What causes hair to stop growing without falling out?

Causes of Hair That Stops Growing Without Falling Out

When hair stops growing but remains attached to the scalp, this is most likely due to an arrest in the normal hair growth cycle, particularly conditions affecting the anagen (growth) phase of hair follicles. 1

Common Causes

1. Alopecia Areata

Alopecia areata is an autoimmune condition that can cause hair to stop growing without immediate shedding. The immune system attacks hair follicles, causing them to enter a dormant state.

• Key features:
  • T-lymphocyte mediated attack on hair follicles 1
  • Often presents as patches of hair that appear "frozen" in time
  • Exclamation mark hairs (short broken hairs) may be visible at the margins 1
  • Dermoscopy shows yellow dots and dystrophic hairs 1

2. Anagen Effluvium

This condition directly affects actively growing hair follicles, causing them to stop growing without immediate shedding.

• Common triggers:
  • Chemotherapy drugs 2
  • Radiation therapy
  • Toxic exposures that impair the mitotic activity of hair follicles 2
  • The hair stops growing but may remain attached temporarily

3. Trichotillomania

This impulse-control disorder can present as areas where hair appears to have stopped growing.

• Distinguishing features:
  • Broken hairs remain firmly anchored in the scalp 1
  • Incomplete nature of hair loss 1
  • Hairs remain in anagen (growing) phase despite appearing stunted 1
  • May coexist with alopecia areata, causing diagnostic confusion 1

4. Early Scarring Alopecia

In early stages, scarring alopecia may present as hair that stops growing before visible scarring occurs.

• Warning signs:
  • Subtle inflammation
  • Mild erythema
  • Hair appears to be "frozen" in place before falling out
  • Eventually leads to permanent hair loss if untreated 1

5. Endocrine Disorders

Hormonal imbalances can affect the hair growth cycle without causing immediate shedding.

• Common conditions:
  • Hypothyroidism
  • Hyperthyroidism
  • Androgen excess disorders
  • Polycystic ovary syndrome (particularly in women) 3

Diagnostic Approach

When evaluating hair that has stopped growing:

1. Visual examination:

   • Look for exclamation mark hairs (alopecia areata) 1
   • Check for broken hairs firmly anchored in scalp (trichotillomania) 1
   • Assess for subtle inflammation (early scarring alopecia)
   • Examine hair shaft for structural abnormalities

2. Dermoscopy can provide valuable diagnostic clues:

   • Yellow dots in alopecia areata 1
   • Dystrophic hairs with fractured tips in alopecia areata 1
   • Cadaverized hairs (fractured before emergence) 1

3. Investigations when diagnosis is uncertain:

   • Skin biopsy (especially for suspected scarring alopecia) 1
   • Fungal culture (to rule out tinea capitis) 1
   • Serology for lupus erythematosus or syphilis if clinically indicated 1
   • Thyroid function tests

Management Considerations

Management should be directed at the underlying cause:

• Alopecia areata: Treatment options include intralesional corticosteroids for limited patches 1
• Anagen effluvium: Supportive care and removal of triggering agent 2
• Trichotillomania: Treatment of underlying psychiatric condition 2
• Early scarring alopecia: Prompt dermatology referral for early intervention
• Endocrine disorders: Treatment of underlying hormonal imbalance

Important Caveats

• Hair growth arrest without shedding is often temporary in non-scarring conditions but may be permanent in scarring alopecias
• Psychological impact can be significant and should not be underestimated 1, 3
• Some patients may benefit from psychological support, especially when the condition is chronic or extensive 1
• Spontaneous regrowth is common in conditions like alopecia areata but may take months 1
• Avoid potentially hazardous treatments with unproven efficacy, especially since many conditions may resolve spontaneously 1

Remember that accurate diagnosis is crucial for appropriate management, and dermatology referral should be considered for cases that are difficult to diagnose or manage.