1. Genetic (Hereditary) Hair Loss

Condition: Male pattern baldness (androgenetic alopecia)
Description: Gradual thinning starting at the temples or crown, sometimes progressing to complete baldness on top.
Cause: Genetic sensitivity of hair follicles to dihydrotestosterone (DHT), a byproduct of testosterone.
Timing: Can begin as early as the late teens or early 20s.

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2. Hormonal Changes

• Elevated DHT levels can shorten the growth phase of hair and cause follicles to shrink.
• Hormonal imbalances from conditions like thyroid disorders or anabolic steroid use can also contribute.

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3. Medical Conditions

Possible causes include:

• Thyroid disease (hypothyroidism or hyperthyroidism)
• Autoimmune disorders (e.g., alopecia areata, where the immune system attacks hair follicles)
• Scalp infections such as ringworm
• Chronic illnesses or high fevers

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4. Nutritional Deficiencies

Healthy hair growth requires adequate nutrition. Hair loss can be linked to:

• Low iron or zinc levels
• Vitamin D deficiency
• Insufficient protein intake
• Deficiencies in B vitamins (especially biotin and B12)
• Rapid weight loss or restrictive diets

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5. Stress and Psychological Factors

Condition: Telogen effluvium
Cause: Physical or emotional stress (such as surgery, illness, or trauma) can push hair follicles into the resting phase, leading to temporary shedding.
Timing: Typically occurs 2–3 months after the stressful event.

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6. Medications and Medical Treatments

Some medications can cause temporary or permanent hair loss, including:

• Chemotherapy or radiation therapy
• Antidepressants
• Beta-blockers
• Blood thinners
• Retinoids (vitamin A derivatives)
• Steroids and anabolic hormones

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7. Hair Care and Styling Practices

• Tight hairstyles (man buns, braids) can cause traction alopecia.
• Frequent use of harsh chemicals, heat, or dyes can damage hair shafts.

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8. Aging

As men age, hair follicles shrink and produce thinner, shorter hairs. The growth rate also slows, leading to gradual thinning even without a clear genetic cause.

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8. Other Contributing Factors

• Smoking, which restricts blood flow to the scalp
• Excessive alcohol consumption
• Chronic inflammation or poor scalp health