Shedding: Understanding the Hair Growth Process

If you want to know why your hair sheds, you must first understand the hair growth process.

Hair grows in a cycle that consists of three phases: Anagen, Catagen and Telogen

Anagen - This is the growth phase that lasts between two and eight years. During the anagen phase the growth cells in the papilla rapidly divide and produce the hair shaft which becomes keratinized as it pushes up and out of the hair follicle into the pore. At the same time, the hair follicle grows down into the deeper levels of the dermis (skin) to get nourishment.

Catagen - The Anagen phase is followed by a brief two to four week Catagen phase or transitional phase. This is part of a renewal process where the hair follicle is literally degraded and the hair stops growing but does not fall out. During the Catagen phase the hair follicle shrinks to about 1/6 of the normal length. The lower part is destroyed, the dermal papilla breaks away, the bulb detaches from the blood supply and the hair shaft eventually is pushed up as the hair follicle disintegrates.

Telogen - The hair follicle then goes into the Telogen or resting phase for two to four months, during this time the hair still does not grow but remains attached to the hair follicle while the dermal papilla is in a resting phase below. Approximately 10-15 percent of all hairs are in this phase at any one time.

After the Telogen phase the cycle is complete and the hair goes back into the Anagen phase. It is at this time when the new hair shaft is forming that the old hair is pushed out and lost. So when you start using a product like Rogaine or Propecia you stimulate the hair follicle to start producing hair. What often happens is that many hair follicles that are in the Telogen phase then go into the growth phase.

When the hair follicle starts growing a new hair it has to first get rid of the old hair, which is still attached to the hair follicle. When this happens to many hair follicles at the same time you see a lot of hair falling out which is what causes shedding. So instead of these hairs falling out gradually at different times, they all fall out together giving you the impression that you are losing more hair.

The reality is that this hair had stopped growing and was due to fall out anyway. So shedding is a positive sign and means that you are responding well to treatment. In fact its ironic that people who respond the best to treatments often lose the most hair in the beginning. This often leads to people going off their treatment program when they should stay on it.

Shedding should last no longer than 4-6 weeks and usually occurs about 6 weeks into a hair loss treatment program. If you are still shedding a lot of hair after 2 months you should consult with your physician, as it may not be a shed. Shedding can also reoccur periodically since hairs that were put into the growth cycle at the same time have a synchronized growth cycle so they tend to go into the resting phase at the same time. This tapers off after a while. However be aware that its normal to lose between 50-100 hairs every day due to this natural growth process.