Hair Loss Causes: Complete Guide

Overview: Why Does Hair Fall Out?

Hair loss can result from numerous factors, ranging from genetics to lifestyle choices. Understanding the root cause of your hair loss is crucial for selecting effective treatments. Below we cover all major categories of hair loss causes.

1. Genetic Factors (Androgenetic Alopecia)

Genetic hair loss, also known as androgenetic alopecia, is the most common cause of hair loss, affecting over 80 million Americans. It can be inherited from either parent and manifests differently in men and women.

Male Pattern Baldness

Male pattern baldness typically follows a predictable pattern starting with a receding hairline and thinning at the crown. The Norwood Scale is used to classify the stages of male hair loss.

• Prevalence: 50% of men by age 50, 85% by age 70
• Pattern: Receding hairline, crown thinning, eventual baldness
• Cause: Sensitivity to DHT (dihydrotestosterone)
• Treatment: Finasteride, minoxidil, hair transplant

Female Pattern Hair Loss

Female pattern hair loss differs from male pattern baldness, typically causing diffuse thinning across the crown while preserving the frontal hairline. The Ludwig Scale classifies female hair loss stages.

• Prevalence: 40% of women by age 50
• Pattern: Diffuse thinning on top, widening part
• Cause: Complex hormonal and genetic factors
• Treatment: Minoxidil, spironolactone, PRP therapy

2. Hormonal Factors

Hormones play a crucial role in hair growth and loss. Both hormone excesses and deficiencies can trigger hair loss.

DHT (Dihydrotestosterone)

• Primary hormone responsible for genetic hair loss
• Converted from testosterone by 5-alpha-reductase enzyme
• Causes follicle miniaturization in genetically sensitive areas
• Blocked by medications like finasteride and dutasteride

Thyroid Disorders

• Hypothyroidism: Causes diffuse hair thinning and dry, brittle hair
• Hyperthyroidism: Can cause fine, thin hair and increased shedding
• Treatment: Thyroid hormone optimization often reverses hair loss

Female Hormonal Changes

• Pregnancy: Hair often thickens during pregnancy due to high estrogen
• Postpartum: Hair loss 2-6 months after delivery is common
• Menopause: Declining estrogen unmasks genetic hair loss
• PCOS: Elevated androgens can cause early-onset female pattern hair loss

3. Autoimmune Conditions

Several autoimmune conditions can attack hair follicles, causing various patterns of hair loss.

Alopecia Areata

Alopecia areata is an autoimmune condition where the immune system attacks hair follicles, causing circular patches of hair loss.

• Prevalence: Affects approximately 2% of the population
• Subtypes: Patchy (localized), totalis (complete scalp), universalis (entire body)
• Recovery: Many experience spontaneous regrowth; treatments available

Other Autoimmune Conditions

• Lupus: Can cause scarring hair loss
• Hashimoto's thyroiditis: Autoimmune thyroid disease causing hair thinning
• Psoriasis: Can affect the scalp and cause temporary hair loss

4. Stress-Related Hair Loss

Both physical and emotional stress can trigger significant hair loss, typically manifesting as telogen effluvium.

Physical Stressors

• Major surgery or illness
• High fever (including COVID-19)
• Severe weight loss or crash dieting
• Childbirth
• Chronic illness

Emotional Stressors

• Death of a loved one
• Divorce or relationship issues
• Job loss or financial stress
• Chronic anxiety or depression

Learn more about stress-related hair loss recovery timeline and what to expect during the healing process.

5. Nutritional Deficiencies

Hair follicles require adequate nutrition to function properly. Several deficiencies can lead to hair loss:

• Iron: Most common nutritional cause; especially in women
• Protein: Hair is made of keratin, a protein
• Vitamin D: Low levels linked to hair loss
• B vitamins: Especially biotin (B7) and B12
• Zinc: Essential for hair tissue growth
• Omega-3 fatty acids: Support scalp health

Discover how to stop hair loss naturally through proper nutrition and supplementation.

6. Medications That Cause Hair Loss

Many medications can cause hair loss as a side effect. This is usually reversible once the medication is stopped.

• Chemotherapy: Most causes dramatic but temporary hair loss
• Blood thinners: Heparin, warfarin
• Antidepressants: Some SSRIs and lithium
• Blood pressure medications: Beta-blockers, ACE inhibitors
• Retinoids: High-dose vitamin A
• Immunosuppressants: Methotrexate and others
• Hormonal medications: Some birth control pills, hormone therapy

7. Physical Damage to Hair

External factors can damage hair follicles and cause hair loss:

Traction Alopecia

• Caused by tight hairstyles (ponytails, braids, cornrows)
• Can become permanent if continued long-term
• Prevention: Loose hairstyles, avoiding tension on hairline

Heat and Chemical Damage

• Excessive heat styling weakens hair shaft
• Chemical relaxers and perms can damage follicles
• Over-bleaching causes breakage (not true hair loss)

How to Identify Your Hair Loss Cause

Determining the cause of your hair loss typically involves:

1. Pattern analysis: Where and how is hair thinning?
2. Timeline: When did it start? Sudden or gradual?
3. Medical history: Recent illness, medications, stress?
4. Family history: Do parents or siblings have hair loss?
5. Blood tests: Check thyroid, iron, hormones, vitamins
6. Scalp examination: Look for signs of infection or inflammation

Conclusion

Hair loss can result from many different causes, often with multiple factors contributing simultaneously. Understanding the underlying cause is essential for selecting the most effective treatment approach.

Whether your hair loss is genetic, hormonal, stress-related, or due to medical conditions, there are treatment options available. The key is accurate diagnosis and early intervention for the best possible outcomes.

If you're experiencing hair loss, learn about whether hair loss can be reversed and explore our comprehensive treatment guide for all available options.