diagnosis: How to Identify the Cause of Hair Loss
Pinpointing the cause of hair loss is the most important step toward effective treatment. Because symptoms can overlap, accurate diagnosis requires a combination of clinical examination, medical history, and lab testing.
Common diagnostic tools:
- Pull test: Helps assess active shedding levels
- Trichoscopy: Microscopic examination of scalp and follicles
- Scalp biopsy: Used for suspected autoimmune or scarring alopecia
- Blood tests: To evaluate nutrient levels, thyroid function, hormone balance (Ferritin (iron storage), Vitamin D and B12, TSH (thyroid-stimulating hormone), Androgen levels (DHEA, testosterone))
Dr. Ahmet Murat explains:
“We never rush into treatment without a full evaluation. A patient may assume it’s stress, but it turns out to be iron deficiency or early scarring alopecia. Diagnosis is where success begins.”
The diagnosis phase determines not just the cause, but also the severity, potential for reversal, and the most effective treatment path.
Prevention and Treatment Matching by Cause
Once the cause of hair loss is confirmed, treatment can be customized for long-term success. While not all types of hair loss are reversible, many can be significantly improved with timely intervention.
Treatment by cause:
Genetic hair loss:
- FDA-approved: minoxidil (topical), finasteride (oral – men only)
- Hair transplant for advanced cases
- PRP (Platelet-Rich Plasma) as a regenerative boost
Hormonal hair loss:
- Address underlying issues (PCOS, thyroid disorders)
- Hormone-regulating treatments or oral contraceptives (women)
Autoimmune hair loss (e.g., alopecia areata):
- Corticosteroid injections or topical immunotherapy
- JAK inhibitors for resistant cases
- Monitoring stress and immune triggers
Telogen effluvium:
- Identify and resolve the stressor (illness, diet, trauma)
- Support recovery with biotin, iron, and Vitamin D
- Avoid unnecessary treatments—focus on patience
Nutritional deficiency:
- Blood-test-guided supplements (iron, zinc, D, B12, protein)
- Adjust dietary habits for long-term follicle health
Traction or mechanical loss:
- Immediate change of styling practices
- Early intervention may reverse loss; late-stage may need grafting
Medication-induced loss:
- Adjust or replace medication if possible (under physician guidance)
- Cosmetic options or support therapies during chemo or chronic illness
Dr. Ahmet Murat concludes:
“Effective hair loss treatment isn’t about trial and error. It’s about matching the exact cause to the right protocol—whether that’s medical, nutritional, or surgical. That’s how we get results.”
Hair Loss Statistics & Trends You Should Know
- About 85% of men and 33% of women will experience noticeable hair loss at some point in their lives.
- Androgenetic alopecia is responsible for about 95% of male hair loss cases. It also affects ~50% of men by age 50 and ~25% of women by the same age.
- Alopecia areata affects approximately 0.1–0.2% of people at any given time, with a 2% lifetime incidence globally.
- Worldwide, around 160 million people are affected by alopecia areata.
- In a large dermatology survey, 73% of cases were non-scarring alopecias, while 27% were scarring types.
- Women report more mild hair thinning (46.8%) than men (34.1%), but men more often experience severe hair loss (12.5% vs 10.7%).
- Post‑menopausal women have significantly higher risk of moderate to severe hair loss (13.7%) compared to younger women (9.8%).
- Telogen effluvium is now recognized as a frequent stress-related hair loss trigger, increasingly linked to illness (e.g. COVID‑19), postpartum changes, and crash dieting.
- Traction alopecia is prevalent among those using tight hairstyles and specific headgear—common in athletic, cultural, or stylistic settings.
- Hair loss treatments industry was valued at $8.85 billion in 2024, reflecting growing demand for medical, nutritional, and lifestyle interventions.
Important Questions & Answers
What are the most common causes of hair loss?
The most common causes of hair loss include genetic hair loss (androgenetic alopecia), hormonal imbalances, nutrient deficiencies, autoimmune diseases like alopecia areata, and stress-related conditions such as telogen effluvium. Other factors include medications, scalp infections, and tight hairstyles. Accurate diagnosis is key to effective treatment.
Why is my hair falling out suddenly?
Sudden hair shedding may be due to telogen effluvium, which is often triggered by illness, stress, surgery, or nutritional deficiency. It can also result from medication changes or postpartum hormonal shifts. If the shedding lasts longer than three months, a clinical evaluation is recommended to identify the cause.
Which vitamin deficiency causes hair loss?
Vitamin D deficiency is strongly linked to hair thinning, especially in women. Iron and zinc deficiencies also contribute to diffuse hair loss. Blood testing helps confirm these deficiencies, and correcting them often results in noticeable regrowth within 3–6 months.
Which hormone causes hair loss in females?
The main hormone responsible for female hair loss is DHT (dihydrotestosterone), a byproduct of testosterone. In women, high androgen levels—often due to PCOS or menopause—can shrink hair follicles, leading to thinning on the top and sides of the scalp.
What deficiency causes hair loss in women?
Iron deficiency is one of the leading causes of hair loss in women. Other common deficiencies include Vitamin D, zinc, and protein. These nutrients are vital for healthy follicle function. Addressing these deficiencies often leads to improved hair density and reduced shedding.
What chemo causes hair loss?
Chemotherapy drugs like doxorubicin, cyclophosphamide, and paclitaxel commonly cause hair loss. They target rapidly dividing cells, including hair follicles. Hair usually begins to fall out within 2–4 weeks of starting treatment and regrows after chemotherapy ends, though texture and density may change.
What illness causes hair loss?
Hair loss can result from illnesses such as autoimmune conditions (e.g., alopecia areata, lupus), thyroid disease, COVID-19, and infections causing high fever. These can trigger temporary or permanent shedding, depending on the disease’s severity and duration.
How can I tell if my hair loss is hormonal or genetic?
Genetic hair loss tends to follow a predictable pattern—receding hairline or crown thinning in men, diffuse thinning in women. Hormonal hair loss is more variable and often linked to life stages like pregnancy or menopause. Blood tests and scalp exams help distinguish the type.
Can stress cause hair loss even without illness?
Yes. Emotional or psychological stress can trigger telogen effluvium, a temporary hair loss condition where more hairs than normal enter the resting phase. It often occurs 6–12 weeks after the stress event and resolves once the underlying trigger is addressed.
Is hair loss from nutrient deficiency reversible?
In many cases, yes. If caught early, nutrient deficiency hair loss caused by low iron, zinc, protein, or vitamins can be reversed with targeted supplementation and diet changes. Regrowth typically begins within 8–12 weeks, but full recovery may take several months.
Ready for Answers That Work?
At Hermest Hair Clinic, we don’t guess. We diagnose. Whether you’re dealing with hormonal shifts, immune-related thinning, or sudden shedding, our team performs a comprehensive evaluation to uncover the real cause—and guide you toward the most effective solution.
Book your expert consultation today and let us help you treat the root, not just the symptoms.