The Lifecycle of a Hair Follicle

Hairs appear in drains and on shoulders, on combs and in brushes, on bathroom counters and shower floors. They’re stray hairs, and the sight of them can prompt people to worry that they’re losing their hair for good, sending them to contort themselves in the mirror to spot the telltale skin of a beginning bald patch and start researching hair restoration treatments. San Francisco Bay Area surgeons Dr. David Lieberman and Dr. Sachin Parikh specialize in hair restoration—but they also work to educate men and women about how hair works. In many cases, it’s just time for a hair to fall out.

Did you know it’s not uncommon to lose 50 hairs a day? Not only that but some people shed 100 hairs (or even more) every 24 hours.

Hair turnover is natural and represents the end of a hairs’ life cycle. Our job as hair restoration surgeons is to educate our patients about how hair works as well as look for the root cause of each patients hair loss.

Every person has approximately 5 million hair follicles on their body with about 100,000 of them on their head. All 5 million follicles go through its own four-stage life cycle before it falls. This is why all of your hair doesn’t usually fall out at the exact same time.

Exogen phase is the beginning of the cycle which is marked by both an ending and a beginning. An old hair falls out, pushed from the follicle by a new hair beginning to grow. The new hair signaled by the shedding of the old then enters the longest phase of its lifetime.

The anagen phase is next which is when active growth begins. At any given time, about 85 percent of the hairs will be in the angen phase.  As the hair grows over the course of years. The typical length of this phase is two to six or even eight years, during which a single hair can grow roughly six inches a year.

As a growing hair approaches the end of its life, it enters the catagen phase, a transition period that lasts one or two weeks. During this time, the hair’s follicle shrinks in size as it readies itself to eject the old hair, which separates from its source of blood and moves upward.

Finally comes the telogen phase, when the follicle rests for a few months as the disconnected hair sits in place. As the follicle regains energy to begin new hair growth, it ultimately pushes the hair out. Exogen is achieved once again, and the cycle continues.

This exogen-prompted shedding is responsible for many of the stray hairs found around the house.

People should note that a mass resting phase can be triggered by a sudden shock or stress, whether viral, physical, or even emotional. Everything from an expected event (such as childbirth) to an unexpected event (such as an accident) to an internal problem (such as an infection or diet change) can be a contributing factor. Known as telogen effluvium, this event can impact up to 70 percent of all of a person’s hair, leading to a mass fall-out—sometimes weeks or even months after the catalyst itself.

Typically, this development is not a permanent one, as follicles will return to a more normal cycle and begin producing new hairs over six to eight months.

While knowledge of a hair’s life cycle can help to ease worries about hair loss, some people still find comfort in seeking the help of a professional who specializes in diagnosing and treating hair loss. A range of other factors—from illnesses to hormone imbalances—can also cause hair loss, so it’s important to visit a doctor if there is any cause for concern that the shedding could be due to something serious.

To learn more about hair loss and the options, if necessary, for hair restoration, San Francisco Bay Area facial plastic surgeons Dr. David Lieberman and Dr. Sachin Parikh can help. Contact the Lieberman & Parikh Center for Hair Restoration by calling (650) 327-3232 or sending us a quick email.