What Is the Cause of Hair Loss?

HEREDITY

Both men and women tend to lose hair thickness and amount with age. This type of baldness is usually not due to disease, but rather aging, genetics, and hormonal changes — especially testosterone. Pattern baldness, which is inherited, affects more men than women. Male pattern baldness can begin after puberty, and around 80% of men show signs by age 70.

PHYSICAL OR EMOTIONAL STRESS

Stress can cause **telogen effluvium**, where 50–75% of scalp hair may shed suddenly. Hair may fall out in handfuls when brushing or washing. This type of hair loss can occur weeks to months after the stress and typically reverses in 6 to 8 months.

Common causes include:

• High fever or severe infection
• Childbirth
• Major surgery, illness, or sudden blood loss
• Severe emotional stress
• Crash diets, especially low in protein
• Medications like retinoids, birth control pills, beta-blockers, calcium channel blockers, antidepressants, and NSAIDs

Some women (ages 30 to 60) may experience gradual thinning over the scalp without a known cause. This usually slows or stops over time.

OTHER CAUSES

Unusual patterns or sudden hair loss may be caused by:

• Alopecia areata (patchy bald spots)
• Anemia
• Autoimmune diseases like lupus
• Burns
• Infections like syphilis
• Excessive shampooing or heat styling
• Hormonal changes
• Thyroid disorders
• Trichotillomania (hair pulling)
• Radiation therapy
• Ringworm of the scalp (tinea capitis)
• Ovarian or adrenal tumors
• Hair styles that pull tightly on the scalp
• Bacterial scalp infections

If hair loss is sudden, severe, or in an unusual pattern, it's important to seek medical evaluation to rule out underlying conditions.