Pubic hair, like all hair on the human body, will eventually turn gray or white. This process, known scientifically as canities, is a normal part of the aging process for hair follicles. The timing and rate of this change, however, are highly variable and subject to a complex interplay of internal and external factors. Understanding the differences in hair type and growth cycles explains why this change may not occur at the same time or rate as the hair on your head.
The Science Behind Pigment Loss
Hair color originates from specialized pigment-producing cells called melanocytes, which reside in the hair follicle bulb. These cells generate melanin, the natural pigment incorporated into the hair shaft as it grows. Hair color is determined by the mixture of two melanin types: eumelanin (black and brown hues) and pheomelanin (red and yellow hues).
The process of graying begins when melanocytes slow down melanin production and eventually die off. This loss of function is linked to the depletion or dysfunction of melanocyte stem cells, which are needed to replenish pigment-producing cells for each new hair growth cycle. Once a follicle stops delivering pigment, the hair that grows is colorless. This transparent hair, when combined with remaining colored hairs, appears gray or silver. Oxidative stress, which is cellular damage from free radicals, is also implicated as a driver that disrupts melanocyte survival and function.
Why Pubic Hair Graying Differs From Scalp Hair
The primary reason pubic hair often grays on a different timeline than scalp hair is due to a significant difference in the hair growth cycle. All hair follicles cycle through three main phases: anagen (growth), catagen (transition), and telogen (rest and shedding). Scalp hairs have a long anagen phase, lasting anywhere from two to seven years, which allows the hair to grow long.
Pubic hair has a markedly shorter anagen phase, typically lasting only a few weeks to several months. This abbreviated growth period means that pubic hair follicles cycle more frequently than scalp hair follicles. The repeated cycling exhausts the pigment-producing melanocytes more rapidly, leading to a loss of color at a different pace than the scalp.
Pubic hair is also a secondary sexual characteristic, meaning its growth and pigmentation are regulated by circulating hormones, specifically androgens. The hormonal sensitivity of these follicles plays a role in their overall health and pigmentation regulation throughout life. Hair follicles across different body regions possess their own intrinsic “melanogenic clock” that governs when they begin to lose pigment. Because of these unique regional characteristics, the graying process occurs independently, often resulting in a mosaic of hair colors across the body.
Genetics and Other Influencers of Timing
The single biggest predictor of when you will start to see gray hair, including pubic hair, is your genetic inheritance. The age at which your parents or close relatives began to gray is often a strong indicator of your own timeline. Genes regulate the point at which the melanocyte stem cell pool becomes exhausted, causing pigment production to cease.
While genetics sets the baseline, several non-genetic factors can influence the timing and accelerate the onset of graying. Chronic psychological stress, for instance, can trigger the release of stress hormones that deplete the stem cells responsible for generating pigment. Specific nutritional deficiencies can also play a role, with low levels of nutrients like Vitamin B12, copper, and zinc being linked to a premature loss of hair color. Certain medical conditions, such as thyroid disorders or vitiligo, and lifestyle factors like smoking and exposure to oxidative stress, are known to influence the rate at which pigment loss occurs.