Telogen Effluvium: Understanding Temporary Hair Shedding

What is Telogen Effluvium?

Telogen effluvium is a prevalent form of temporary hair loss characterized by excessive shedding of hair. It occurs when a larger-than-normal percentage of hair follicles prematurely shift from the anagen (growth) phase into the telogen (resting) phase. Normally, about 10-15% of hairs are in the telogen phase at any given time, where they remain for approximately three months before shedding. In telogen effluvium, this percentage can increase significantly, leading to noticeable hair loss, often several months after a triggering event.

Unlike androgenetic alopecia, which typically involves miniaturization of hair follicles and a progressive reduction in hair shaft diameter, telogen effluvium primarily affects the hair cycle itself, causing a sudden and diffuse thinning across the scalp rather than localized baldness. The hair follicles themselves usually remain healthy and capable of re-entering the anagen phase, making the condition largely reversible.

The Hair Growth Cycle

To understand telogen effluvium, it's essential to grasp the basics of the hair growth cycle:

• Anagen (Growth Phase): This is the active growth phase, lasting between 2-7 years, where hair cells rapidly divide, and the hair shaft grows. Approximately 85-90% of hairs are in this phase.
• Catagen (Transition Phase): A short transitional phase lasting about 2-3 weeks, during which hair growth stops, and the follicle shrinks.
• Telogen (Resting Phase): This phase lasts around 3 months. The hair remains in the follicle but is inactive. At the end of this phase, the hair sheds.
• Exogen (Shedding Phase): While often considered part of telogen, some refer to exogen as the specific process of hair shedding from the follicle as new hair begins to grow.

In telogen effluvium, various stressors disrupt this natural cycle, prompting a synchronous and early entry of a large number of anagen hairs into the telogen phase. This leads to widespread shedding approximately 2-4 months after the initial trigger.

Common Triggers of Telogen Effluvium

Telogen effluvium is typically provoked by a significant physical or psychological stressor that systemically affects the body. Identifying the trigger is crucial for managing the condition. Common causes include:

• Physiological Stress:
  • Major Surgery: The body