Hair thinning in women is common and often multifactorial. Understanding the underlying cause is essential, as treatment depends on an accurate diagnosis.

Common Causes of Hair Thinning in Women

1. Female Pattern Hair Loss (Androgenetic Alopecia)

This is the most common cause of progressive hair thinning in women. It typically presents as diffuse thinning over the crown and mid-scalp while preserving the frontal hairline. Genetics and sensitivity of hair follicles to androgens play a key role.

2. Hormonal Changes

Hormonal fluctuations can significantly affect the hair growth cycle, including:

• Pregnancy and postpartum changes
• Menopause
• Polycystic ovary syndrome (PCOS)
• Thyroid disorders (hypothyroidism or hyperthyroidism)

These conditions can shorten the growth phase of hair, leading to increased shedding and thinning.

3. Telogen Effluvium

Telogen effluvium is a temporary but noticeable form of hair thinning caused by a disruption in the hair cycle. Common triggers include:

• Physical or emotional stress
• Major illness or surgery
• Rapid weight loss
• High fever or infections

Hair shedding usually occurs 2–3 months after the triggering event.

4. Nutritional Deficiencies

Insufficient intake or absorption of key nutrients can weaken hair follicles. Common deficiencies include:

• Iron (especially in menstruating women)
• Vitamin D
• Vitamin B12
• Protein

Correcting the deficiency often improves hair density over time.

5. Aging

As women age, hair growth slows, and individual strands become finer. This natural process can result in gradual thinning, particularly after menopause.

6. Autoimmune Conditions

Conditions such as alopecia areata cause patchy hair loss due to immune-mediated follicle attack. Other autoimmune disorders may also contribute indirectly.

7. Scalp Conditions

Chronic scalp inflammation can impair healthy hair growth. Examples include:

• Seborrheic dermatitis
• Psoriasis
• Chronic fungal or bacterial infections

An unhealthy scalp environment can weaken follicles and increase shedding.

8. Excessive Hair Styling or Traction

Repeated tension from tight hairstyles (ponytails, braids), chemical treatments, or heat styling can cause traction alopecia, leading to thinning along the hairline or temples.

9. Medications

Certain medications may contribute to hair thinning, including:

• Hormonal contraceptives
• Antidepressants
• Blood pressure medications
• Chemotherapy and other systemic treatments

Medication-related hair loss is often reversible once the drug is discontinued or adjusted.

When to See a Specialist

If hair thinning is progressive, sudden, or accompanied by other symptoms such as fatigue, menstrual changes, or scalp irritation, evaluation by a dermatologist or hair restoration specialist is recommended. Early diagnosis improves treatment outcomes.