Pubic hair is terminal hair, which is thicker and darker than the fine vellus hair covering the rest of the body. The apparent ease of shedding is due to the body’s programmed hair growth cycle. This normal turnover is rooted in the unique, shorter duration of the growth phase compared to scalp hair.
Understanding the Hair Growth Cycle
All hair on the human body follows a regulated, cyclical process of growth, transition, and rest. This cycle is divided into three phases that govern the life span of a single hair strand.
The Anagen phase is the period of active growth where cells in the hair root divide rapidly to form the hair shaft. Hair remains firmly anchored in the follicle throughout this time.
The Catagen phase is a short transitional period lasting two to three weeks. During this time, hair growth stops, the follicle shrinks, and the hair detaches from its blood supply.
The final stage is the Telogen phase, a resting period that typically lasts two to four months, where the hair remains dormant. Shedding occurs at the end of this phase, often called the Exogen phase, when the old hair is released to make way for a new Anagen hair.
Losing a certain number of hairs daily is part of the natural hair cycle resetting itself. This mechanism ensures the body maintains a constant supply of hair without all strands shedding simultaneously.
Distinct Characteristics of Pubic Hair
The reason pubic hair sheds more easily than scalp hair is the dramatically different duration of the Anagen phase. Scalp hair’s Anagen phase lasts two to seven years, allowing it to grow long. In contrast, the Anagen phase for pubic hair is significantly shorter, typically lasting only a few months.
This short growth period dictates the maximum length pubic hair can achieve before it is programmed to shed. A shorter active growth phase means the hair follicle reaches the Telogen phase much faster and more frequently, creating a regular shedding pattern.
The development of this robust terminal hair is triggered by rising levels of androgens, such as testosterone, during puberty. These hormones transform the fine vellus hair into thicker, coarser pubic hair, establishing its characteristic short cycle and frequent shedding.
Factors Causing Excessive Hair Loss
While regular shedding is normal, a sudden or excessive loss of pubic hair can signal an underlying medical issue. Hormonal imbalances are a common trigger, particularly conditions that disrupt androgen levels. A decrease in the adrenal androgen dehydroepiandrosterone (DHEA) due to an adrenal disorder can lead to thinning or loss of pubic hair.
Thyroid dysfunction, whether it is an overactive (hyperthyroidism) or underactive (hypothyroidism) gland, can also interrupt the hair cycle and cause noticeable shedding. In women, rapid hormonal shifts, such as those following childbirth or during the transition to menopause, can push a large number of hairs into the shedding phase simultaneously.
Certain nutritional deficiencies, notably low iron stores, can also contribute to hair loss across the body, including the pubic region. This occurs by disrupting the follicle’s ability to sustain the Anagen phase.
Major physical or emotional stress can induce a temporary condition called Telogen Effluvium. A significant stressor causes a sudden shift of many hair follicles into the resting phase, with shedding occurring about two to four months after the stressful event.
Less commonly, excessive hair loss can be caused by autoimmune disorders, such as Alopecia Areata, where the immune system mistakenly attacks the hair follicles. External factors like aggressive grooming practices or constant friction from clothing can damage hair shafts, leading to breakage and apparent thinning in the area.