It is a common observation that pubic hair seems to return quickly after removal, leading many to wonder if it grows at a faster pace than the hair on the scalp. This question touches on the fundamental biology of hair, which is far from uniform across the body. The apparent difference in speed and length is not about a faster growth rate in millimeters per day, but rather about the distinct programming of the hair follicle itself. Hair growth is a cyclical process that varies significantly depending on its location on the body, which explains why hair on the head can grow long while other body hair reaches a fixed, shorter length.
The Mechanics of Hair Growth Speed
The growth of every hair follicle follows a specific, repeating pattern called the hair growth cycle. This cycle is divided into three primary phases that determine the ultimate length and lifespan of the hair strand. The anagen phase is the period of active growth where cells in the hair root divide rapidly to form the hair shaft. The duration of this active anagen phase is the sole determinant of how long a hair can potentially grow.
Following this is the catagen phase, a short transitional stage where the hair follicle shrinks and detaches from the blood supply. Finally, the telogen phase is a resting period lasting several months, during which the hair remains anchored in the follicle until it is shed. The speed at which a hair is produced is similar across the body, but the length of time spent in the anagen phase creates the dramatic differences in hair length.
Comparing Pubic Hair Growth to Scalp Hair
Contrary to the common belief that pubic hair grows faster, the active growth rate of scalp hair is typically faster, growing about 0.35 to 0.45 millimeters per day. Pubic hair tends to grow at a slower rate, but the major distinction lies in the genetically determined duration of the anagen phase.
Scalp hair has an exceptionally long anagen phase that can last anywhere from two to seven years, which allows it to reach significant lengths. In contrast, pubic hair has a dramatically shorter anagen phase, typically lasting only a few months, which limits its maximum length. This shorter active growth period means that pubic hair follicles cycle much faster than scalp follicles, entering the resting and shedding phases more frequently. This rapid cycling creates the perception that it grows back unusually fast after being trimmed or removed.
Hormonal and Genetic Controls
The differences in hair growth cycles are primarily dictated by genetics and the sensitivity of hair follicles to hormones, specifically androgens. Androgens are a group of hormones, like testosterone, that act as the main regulator for many hair follicles on the body. At the onset of puberty, an increase in androgens triggers the transformation of fine, light vellus hair into the thicker, darker terminal hair seen in the pubic region.
The hair follicles in the pubic area are highly sensitive to these androgens, which is why they respond with the development of terminal hair. While androgens stimulate the growth of hair on the body, they also paradoxically signal a shorter anagen phase in these androgen-sensitive areas, establishing the fixed, shorter growth cycle. Genetic factors determine both an individual’s androgen levels and the varying sensitivity of the hair follicles, controlling the length and density of body hair.
Does Shaving Affect How Fast Hair Grows?
The perception that pubic hair grows back faster is often reinforced by shaving, but shaving does not affect the biological rate of hair growth. Shaving only removes the hair shaft at the surface of the skin and has no impact on the hair follicle beneath, which controls the growth cycle. Therefore, the rate at which the hair grows, the duration of the anagen phase, and the hair’s color or thickness are completely unaffected by a razor.
The illusion that shaved hair returns thicker, darker, or faster is due to several visual and tactile effects. When a razor cuts the hair, it creates a blunt tip, which feels coarser and stubblier as it emerges from the skin, contrasting with the naturally tapered end of an uncut hair. The newly emerging hair has not been exposed to the sun or chemicals, making it appear darker and more noticeable. This combination of a blunt, dark stubble gives the impression of rapid, dense regrowth, but it is purely a superficial effect.