The Effects of Shaving on Hair Growth
Does shaving cause hair to grow faster, coarser and darker? This age old
question is still asked repeatedly. A quick anatomy lesson on the structure of
the follicle should help.
The hair follicle and its hair are fundamentally one structure. This structure
can be divided anatomically into three segments:
(1) Infundibulum - the upper, funnel-shaped indentation that extends from the
polar orifice in the epidermis (the little hole where we aim our needle) to the
entrance of the sebaceous gland.
(2) Isthmus - the short midsection of the follicle, bounded by the sebaceous
gland duct and the arrector pilli muscle.
(3) Inferior - extending from the arrector muscle to the base of the follicle.
The expanded lower end of the follicle is the hair bulb, which encloses the
oval-shaped vascular-connective tissue papilla. This is an upgrowth of the
dermis containing the blood supply and nerve endings to nourish the follicle.
An anatomic change occurs at the isthmus. The entire follicle beneath the
isthmus can be considered "temporary" because it disappears during the
involutional stage, or stage of regression of the hair follicle, and reforms
again during the growth cycle. The upper segments, isthmus and infundibular,
are "permanent." At the isthmus, the cells of the inner root sheet disintegrate,
and the outer root sheath - which is no longer in contact with an inner root
sheath - begins to cornify, and form the hair we aim to remove. The hair shaft
(that is the hair that is cut off when shaving) is a dead, cornified structure
that extends from the follicle above the surface of the skin: only the follicle
is alive. To make any difference in hair growth, the follicle itself must be
disturbed. Shaving or cutting the dead structure (hair) will not have any effect
on the follicle itself.
Shaving hair really is a form of cutting hair. Like cutting with scissors,
shaving has no effect on hair growth. The myth was exploded by Dr. Mildred
Trotter at the Washington University School of Medicine. Under Dr. Trotteršs
observation, three girls shaved their legs from knee to ankle, twice a week for
a period of eight months. At the end of this time, microscopic examination
revealed that there was absolutely no increase in the diameter or color of the
hairs before or after the shaving period.
Reasons for the Misbelief After shaving there is an illusion of growth, which
has given rise to the false impression that shaving really does affect the
growth. Let us examine those points that appear to support the idea.
1. The shortness of the shaft of a shaved hair allows changes in its length to
be noticed more easily. If a hair is shaved right to the skin and then allowed
to grow 1/16 of an inch, we readily notice the difference. However if the hair
was already 6" long and it grew an extra 1/16 of an inch (in the same period as
the shaved hair) no one would be able to tell without some accurate way of
Taking the example of the male with a full beard, it is impossible to detect the
daily increase in beard growth. But it is a different story with the
clean-shaven person and his "five ošclock shadow," whose bristle growth can be
seen on the very same day.
Because the follicles of terminal hair are not at right angles to the skin,
shaving exposes more actual area of hair to the eye. If scissors are used to
clip a hair, the cut is usually at a right angle to the direction of the growth.
But shaving (given the angle of hair to blade) leaves a long-angled cut at the
end of each remaining hair fiber. When the hairs grow out from the skin, they
keep their "thickened" appearance, especially as they are being compared with
the white background of the skin.
2. Apparent coarseness is caused by the short, shaved hairs being held more
erect by the follicles clasped firmly around them.
Hairs do vary in structure, length, rate of growth, and response to various
stimuli. But the follicle must be stimulated to cause an increase in hair
growth. Shaving every day, even with vigor, would not affect the deep growing
follicle. The increased hair growth you notice after shaving is in all
probability caused by an increased hormonal stimulation. Which would have
happened, shaving or not.
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