What causes hair to stop growing?

Causes of Hair Growth Cessation

Hair growth can stop due to various conditions, with autoimmune-mediated alopecia areata being the most common non-scarring cause that can progress to complete hair loss in severe cases. 1

Primary Causes of Hair Growth Cessation

1. Autoimmune Conditions

• Alopecia Areata: A T-lymphocyte mediated autoimmune condition affecting the hair follicle
  • Presents as patches of hair loss on the scalp or any hair-bearing skin
  • Can progress to total scalp hair loss (alopecia totalis) or complete body hair loss (alopecia universalis) in 14-25% of cases 1
  • Genetic predisposition exists with 20% having a family history 1
  • Associated with other autoimmune diseases

2. Nutritional Factors

• Nutritional Deficiencies: Various micronutrient deficiencies can disrupt the normal hair cycle 2, 3
  • Iron deficiency (though routine testing not recommended without other symptoms) 1
  • Vitamin deficiencies (A, B, C, D, E) 3
  • Mineral deficiencies (zinc, selenium) 3

3. Physical/Mechanical Factors

• Trichotillomania: Compulsive hair pulling that can be confused with alopecia areata 1
• Traction Alopecia: From tight hairstyles or excessive pulling

4. Inflammatory/Infectious Conditions

• Tinea Capitis: Fungal infection of the scalp 1
• Scarring Alopecia: Various inflammatory conditions leading to permanent hair loss 1
• Systemic Lupus Erythematosus: Can cause hair loss 1
• Secondary Syphilis: Can present with patchy hair loss 1

5. Hormonal/Metabolic Factors

• Endocrine Imbalances: Thyroid disorders, hormonal changes 4
• Telogen Effluvium: Stress-induced shedding causing diffuse hair loss 1, 4

6. Drug-Induced Hair Loss

• Anagen Effluvium: Chemotherapy or radiation therapy 1, 4
• Medication Side Effects: Various drugs can cause hair loss 4

Diagnostic Approach

Key Clinical Features

• Pattern of hair loss (patchy, diffuse, or complete)
• Presence of "exclamation mark hairs" (characteristic of alopecia areata) 1
• Scalp appearance (normal in alopecia areata, inflamed in tinea capitis) 1
• Dermoscopic findings:
  • Yellow dots, dystrophic hairs with fractured tips in alopecia areata 1
  • Firmly anchored broken hairs in trichotillomania 1

Investigations (when diagnosis is uncertain)

• Fungal culture (for suspected tinea capitis) 1
• Skin biopsy (for uncertain diagnosis or suspected scarring alopecia) 1
• Serology for lupus erythematosus or syphilis when clinically indicated 1

Prognosis and Natural History

The prognosis varies significantly depending on the cause:

• Alopecia Areata:
  • Spontaneous remission within 1 year occurs in 34-50% of cases seen in specialty clinics 1
  • Up to 80% of patients with limited patchy hair loss may experience spontaneous remission 1
  • Poor prognosis factors include:
    • Childhood onset
    • Extensive hair loss at presentation (>50% scalp involvement)
    • Long-standing disease
    • Ophiasis pattern (hair loss at scalp margins) 1

Management Considerations

Treatment depends on identifying the underlying cause:

• Alopecia Areata: No treatment has been shown to alter the disease course, though various treatments can induce hair growth 1
• Nutritional Deficiencies: Correction of specific deficiencies may help restore hair growth 2, 3
• Oxidative Stress: Antioxidant nutrients may help counter oxidative stress, a major mediator of hair loss 5

Important Caveats

• Hair follicles are preserved in alopecia areata, maintaining potential for recovery even in longstanding disease 1
• Many cases of limited alopecia areata resolve spontaneously, making "no treatment" a legitimate option 1
• Hazardous treatments should be avoided given that hair loss conditions generally don't impact overall health 1
• Psychological impact of hair loss can be significant and should be addressed 1

Understanding the specific cause of hair growth cessation is essential for appropriate management and setting realistic expectations regarding potential for regrowth.