Hair loss, or alopecia, affects millions of people worldwide — and it’s often more than just a cosmetic concern. Whether it starts as thinning around the crown or clumps falling out in the shower, understanding the causes of hair loss is the first step toward effective treatment.

There’s no single reason for shedding hair. It can be linked to genetics, stress, nutrition, autoimmune diseases, or even how you style your hair. In this guide, you’ll learn exactly what may be causing your hair loss — including under-recognized triggers like frictional damage, Demodex folliculorum, and environmental toxins — and how to address them.

Key Takeaways: Causes of Hair Loss

• Genetic factors like androgenetic alopecia are the most common causes of hair loss in both men and women.
• Medical conditions such as thyroid disorders, anemia, and autoimmune diseases can trigger significant shedding.
• Stress, poor diet, and hormonal changes often lead to temporary hair loss like telogen effluvium.
• Medications and treatments, including chemotherapy, can result in short-term or long-term hair loss.
• Hairstyling habits and scalp infections contribute to localized or patchy hair thinning if not addressed early.
• Identifying the root cause is key to choosing the right treatment and achieving long-term results.

What causes hair loss?

Hair loss can be caused by genetics, hormonal changes, autoimmune diseases, nutritional deficiencies, medications, or chronic stress. The most common type is androgenetic alopecia, which is inherited and triggered by sensitivity to DHT. Other factors include thyroid disorders, iron or vitamin D deficiency, post-pregnancy hormonal shifts, and side effects of treatments like chemotherapy. Identifying the cause is key to choosing the right treatment.

Genetic & Hormonal Causes

Androgenetic Alopecia: The Hereditary Factor

One of the most common hair loss causes in men and women is androgenetic alopecia. It’s hereditary and related to increased sensitivity to DHT (dihydrotestosterone)—a derivative of testosterone. This hormone binds to hair follicles and shortens their growth cycle, leading to gradual miniaturization and permanent hair thinning.

In men, this condition is often referred to as male pattern baldness, while in women it’s known as female pattern hair loss.

Key Differences in Men vs. Women

• Men usually experience a receding hairline and thinning at the crown. The Norwood Scale is used to classify the extent.
• Women tend to have diffuse thinning on the top of the scalp while retaining the frontal hairline. The Ludwig Scale measures the severity.

This form of hair loss is progressive but manageable with early treatment. Medications like minoxidil and finasteride are commonly used, with newer options like PRP therapy and low-level laser therapy also gaining popularity.

Medical & Autoimmune Causes

Alopecia Areata: The Body vs. Itself

Alopecia areata is an autoimmune condition where the immune system mistakenly attacks hair follicles, leading to patchy hair loss on the scalp or other parts of the body. It’s unpredictable and can range from small bald spots to complete hair loss (alopecia totalis). This form of hair loss is not contagious and often begins suddenly. Stress, viral infections, or genetics may act as triggers.

Treatment often includes topical or injectable corticosteroids, immunotherapy, or newer JAK inhibitor medications. While full regrowth is possible, recurrence is common.

Telogen Effluvium: Shock-Related Shedding

Another common yet temporary condition is telogen effluvium, typically triggered by:

• High fever or illness (e.g., COVID-19 recovery)
• Major surgery or childbirth
• Crash diets or sudden weight loss
• Emotional stress or trauma

Hair enters the resting (telogen) phase prematurely, resulting in increased shedding 2–3 months after the event. Recovery usually begins within 6 months without treatment, although nutritional support or stress management may help speed up regrowth.

Hormonal & Deficiency-Related Conditions

• Thyroid imbalances (both hyper- and hypothyroidism) can cause hair thinning.
• PCOS (Polycystic Ovary Syndrome) in women leads to excess androgens, promoting male-pattern hair loss.
• Iron-deficiency anemia, vitamin D deficiency, and low B12 are frequent nutritional hair loss causes, especially in women.

If you’re experiencing sudden hair loss, it’s important to get blood tests to rule out these underlying conditions.

Medication & Treatment-Related Hair Loss

Chemotherapy-Induced Alopecia

One of the most widely known medical causes of hair loss is chemotherapy. These medications target rapidly dividing cells—not only cancer cells but also hair follicles. As a result, sudden hair loss can begin within a few weeks of treatment. Hair typically regrows after therapy ends, although texture and color may change.

Preventive methods like scalp cooling caps can help reduce blood flow to hair follicles during chemotherapy, potentially minimizing the extent of loss.

Other Medications That Cause Hair Loss

Beyond cancer treatment, many medications can interfere with the normal hair cycle and lead to shedding:

• Beta-blockers (used for high blood pressure)
• Retinoids (Vitamin A derivatives used in dermatology)
• Anticoagulants (like warfarin or heparin)
• Antidepressants and mood stabilizers
• Anticonvulsants
• Hormone therapies (including birth control pills or testosterone treatments)

These medications may cause telogen effluvium, where hair prematurely shifts into the shedding phase.

What You Can Do

If you suspect a medication is causing thinning or patchy hair loss:

• Don’t stop any prescription without consulting your doctor.
• Ask if there are alternatives with less hair-related side effects.
• Nutritional support and topical therapies like minoxidil may help improve density while continuing necessary medications.

Nutritional Deficiencies & Lifestyle Triggers

Nutritional Hair Loss Causes

Your hair is one of the first places your body reflects a nutritional imbalance. Certain deficiencies can interrupt the natural growth cycle and trigger hair loss reasons like increased shedding or slower regrowth.

Key nutrients linked to hair health include:

• Iron – especially important for women; low levels are linked to diffuse hair thinning
• Vitamin D – deficiencies are associated with alopecia areata and poor follicle health
• Biotin (B7) – though true deficiencies are rare, it plays a role in keratin production
• Zinc – supports cell repair and hair tissue growth
• Protein – inadequate intake affects the structural integrity of hair shafts
• Omega-3 fatty acids – support healthy scalp and reduce inflammation

These are especially relevant when evaluating hair loss causes in women, who are more prone to iron and vitamin-related deficiencies due to menstruation, pregnancy, or restrictive dieting.

Lifestyle Factors That Worsen Hair Loss

Some daily habits and choices may unknowingly put stress on your follicles:

• Tight hairstyles (buns, braids, ponytails) may cause traction alopecia
• Overuse of heat tools and chemical treatments damages the hair shaft
• Crash diets or eating disorders reduce vital nutrient intake
• Smoking impairs circulation, affecting follicle oxygenation
• Poor sleep and chronic fatigue are linked to higher cortisol levels and shedding

How to Address It

• Include protein-rich meals, leafy greens, eggs, and fatty fish in your diet
• Consider lab testing for nutritional hair loss causes, especially if experiencing sudden hair loss
• Use gentle hair care practices and reduce physical stress to the scalp

Identifying these underlying nutritional or lifestyle triggers helps treat not only the symptoms but the actual root causes.

Scalp Infections & Dermatologic Conditions

Fungal Infections and Hair Loss

Scalp infections—especially fungal types—are among the lesser-known but impactful causes of patchy hair loss. One of the most common culprits is tinea capitis, a ringworm infection of the scalp. It usually leads to scaly, inflamed patches with broken hairs and is more common in children but can affect adults too.

Early diagnosis and antifungal treatment are essential. Without prompt care, it may lead to scarring and permanent hair loss in severe cases.

Seborrheic Dermatitis & Folliculitis

Other skin-related conditions that can interfere with hair health:

• Seborrheic dermatitis: Characterized by dandruff, redness, and itchiness. Inflammation can weaken follicles over time and trigger shedding.
• Folliculitis: Inflammation or infection of hair follicles. Bacterial or fungal in nature, it can cause tenderness and pustules that disrupt the hair growth cycle.
• Psoriasis: Although primarily a skin condition, scalp psoriasis can lead to temporary hair thinning due to the buildup of plaques and scratching.

These conditions might not directly destroy the follicles but contribute to stress hair loss through chronic inflammation and irritation.

When to Seek Help

• If you notice redness, scaling, itching, or pus-filled bumps on your scalp
• If hair loss appears in patches or areas with visible inflammation
• If over-the-counter anti-dandruff or medicated shampoos don’t improve symptoms

Dermatologists may recommend antifungal creams, oral medications, or prescription shampoos depending on the diagnosis. Managing scalp health is essential for maintaining healthy hair and preventing avoidable loss linked to infections.

Other Triggers: Age, Stress, Postpartum

Age-Related Hair Thinning

One of the most common hair loss reasons is simply getting older. As people age, hair follicles shrink, the growth phase shortens, and new hairs grow thinner. This affects both men and women, although patterns differ. In men, FUE hair transplant becomes more common as a corrective option for male pattern baldness, while in women, diffuse thinning is more frequent due to hormonal shifts after menopause.

Unlike some other causes, age-related hair loss tends to be gradual and permanent. However, treatments like minoxidil, PRP therapy, and lifestyle adjustments may slow the process.

Stress-Induced Hair Loss (Telogen Effluvium)

Stress doesn’t just impact your mind; it shifts your hair into the resting phase. This results in a type of shedding called telogen effluvium, where more follicles than usual stop producing hair for a period of time.

Common triggers include:

• Emotional stress (grief, anxiety, trauma)
• Physical stress (illness, surgery, weight loss)
• Major life changes (job loss, divorce, burnout)

Shedding typically begins 2–3 months after the stressor and may last several months. Unlike scarring alopecias, follicles are not permanently damaged—recovery is possible with time, reduced stress, and healthy nutrition.

Pregnancy Hair Loss Causes & Postpartum Shedding

Many women enjoy thicker hair during pregnancy due to elevated estrogen, but this often reverses after childbirth. As hormone levels drop, a sharp increase in shedding—postpartum telogen effluvium—can occur.

This usually begins around 2–4 months after delivery and resolves within 6–12 months. Still, it can be alarming if unexpected. Supportive care includes:

• A nutrient-dense diet (especially iron, zinc, biotin)
• Stress management and adequate sleep
• Gentle styling and scalp massage to stimulate circulation

Step-by-Step Self-Check Guide for Hair Loss

Why Self-Assessment Matters

Recognizing early signs of shedding and identifying potential causes of hair loss can improve treatment outcomes. A structured self-check helps determine if the problem is minor or needs professional attention. Below is a practical method anyone can use at home to assess their condition before visiting a dermatologist.

The Zone Hair Pull Test (Simple Home Method)

This quick test checks if you’re shedding more than usual:

Don’t wash your hair for 48 hours.

Grasp around 40–60 hairs between your thumb and fingers.

Gently tug from the root, covering these zones:

• Front hairline
• Crown (top of scalp)
• Back of the scalp
• Sides (temples and above ears)

If more than 6 hairs come out from one zone, and this repeats across multiple areas, it could point to diffuse shedding like telogen effluvium or nutritional hair loss causes.

What to Observe

• Is shedding even across the scalp? (points to stress, deficiency)
• Is it patchy? (could be alopecia areata or infection)
• Is the scalp itchy, flaky, or red? (possible scalp infections or dermatitis)

When to See a Doctor

Self-checks offer clues, but seeing a specialist is vital when:

• Hair loss continues for more than 3 months
• You notice bald patches or clear scalp visibility
• There’s pain, burning, or inflammation on the scalp
• You have a family history of genetic hair loss

Early professional evaluation often includes:

• Blood tests (iron, thyroid, hormones)
• Scalp biopsy (for autoimmune causes)
• Trichoscopy (microscopic scalp imaging)

Combining these tests with your self-observations allows for a precise diagnosis and tailored treatment plan.

Treatment Ties to Cause: What Works for Each Type of Hair Loss

Why Identifying the Cause Matters for Treatment

Not every hair loss treatment fits all situations. What works for genetic hair loss may be useless for nutritional deficiency or stress-induced shedding. Once the underlying trigger is identified—whether it’s hormonal, medical, or lifestyle-related—treatment can be personalized for lasting results.

Match Causes to the Right Treatments

Below is a breakdown of effective treatments based on key hair loss causes:

Genetic & Hormonal (Androgenetic Alopecia)

• Minoxidil (topical): Encourages growth and prolongs the anagen phase
• Finasteride (oral): Blocks DHT (only for men)
• Hair Transplant (FUE or DHI): For advanced loss with permanent balding
• PRP (Platelet-Rich Plasma): Stimulates dormant follicles

Ideal for: FUE hair transplant Turkey or FUE hair transplant UK seekers with clear balding patterns.

Medical & Autoimmune (Alopecia Areata, Thyroid, PCOS)

• Corticosteroid injections or creams: Reduce immune attack on follicles
• Treating underlying disease: Thyroid medication, PCOS regulation
• Immunotherapy (topical or oral): Used in moderate-severe cases

Ideal for: People with medical causes of hair loss or patchy shedding.

Stress or Telogen Effluvium

• No drugs needed in most cases

Focus on:

• Reducing stress
• Balanced sleep and rest
• Time (3–6 months recovery expected)

Supportive: Iron, zinc, B vitamins if low. Important for stress hair loss and pregnancy hair loss causes.

Nutritional Deficiency

• Correct the lacking nutrient (e.g., iron, vitamin D, biotin, protein)
• Dietitian support for long-term balance
• Multivitamins help only when targeted

Watch for: nutritional hair loss causes and slow but full regrowth with correction.

General Scalp & Hair Health Boosters

• Gentle shampoos: Free of sulfates and parabens
• Medicated shampoos: For dandruff, dermatitis
• Laser therapy (LLLT): Supports blood flow to the scalp
• Scalp massage + dermarolling: Enhances circulation

By matching treatment to the root cause, patients avoid wasting time and money on ineffective methods.

Prevention & Maintenance Tips for Long-Term Hair Health

Why Prevention is Easier Than Cure

Once hair loss begins, reversing it takes time and consistency. But smart daily habits and scalp care can slow or even stop future thinning. These prevention tips apply to both men and women—especially those with genetic risk or post-treatment recovery needs.

Daily Habits That Support Hair Strength

Here’s what you can do consistently to protect your hair from common hair loss causes:

• Follow a balanced diet: Include iron, vitamin D, B12, zinc, protein, and omega-3s. Deficiencies often trigger nutritional hair loss causes.
• Limit heat styling: Straighteners and curling tools damage the hair shaft.
• Avoid tight hairstyles: Prevents traction alopecia, especially with braids, buns, and ponytails.
• Wash with care: Use gentle, pH-balanced shampoos. Avoid daily washing unless necessary.
• Massage your scalp: Stimulates circulation, encourages follicle activity.

Supplements That Might Help

Targeted supplements work when you have known deficiencies:

• Biotin: Often used for hair and nails, but only effective if you’re low
• Iron & B12: Essential for women, vegetarians, or those with anemia
• Vitamin D: Linked with various hair loss reasons, especially autoimmune cases

Stress & Hormonal Balance

• Manage stress levels: Practice mindfulness, breathing exercises, or physical activity
• Regular check-ups: Especially for thyroid, PCOS, and other medical causes of hair loss
• Postpartum care: Be patient—pregnancy hair loss causes are often temporary

Long-Term Maintenance for Treated Hair

If you’ve already had a transplant or are using medications:

• Stick with minoxidil or finasteride as directed
• Follow transplant aftercare instructions to reduce shedding and boost growth
• Use scalp-friendly serums and DHT-blocking shampoos if advised by a doctor

Conclusion & Next Steps

Understanding the causes of hair loss is the first step toward finding the right solution. Whether it’s genetics, hormonal imbalance, autoimmune disease, or lifestyle factors, identifying the root trigger makes treatment more effective and targeted.

Hair loss doesn’t have a one-size-fits-all solution. Some cases may improve with minor dietary adjustments or stress management, while others require medical intervention like minoxidil, finasteride, or even surgical procedures like hair transplantation.

If you’re unsure whether your shedding is temporary or chronic, start with the self-check methods outlined above and track changes for a few weeks. However, if hair thinning worsens or you’re experiencing patchy bald spots, it’s time to consult a dermatologist. They can run the necessary tests—such as bloodwork for nutritional deficiencies or hormone panels—to pinpoint the exact cause.

Final Tips Before You Act

• Be consistent. Treatments take time—results aren’t immediate.
• Avoid miracle cures online. Trust evidence-based treatments.
• Early action is key. The sooner you address the cause, the more hair you can potentially save.

Whether you’re experiencing stress hair loss, alopecia areata, or a medical cause of hair loss, your recovery starts with the right diagnosis and a personalized plan.

Take the first step today by booking a consultation with Hermest Hair Clinic.

FAQs

What causes sudden hair loss?

Sudden hair loss is often triggered by stress, illness, hormonal shifts, or medication side effects. Telogen effluvium is the most common condition linked to rapid shedding, where hair prematurely enters the resting phase. Identifying the root trigger early helps improve recovery.

How does stress cause hair loss?

Stress disrupts the hair growth cycle by pushing follicles into a resting phase (telogen). This leads to shedding a few months later. High cortisol levels and emotional trauma are key factors. Reducing stress through lifestyle changes can help normalize hair regrowth.

Who is most at risk of hair loss?

Men are more likely to experience genetic hair loss (androgenetic alopecia), especially with a family history. Women may also be affected, particularly after childbirth or during menopause. People with autoimmune diseases or poor nutrition are also at increased risk.

Why do women lose hair after pregnancy?

Hormonal shifts after delivery often lead to a condition called postpartum telogen effluvium. During pregnancy, high estrogen levels keep hair in the growth phase. After birth, hormone levels drop, triggering temporary hair shedding. It usually resolves within 6 to 12 months.

Where does hair loss usually start in men and women?

In men, hair loss often begins at the temples or crown (Norwood scale). In women, it tends to present as diffuse thinning along the top of the scalp (Ludwig scale), rarely leading to complete baldness. Understanding these patterns helps in diagnosis.

What are the medical causes of hair loss?

Hair loss can result from thyroid disease, PCOS, anemia, or autoimmune conditions like alopecia areata. These disrupt hair follicle function or blood flow to the scalp. Blood tests are usually needed to confirm medical causes and guide treatment.

Will hair grow back after chemotherapy?

Yes, hair often regrows after chemotherapy, but the texture or color may change. Regrowth usually starts 2–3 months post-treatment. Cooling caps can sometimes reduce the severity of chemo-induced hair loss. Results vary depending on the type of drugs used.

How does diet affect hair loss?

Nutritional deficiencies, especially in iron, vitamin D, protein, and biotin, can weaken hair and trigger shedding. A poor diet deprives follicles of key nutrients. Correcting deficiencies through food or supplements can significantly improve hair density and strength.

What is the difference between genetic and environmental hair loss?

Genetic hair loss is hereditary and progressive, often linked to sensitivity to DHT. Environmental factors like stress, diet, and pollution cause non-genetic hair loss, which is often reversible. Understanding the distinction helps target effective treatment options.

Will changing hairstyles prevent hair thinning?

Yes, avoiding tight hairstyles such as ponytails, braids, or extensions can reduce traction alopecia. Constant tension on hair roots leads to gradual thinning and possible permanent damage. Loose styles and protective routines help maintain scalp health.